Doi:10.1016/j.clae.2004.02.007

Contact Lens & Anterior Eye 27 (2004) 87–107 Abstracts of the 28th BCLA Annual Clinical Conference, Monovision: is binocularity worth the bother or should
The effects of ageing on accommodation function
we let dominance dominate?
Department of Vision Science, Glasgow Caledonian Univer- 56–62 Newington Causeway, London SE1 6DS, UK sity, Cowcaddens Road, Glasgow G4 OBA, UK Monovision usually works well: studies suggest a success Various features of the accommodation mechanism change rate of about 50–70%. Yet, recent studies show that good with ageing and most of them seem to conspire to reduce binocularity confers a greater advantage on an individual accommodation activity. It is well established that the elas- than had previously been believed. Since monovision essen- ticity of the lens capsule declines throughout life whilst the tially sacrifices good binocularity, these two findings seem lens’ capacity to be deformed increases with ageing. These to be paradoxical. This lecture will address this apparent two factors are major causes of presbyopia. Meanwhile, cil- paradox since its resolution may help us to understand why iary muscle power does not decline with ageing and may some patients adapt well to monovision and others do not.
in fact increase. However, morphological changes in the ar- The common advice when prescribing monovision is to give rangement of the ciliary muscle in relation to the lens equa- the distance vision lens to the dominant eye. Yet, research tor and the zonule may mean that the ciliary muscle loses on ocular dominance reveals that the eye which appears to its effectiveness in accommodation with ageing even though be dominant depends on the method of testing. There are its strength remains vigorous. In this presentation, these as- three main types of ocular dominance: sighting, sensory, pects of the processes of presbyopia will be reviewed and and motor. There are several different tests within each of some consideration given to their effects on accommodation these categories, all of which may give conflicting results in function and the needs of clear near vision.
a given patient. Research on which test of ocular dominanceis most relevant when prescribing monovision will be dis-cussed. Monovision, like most healthcare interventions, is Seven years experience with silicone-hydrogels
associated with some adverse effects. Practitioners must be aware of these, not least because of possible medico-legalimplications. The main adverse effects of monovision can be Brennan Consultants, 110 Auburn Road, Auburn Village summarised as monocular blur and impaired stereopsis, and a third possibility is the decompensation of a pre-existingbinocular vision anomaly. The monocular blur can be ap- Purpose: To consider clinical experience with usage of parent at night as glare or haloes and occasionally may silicone-hydrogel materials over 7 years, and discuss con- cause difficulties during daytime vision, for example, if the temporary issues such as radical refraction changes, new distance eye’s view is obscured. Patients with monovision only very rarely report impaired stereopsis as a symptom, Method: We have been using silicone-hydrogel materials possibly because monocular clues to depth perception take for some 7 years and have continuing patients in various over from binocular stereopsis. Cases of decompensation wearing schedules including daily wear and 30-day extended of binocular vision after monovision seem to be extremely wear mode. This paper will highlight the clinical signs and rare, but it is suggested that patients should undergo a care- symptoms from these patients, analyse problems with prod- ful assessment of binocular function before monovision is ucts and look at emerging trends in the field.
Results: Ongoing patients report high satisfaction rates with the convenience and comfort of silicone-hydrogels.
Many patients enjoy the benefits extended wear offers and, Abstracts of selected papers and posters presented at the British having been warned of the potential complications of the Contact Lens Association’s Clinical Conference, Birmingham, UK, 21–23May 2004.
modality, choose flexible wearing patterns. The absence of 1367-0484/$ – see front matter 2004 Published by Elsevier Ltd on behalf of British Contact Lens Association.
doi:10.1016/j.clae.2004.02.007 Abstracts / Contact Lens & Anterior Eye 27 (2004) 87–107 ocular changes and signs such as microcysts, limbal injec- Contact lens complications in the 21st century
tion and endothelial irregularity in ongoing patients is an outstanding feature with these lenses. The more significantproblems confronting the practitioner include the incidence UMIST, P.O. Box 88, Manchester M60 1QD, UK of papillary conjunctivitis, management of corneal infiltra- Over the past 30–40 years, there has been an immense tive events and hyperopic refractive shifts in higher powered amount of scientific literature describing changes that occur lenses where the lens modulus is high. New materials and in the ocular structures during contact lens wear. As we enter designs in the silicone-hydrogel realm, such as uncoated ma- the new millennium—with a host of new and sophisticated terials for daily wear and toric lenses, demonstrate excellent lens designs and materials, lens wearing modalities and care systems, and access to exciting new ways of examining the Conclusions: With careful patient selection and instruc- cornea—we need to radically rethink our understanding of tion, continuous wear of silicone hydrogels provides a con- contact lens complications. Many complications are becom- venient, comfortable and long-lasting refractive solution for ing more important, and others are becoming less relevant.
many patients. Continued practitioner education and vigi- Now that the pathophysiological basis of most complica- lance is necessary to ensure the further success and devel- tions is well understood, more efficacious strategies can be employed to deal with those complications that do requireactive management. Although many of these changes are Progressive power lenses
asymptomatic, they can still pose a threat to ocular health and visual integrity. It is now possible in almost every caseto avoid serious complications by making careful initial ob- Wood House, Stockcroft Road, Balcombe RH17 6LH, servations and taking appropriate action. The scientific and clinical basis for this 21st century approach to contact com-plications will be outlined, and specific examples will be The form of surface which will connect spherical distance (DP) and near portion (NP) curves to provide a progressivesurface can be derived from the Davis–Fernald formula forthe variation in tangential power of a surface. The resulting Oxygen revisited: is there a better way than Dk?
surface astigmatism can be eliminated along the meridian line by varying the sagittal curvature during CNC machin-ing of the surface. It is, essentially, the sagittal curves in UMIST, P.O. Box 88, Manchester M60 1QD, UK the progression which differentiates the various makes of This lecture presents an overview of respiration on the hu- progressive lenses. In order to obtain wide aberration-free man body and considers the special case of the cornea. The distance and near zones, the blending of the DP and NP history of the development of criteria for determining the surfaces must take place only in the progression zone. This critical oxygen availability to the cornea to sustain normal produces rapid changes in power and astigmatism between corneal respiration is reviewed, and the notion that lens oxy- the zones and results in a hard design. Allowing the change gen transmissibility evaluation is the best methodology is in power and astigmatism to take place more slowly over challenged in favour of a consideration of corneal oxygen a larger area of the lens results in narrower aberration-free zones that have proved more acceptable to wearers. Such de-signs have been described as soft and generally have longer What happens to keratocytes during continuous contact
progression zones than surfaces of hard design. Adaptation lens wear?
to progressive lenses takes place in the visual cortex and themechanism is by no means properly understood. However, practice clearly indicates that in the early stages of presby- UMIST, P.O. Box 88, Manchester M60 1QD, UK opia, when the addition is low, multifocal lens wearers adapteasily to progressive lens correction as much to bifocal cor- Keratocytes play a key role in maintaining the structure and rection. As the addition increases, the advantage of having transparency of the cornea as they are the source of stromal a correction for all distances outweighs any optical draw- collagen and proteoglycans. Thus, clinicians would be con- backs of progressive lenses. A recent addition to the range cerned if any form of disease or clinical intervention threat- available is the occupational progressive lens designed for ened the integrity of keratocytes. The relatively recent de- the correction of intermediate and near vision. The change velopment of the corneal confocal microscope has provided in power between the near and intermediate zones is of- researchers and clinicians with the opportunity of observ- ten referred to as the degression power and is less than the ing the living human cornea at up to 680× magnification full addition between distance and near. This feature, and (bearing in mind that the maximum possible magnification a long progression zone, provides a wide aberration-free with a slit lamp biomicroscope is 40×). Keratocytes can be clearly observed, and researchers have begun to examine the Abstracts / Contact Lens & Anterior Eye 27 (2004) 87–107 effects of contact lens wear on keratocyte populations using power is required, these lenses may not give the desired vi- this instrument. A furious controversy has quickly emerged, whereby the research community is divided as to whether The many visual limitations that arise with hydrogel lens contact lens wear causes a reduction in the keratocyte popu- wear are overcome with GP lenses, especially when using al- lation. A possible confounding factor in this research is the ternating designs. Alternating designs vary in size and shape, role of lens-induced oedema creating an optical artefact that but they all aim to provide good alternating single vision gives the false impression of keratocyte loss. This lecture far and near. However, some of the currently available lens will briefly review the current literature and will describe a systems partially function as a simultaneous system as well.
series of confocal microscopy experiments that have sought The reading add is usually unlimited, which gives the best to clarify the question of keratocyte loss associated with outcome in people with high reading demands.
contact lens wear. It is demonstrated that contact lens wear Combinations of the above systems are often possible and does indeed cause a loss of keratocytes, and that this phe- desirable, leading to a high success rate of bifocal GP lens nomenon is unrelated to lens-induced hypoxia or oedema.
fitting in practices that are willing to invest in this technol- Etiological factors may include physical irritation of the ep- ithelium causing a release of cytokines resulting in kera-tocyte death and retardation of epithelial desquamation. A Corneal topography—a necessity in fitting contact lenses
possible clinical correlate of lens-induced keratocyte loss is stromal thinning as seen in long-term extended contact lenswear.
Geuzenkade 76, 2nd Floor, NL-1056 KP Amsterdam, TheNetherlands The art of GP bifocal contact lens fitting
Corneal topography has proven to be useful in everyday practice. It is also essential for new developments in the eyecare field such as orthokeratology and refractive surgery.
Geuzenkade 76, 2nd Floor, NL-1056 KP Amsterdam, The In this presentation, the sense and non-sense of the use of corneal topography will be covered, with special attention As an alternative to glasses, several presbyopic correction on the many new developments in this field.
options are available to our patients. Of all the options avail- To define the shape of the cornea, simple spheres and able, GP lenses offer the best optical outcome. Refractive ellipses are not sufficient. Complex mathematical formulas surgery and hydrogel contact lens wear have not been able are needed, such as Zernike polynomials, to describe that to provide the same level of visual satisfaction.
shape, which can be done with a fairly high level of accuracy There are numerous lens designs available within the GP presbyopic lens group, which may appear challenging and However, one should bear in mind that the cornea remains confusing to practitioners. However, fitting presbyopic pa- human tissue, which can be altered and influenced in many tients with GP lenses is less difficult than it appears. Despite ways. Age, but, for instance, accommodation as well, seems the fact that there are numerous systems available, they can to influence the topography of the corneal surface. In ad- all be categorised into a limited number of basic designs.
dition, modern corneal topographers have their limitations If single vision lenses (under- or overcorrection or monovi- when reproducing the shape of the cornea. Different types sion) are not the preferred solution, there are only two main of corneal topographers are available today and their limi- presbyopic options left: simultaneous vision and alternating What information is clinically relevant when fitting con- The amount of time spent behind a computer and other tact lenses? A good estimation of the corneal astigmatism work/leisure-related activities, corneal shape as assessed by and whether this is located centrally or peripherally, for in- topography, degree and shape of astigmatism, degree of ec- stance is. Based on the information about corneal shape, centricity, previous lens wear, lens fit, comfort of wear, hy- lenses can be fit that respect the shape of the cornea bet- poxia, contrast sensitivity, pupil size, eyelid shape, fissure ter, which can increase comfort of wear. Currently, several size, blink rate, lens movement, tear film characteristics, an- new lens designs are available serving to achieve this goal.
terior chamber depth, depth perception, and the prescription Bi-aspheric lenses (two meridians with different eccentric- itself all play a part in the choice and in the success of this ity) for instance serve to respect the shape of the cornea bet- ter in low and peripheral corneal astigmatism. Furthermore: Different simultaneous designs are available, all offering quadrant specific lenses are commercially available now to a true multifocal system making it suitable for patients with serve the special needs of the cornea better. But this is only intermediate distance demands, especially those doing com- the beginning: custom made lenses based on cornea topog- puter work. Among many others, optical quality and the in- raphy will change the future of GP lens fitting.
fluence of the lens on the corneal surface are the main rea- Optical performance is one of the major advantages of GP sons for choosing one design over the other. If high near lens wear, but improvement is always welcome, and may Abstracts / Contact Lens & Anterior Eye 27 (2004) 87–107 be desirable. The possibilities and limitations of wavefront cessing steps may have an effect on the resultant lens—from corrected GP lenses will be discussed.
its clinical performance (e.g. lens centration and movement)to its physical and chemical characteristics (e.g. lens surface Getting back to vision
wettability and mechanical properties).
The decision as to which technology should be used to manufacture a particular lens is based on factors such as Vision CRC and Cornea & Contact Lens Research Unit, wear modality, clinical use, ease of manufacture (material UNSW, Level 5, Rupert Myers Building, Gate 14, Barker and design) and commercial considerations. However, key Street, Kensington 2033, NSW, Australia factors which are affected by different manufacturing tech-nologies such as surface chemistry and bulk material phys- Breakthroughs in optical measurements and manufacturing ical properties have not been directly compared. Further- technology has made possible contact lenses which could more, the clinical benefits of these manufacturing processes correct more than just sphere and cylinders. We are now see- ing aberration-corrected/controlled designed contact lenses Notwithstanding a considerable body of scientific ev- becoming available. So, how far could we go with this tech- idence that has defined the clinical performance and physico-chemical properties of soft lenses, there has been To attempt to answer this question, we will review the little attempt to establish a relationship between these two research outcome from around the world in the area of aber- fundamental descriptors of contact lens performance as they relate to the different methods of lens manufacture.
This lecture will provide an overview of the history and The future is near: up-coming treatments for presbyopia
development of soft contact lens materials and manufacture and restoring accommodation
with particular emphasis on the different processing steps involved and how these steps might affect the final lens. Ex-perimental results investigating the impact of manufacturing Vision CRC and Cornea & Contact Lens Research Unit, processes on various characteristics of soft lenses will be UNSW, Level 5, Rupert Myers Building, Gate 14, Barker presented together with how these are related to their clini- Street, Kensington 2033, NSW, Australia This presentation details the current developments aimed at Mechanisms of accommodation and presbyopia
restoring accommodation to the presbyope. The predicted performance, benefits (and drawbacks) of strategies rangingfrom pseudo-accommodation devices to phaco-ersatz tech- College of Optometry, 4901 Calhoun Road, Houston, TX Surgical procedures are increasingly being employed to pro- (I) Disadvantages associated with convention presbyopia vide optical compensation for presbyopia. These include corneal refractive surgery and the use of bifocal, diffractive or multifocal intraocular lenses. In addition to these more (a) Pseudo-accommodating and accommodating de- traditional surgical interventions a number of controver- sial experimental surgical procedures have become available (b) Phaco-ersatz and related surgical approaches.
which are said to reverse the effects of presbyopia throughthe restoration of accommodation. These so-called scleralexpansion procedures include radial ciliary sclerotomy and Soft contact lens materials and manufacture
surgical implantation of scleral expansion bands. The the- oretical basis for these surgical procedures flies in the faceof current understanding of the accommodative mechanism Department of Optometry & Neuroscience, UMIST, P.O. Box and the causes of presbyopia and inadequate clinical testing of these patients leaves considerable doubt as the efficacy Hydrogel materials are highly sensitive to the processing or possible beneficial consequences of these highly experi- and fabrication conditions to which they are subjected. This mental surgical procedures. An overview of the anatomy of is likely, therefore, to be a relevant consideration in the the accommodative apparatus of the eye will be presented.
production of hydrogel (‘soft’) lenses since these lenses The classical Helmholtz accommodative mechanism will be are currently manufactured by different methods. The most detailed with videographic evidence from ongoing studies widely used methods are lathe-cutting, spin-casting and cast- on rhesus monkeys. This will be followed by a overview of moulding. Lenses made by these different methods of man- factors contributing to the development of presbyopia that ufacture will undergo very different material processing— are supported by experimental evidence from studies of hu- particularly polymerisation. These different material pro- man eye-bank eyes and non-human primates. This includes Abstracts / Contact Lens & Anterior Eye 27 (2004) 87–107 evidence for lenticular factors such as hardening or sclero- Grading of corneal transparency in contact lens practice
sis of the lens as well as extralenticular factors such as loss Clare O’Donnella,b,∗, James Wolffsohna,b of choroidal elasticity with increasing age. The relevance ofthe scientific data addressing the causes of presbyopia will be put into the context of approaches aimed at restoring ac- bAston University, Birmingham B4 7ET, UK commodation in presbyopes. The scleral expansion surgi- Purpose: To examine the academic literature regarding cal procedures will be described and the theoretical basis corneal transparency grading and to assess the potential use of scleral expansion surgery to restore accommodation will of objective image analysis in clinical contact lens practice.
be presented and critiqued in light of experimental evidence Method: Reference databases of academic literature against them. The future prospects of surgical interventions were searched and relevant articles reviewed. Annunziato, aimed at restoring accommodation will be considered with Efron (Millennium Edition) and Vistakon-Synoptik corneal reference to ongoing experimental work on the surgical rein- oedema grading scale images were analysed for relative in- troduction of accommodative intraocular lenses.
tensity, edges detected, variation in intensity and maximumintensity. The recovery from corneal oedema (induced us- Optical and cortical mechanisms for simultaneous vision
ing a thick hydrogel contact lens worn for 3 h on a patched multifocals
closed eye) was monitored by image analysis of the corneal optic section and compared to ultrasound pachymetry, visualacuity measures and objective bulbar hyperaemia grading.
R&D Optics Center, Bausch & Lomb, 1400 North Goodman Results: Many attempts to measure corneal transparency Street, P.O. Box 30450, Rochester, NY 14603-0450, USA have been described in the academic literature, mainlyto investigate the effects of refractive surgery. Assess- Simultaneous vision multifocals are unique among oph- ment of grading scale images identified that the change thalmic presbyopic corrections in that their optical effects are between grades was best described by quadratic paramet- present for all gaze positions. However, because of their op- ric or sigmoid three-parameter functions. Scales depict- tical structure, their performance is generally more suscep- ing corneal light scatter over the pupil (Annunziato and tible to variation in pupil size. Lens designers have put con- Vistakon-Synoptik) were best correlated to average intensity.
siderable emphasis on minimising (e.g. “pupil independent”, However, corneal optic section images (Efron scale) were Echelon) or exploiting (e.g. “pupil intelligent”, Acuvue) this most strongly correlated to variations in intensity across the relationship. Nevertheless, these design strategies produce a optic section. The significant increase in corneal thickness retinal image for all viewing distances that is only partially in induced in the oedematous eye (14.3%, P < 0.001) and its focus. Numerous researchers have documented the resulting subsequent recovery was most strongly correlated with the contrast reduction and, in certain cases, secondary images intensity variation across the corneal section, accounting (“ghosting”). Recent advances in technology for measuring and analysing monochromatic aberrations of the human eye Conclusions: Corneal oedema is best determined by the have permitted us to better understand how simultaneous intensity variation across the width of a corneal section.
vision lenses work or fail to work. These analyses show Corneal oedema induced by soft contact lens wear is not that the “add effects” for most of these designs are directly easily determined over the pupil area by sclerotic scatter related to the amount of spherical aberration present in the eye/lens combination. Conversely, the overall quality ofvision is inversely related to this combination. Aberrations Surgical management of presbyopia
generally associated with decentred optics (e.g. coma) tendto be higher with simultaneous vision lenses than with single vision lenses. It is also useful to compare the visual perfor- mance of simultaneous vision lenses to that of another oph-thalmic strategy possessing benefits of gaze independence, The holy grail for refractive surgeons is the management monovision. Simultaneous vision provides better perfor- of presbyopia. A multitude of techniques have been tried to mance than monovision in many functions requiring binoc- surgically manage this problem and this talk is an overview ular inputs (e.g. fusional ranges, stereopsis). Conversely, of what is available and the results that can be achieved.
interocular suppression of blur requires a well-focused Corneal treatments include presbyopic ablation profiles with image in one eye, a condition that is best achieved with the excimer laser. Scleral techniques include scleral expan- monovision. Nevertheless, there is evidence that patients sion bands and ‘reading implants’. With reading implants, in can learn to interpret and cope with degraded images. Their data submitted for the European CE mark for this product, willingness to accept these compromises is strongly influ- approximately 96% of patients were able to read J2 uncor- enced by habitual vision demands and to a smaller degree rected post-operatively without correction with a follow-up by certain psychological characteristics. This information of up to 4 years. The British experience is very similar al- is useful in presbyopic patient and method selection.
though follow-up as yet is relatively short. Intraocular tech- Abstracts / Contact Lens & Anterior Eye 27 (2004) 87–107 niques include multifocal implants and the new accommo- Purpose: With the introduction of silicone hydrogels there dating lenses. The authors experience is that the newest ac- has been increasing interest in reducing the equilibrium wa- commodating implants give about 2–2.5 D of accommoda- ter content to enhance oxygen permeability through the con- tion. All available techniques, at present, reduce the depen- tact lens. However, it has been proposed that the aqueous dence on glasses for close work and do not remove the need phase plays an important role in ensuring on eye movement during overnight wear. This study describes the results froma range of laboratory research methods, which can be applied Factors that influence patient choice in laser refractive
to assess the necessary properties of the aqueous phase.
surgery or contact lenses
Methods: Rotational mobility of water and solutes is mea- sured using electron spin resonance and proton and sodium Shehzad A. Naroo∗, Navneet Gupta, Gurpreet S. Bains nuclear magnetic resonance. Translational ion mobility is Neurosciences Research Institute, Aston University, Birm- assessed using impedance spectroscopy, which can also be employed to monitor aqueous phase continuity by dielectrictechniques.
Purpose: To explore patient’s motivations in choosing re- Results: Both rotational and translational mobility within fractive surgery or contact lenses and what factors influence hydrogels is increasingly restricted with reduction in water content. When compared with bulk solution there is typi- Methods: A one-page questionnaire was presented to con- cally a 100× reduction in mobility of ions and water in 38% secutively presenting patients at four refractive surgery clin- HEMA. Ion mobility is severely restricted when further low- ics (one low prices high street laser clinic, one long es- tablished laser clinic, one large optical company with an Conclusions: The results indicate that a balance between in-house laser facility and one consultant ophthalmologist) the polymer and aqueous phases is imperative to ensure oxy- and three contact lenses practices (one specialist CL prac- gen and ion/water co-continuous phases. On eye movement tice, one large optical company and one low price optical may be influenced to a greater extent by hydraulic relax- ation than ion mobility across the contact lens. By using a Results: Overall, amongst the refractive surgery patients group of research tools as outlined, it provides results that (n = 212) there was a prevalence of female patients, mean can predict whether it is viable to advance a polymer to the age for all clinics was 39.2 ± 10.6 years. Amongst the con- next stage of development and expensive clinical trials.
tact lens patients (n = 115) there was a prevalence of femalepatients (similar to previous studies), mean age for all clinics The death of GP lenses is highly exaggerated
was 30.8 ± 12.4 years. The main reason for choosing refrac-tive surgery or contact lenses seemed to be cosmetic reasons, work related and sports. Reasons for not choosing contact 1820 Algaroba Street, Honolulu, HI 96826, USA lenses were inconvenience (79%), dry eyes (20%) and over-wear (22%). Reputation of the clinic was the most common It is the year 2004 and the GP lens is alive and well. The reason (58%) for selecting a refractive surgery practice. The contact lens field has made a change that has set the stage authors also disseminate the results to look at differences for the 21st century. Continuous vision is a reality. Hyper amongst the four refractive surgery clinics and the three con- Dk/t silicone hydrogels for up to 30 days, hyper Dk/t GP lenses for up to 30 days, corneal refractive therapy (CRT), Conclusions: Primary motivations for refractive surgery intra-limbal lenses, semi-scleral lenses are now all available.
seemed to be cosmetic reasons since few patients cited con- The physiological breakthroughs of hyper Dk/t materials tact lens complications that could not be managed. Contact will be thoroughly discussed especially in relation to the lens clinicians may be able to hold onto patients and not GP situation. The scientific data and physiological benefits lose them to refractive surgery with better management. The of hyper Dk/t will be thoroughly discussed, including the opinions of clinicians involved in primary eye care seemed to latest results on corneal ulcer incidence for CW GP lens use be very influential in helping patients decide on their method will be discussed. A thorough discussion of how to integrate of refractive correction, which is encouraging as past studies hyper Dk/t GP lenses into your practice from daily wear to have not shown this. Patients should be encouraged to seek continuous wear, from spherical to custom lenses will be advice from ophthalmic clinicians and clinicians should re- The era of continuous wear, GP hyper Dk contact lenses
Understanding the role of the aqueous phase in soft con-
tact hydrogels
1820 Algaroba Street, Honolulu, HI 96826,USA David Austin∗, Brian P. Hills, Les Sutcliffe, Francis Tailoka The contact lens field has made a change that has set the APU, East Road, Cambridge CB1 1PT, UK stage for the 21st century. Continuous vision is a reality.
Abstracts / Contact Lens & Anterior Eye 27 (2004) 87–107 Hyper Dk/t silicone hydrogels for up to 30 days, hyper Dk/t GP lenses for up to 30 days, and corneal refractive ther- apy (CRT) are now all available. The physiological break- (G) Ulcer incidence with both modalities: throughs of hyper Dk/t materials will be thoroughly dis- (1) Thirty-six cases reported world-wide so far with cussed. What does hyper Dk/t really mean and how is it dif- ferent than lenses of the past? The scientific data and physi- (2) No reported cases of ulcer with GP lenses.
ological benefits of hyper Dk/t will be thoroughly explained including corneal epithelial changes and, in particular, Pseu- domonas adhesion to epithelial cells and risks of corneal ul- ceration. The second hour will cover the clinical differences between GP and silicone hydrogel CW with an emphasis (H) Results of a clinical comparative study between on GP 30-day CW, including trouble shooting with both Night&Day versus Menicon Z for 30-day CW (UMIST, • To review the meaning of Dk and Dk/t in relation to clin- Scleral lenses for keratoconus and transplants: analysis
of visual outcome
To understand the physiological differences with hyperDk/t contact lens materials.
• To understand the physical properties of hyper Dk/t ma- Moorfields Eye Hospital, City Road, London EC1V 2PD, To review relative risks of corneal infection by lens trans-missibility.
Purpose: This presentation reviews the current management • To understand the FDA results from the CW studies and of keratoconus or other primary corneal ectasia (PCE) and to make correlations to clinical practice.
corneal transplant, with scleral contact lenses (ScCLs), the • To introduce possible problems with hyper Dk/t materials.
cases assessed from a dedicated ScCL Clinic at Moorfields • To understand how to resolve such problems.
Eye Hospital. The visual acuities for both groups are com- • To compare and contrast the soft and GP CW.
pared, and the relative visual performance of the fellow eyenoted.
(A) Dk values, transmissibility categories: Methods: The principal underlying contact lens indication, (1) Oxygen permeability, Dk and its measurement.
and the visual acuities for a group of patients with PCE or corneal transplant was recorded between September 1999 (3) Benjamin oxygen transmissibility classifications.
(B) Physiological benefits of hyper Dk/t: Results: Eight hundred and five patients (1308 eyes; 1070 (1) Confocal microscope studies on corneal epithe- PCE, 238 transplants), a mix of new referrals and existing ScCL wearers, were seen in the 52-month period. At the (2) Increased Pseudomonas aeruginosa adherence to time of writing, 429 (686 eyes) continued with lens wear, the epithelium with lower Dk/t lens materials.
PCE 559 eyes, transplant 127 eyes, the remainder either (3) Clinical studies concerning P. aeruginosa adher- discontinued wear, did not proceed at the time of the trial, were in progress pending a first after-care appointment or (4) Discussion of risk of corneal ulcer with different lost to follow-up. In the PCE group, 83 eyes achieved 6/6 or better, 305 eyes achieved 6/9 to 6/12, 114 eyes achieved 6/18 (5) FDA post-approval of 30-day CW lenses to verify to 6/24 and 41 eyes achieved below 6/24. The transplants achieving the same acuities were 58, 76 and 7, with 3 at (C) Polymer chemistry and lens materials: less than 6/24. The ScCL wearing eye in unilateral PCE cases was better in 9 cases, and worse than the fellow eye in 47. The respective figures for unilateral transplants was the reverse pattern, with 34 and 9 cases, respectively.
Conclusion: ScCLs provide a feasible alternative to corneal lenses in the management of PCE and corneal transplant. The expected visual acuity for transplants fitted (D) Results of the FDA study for Menicon Z.
with ScCLs is approximately two Snellen lines better than for PCE. In unilateral transplant cases, the ScCL wearing eye generally had a better acuity than the fellow eye, but for PCE requiring just one ScCL, the fellow eye more often Abstracts / Contact Lens & Anterior Eye 27 (2004) 87–107 Orthoptic indications for contact lens wear
widths were obtained from the spectra with the fitting pro-grams EWVOIGT and LOWFIT.BAT. 23Na NMR studies were undertaken on a temperature controlled Bruker MSL Institute of Optometry, 56–62 Newington Causeway, London 300 spectrometer operating at 79.387 MHz for sodium. By applying the CPMG pulse sequence spin–spin relaxation T2values were obtained for both silicone and conventional hy- Orthoptic anomalies are prevalent: they are encountered in at least 5% of patients seen in a typical primary eye care prac- Results: Curve fitting analysis of the two techniques pro- tice. Many orthoptic anomalies are best treated with con- vides evidence for a range of mobility within each of the hy- tact lenses, and recent developments in contact lens practice drogels under investigation. ESR results display spin corre- make this approach increasingly feasible. Several cases are lation times from 10−6 to 5 × 10−11 s for 38% EWC HEMA reviewed that highlight the role of contact lenses in treat- and 0.154 mol saline, respectively, whereas 23Na T2 relax- ing orthoptic anomalies. Amblyopia affects about 3% of the ation is reduced by a factor of 60. Inter-relating these two population, and anisometropic amblyopia may be the most techniques shows that the environment to a similar extent common form of amblyopia [Attebo et al., 1998]. Winn et al.
affects both probes since both have volumes in solution of (1988) showed that contact lens correction of anisometropia maintains the aniseikonia at a minimum level in axial as well Conclusions: The mobility of the ESR probe and sodium as refractive anisometropia. So, from an optical point of view ion reduces as a function of water content. Results indicate contact lenses are the preferred method of correcting ani- both techniques provide evidence for up to three different sometropia, and it is often argued that anisometropia should sites of mobility, which may either indicate different states be corrected as young as possible to most effectively treat of water or different volume fractions of the aqueous phase amblyopia. However, fitting contact lenses to patients, par- ticularly children, with anisometropic amblyopia has beenproblematic because there is no immediate binocular acu-ity improvement when the contact lenses are inserted which Transverse ion mobility in hydrogels by impedance spec-
reduces patient motivation. Extended wear with silicone hy- troscopy
drogels represents a breakthrough for these cases. A series David Austin∗, Francis Tailoka, Vasant Kumar of anisometropic patients, mostly children, who have beencorrected in this way are presented. In addition to improve- APU, East Road, Cambridge CB1 1PT, UK ments in the best corrected acuity of the amblyopic eye, some Purpose: The extensive patent literature outlines the nec- cases show good stereoacuity with contact lenses in patients essary properties of silicone hydrogels to maintain on-eye who could not obtain this with spectacles. Other cases are movement. It has been proposed that the water content is described where contact lenses were used to correct accom- critical to ensure sufficient ionic and hydraulic permeability.
modative esotropia and, in an unusual case, an actor with This study outlines a method to measure ion mobility and high myopia, astigmatism, and decompensating esophoria aqueous pathway continuity and compare the results with was corrected with soft toric contact lenses incorporating two prism diopters base out each eye. It is concluded that Methods: Data was obtained using a Solartron 1260 there are orthoptic anomalies where contact lenses are the impedance analyser supported by Z Plot software. Sample preferred mode of correction. It is in patients’ best interest hydration was maintained by constructing a custom de- for practitioners to recommend contact lenses in these cases.
signed cell permitting controlled sample/electrode contactpressure. By varying the molar concentration of the aqueous Utilisation of spin probes to investigate the aqueous phase
phase within the hydrogel, it is possible to measure both in soft contact lens hydrogels
ion mobility and dielectric properties.
David Austin∗, Les Sutcliffe, Brian P. Hills Results: In high water content hydrogels, ion and oxy- gen mobility are equally obstructed by the polymer network, APU, East Road, Cambridge CB11PT, UK however, in hydrogels with water contents lower than 38% Utilisation of spin probes to investigate the aqueous phase EWC, there is a very sharp drop in ion mobility. Conductivity of amidose saline was 2 Sm−1, 38% HEMA and PureVision Purpose: This study aims to investigate the aqueous phase 0.02 Sm−1, and Night&Day 1.42 × 10−5 Sm−1. An impor- by electron spin resonance and 23Na nuclear magnetic reso- tant outcome of this study is that CIBA Vision Night&Day nance. By monitoring the rotational mobility of a spin probe had a ion mobility in the same order of magnitude as a con- and sodium ions in different hydrogels, it is proposed that ventional HEMA/MMA hydrogel with EWC of 26%.
this will provide a useful insight into the internal dimensions Conclusion: The low ion mobility exhibited by the CIBA and micro viscosities of the aqueous phase in hydrogels.
Vision Night&Day material suggests that ion transport Method: For the ESR technique, samples were hydrated through the material plays a less significant role to ensure with an aqueous solution of the NaTMIOS spin probe. Line on-eye movement. Careful dielectric analysis can determine Abstracts / Contact Lens & Anterior Eye 27 (2004) 87–107 if the aqueous phase is a series of continuous or blocked lial cell appearance in a prospective, single centre, masked, Methods: Fourteen silicone hydrogel CLs wearers using Concentration of water soluble gentamicin in aqueous,
lenses on an extended wear basis (mean experience 5 ± 1 delivered by corneal collagen shields
years), 23 wearers using hydrogel CLs on an long-termextended wear basis (mean experience 13 ± 4 years) and Sanjay Mantry∗, Vijay Hegde, G.T. Smith, Rosemary Robin- 18 non-lens-wearing age-matched controls were recruited.
Epithelial thickness at the central cornea and at four pe- Coventry and Warwick Hospital, Stoney Stanton Road, ripheral locations was measured using a modified optical pachymeter. Cell regularity and intensity of light backscat-tered from the basal epithelium were assessed using a slit Purpose: This was a pilot prospective non-randomised con- trol, single centre trial to evaluate the efficacy and safety Results: There were significant differences in epithelial of corneal collagen shield as a mode of antibiotic delivery thickness between all subject groups (ANOVA, P < 0.001; after cataract operation. The objective of this study was to post-hoc testing P < 0.005). Hydrogel wearers had the see whether minimal inhibitory concentration (MIC) of gen- thinnest central corneal epithelium (46 ± 10 mm), followed tamicin is achieved in the aqueous humour when soaked in by silicone hydrogel wearers (54 ±14 mm) and non-wearing controls (58 ± 9 mm). Topographical position did not affect Methods: Ten subjects were recruited from patients who epithelial thickness. Epithelial thinning was not associated are due to have routine cataract surgery from day surgery unit with the duration of wear. Hydrogel CL wear was associ- at Coventry and Warwick Hospital. In addition to the nor- ated with reduced basal epithelial cell regularity, however, mal pre-operative regime of dilating the pupil with topical no reduction was demonstrated in silicone hydrogel CL use.
drops, a self-dissolving collagen shield soaked in gentamicin The transparency of the basal cell layer was unaffected by (40 mg/ml for 30 min) was placed on the eye. Exposure time will for variable intervals before surgery (minimum time: Conclusions: Long-term wear of silicone hydrogel CLs is 30 min; maximum time: 180 min) to allow different lengths associated with epithelial thinning but to a lesser degree than of time for the antibiotic to soak through the cornea into observed with hydrogel CLs. Morphological alterations to the anterior chamber and so determine the length of time the basal epithelial cell layer are observable in long-term hy- required to reach a therapeutic dose of the antibiotic where drogel wearers. A cumulative effect of the duration of wear it is needed. The contact lens was taken off the eye in the on the changes observed could not be demonstrated, which operating theatre, just before starting the actual procedure.
may offer some reassurance for wearers with prolonged ex- A tiny sample of fluid (0.2 ml of aqueous) was taken from the eye through the normal cataract wound at the start of theoperation and sent to the laboratory to be analysed for theamount of antibiotic. The exclusion criteria included pre- Preliminary results of the comparison of multiple sur-
vious eye surgery, only good eye, ocular surface problems, vey instruments for patient satisfaction with overnight
associated ocular co morbidity (glaucoma, retinal disease, orthokeratology study
Marjorie Rah∗, Melissa D. Bailey, John Hayes, Alan Kwok Results: The collagen shield which was very comfortable mode of delivery from patients of view. The concentration of New England College of Optometry, 1255 Boylston Street, antibiotics at various times will be discussed and the results were encouraging which has prompted a further prospective Purpose: To compare symptoms and satisfaction before and after corneal refractive therapy (CRT). Secondarily, to assesschange in corneal thickness with CRT.
Effects of long-term lens wear on the corneal epithelium
Methods: Forty CRT patients were enrolled at the New Fiona Stapleton∗, Isabelle Jalbert, Deborah Sweeney England College of Optometry. Visual acuity, refrac-tion, corneal topography, symptoms and satisfaction (NEI CCLRU, School of Optometry and Vision Science and Vi- RQL-42), central corneal thickness and corneal epithelial sion CRC, University of New South Wales, Sydney 2052, thickness were measured at baseline, 1 day, 1 week, 1, 3, 6 months and 1 year. Three-month data are reported.
Purpose: Corneal epithelial thinning follows short-term wear Results: Of the 40 CRT patients, 9 discontinued prior of silicone hydrogel contact lenses (CLs). After 12 months to completion of the study. Mean subscale scores for of wear, there is partial recovery of epithelial thinning, how- the NEI RQL-42 at the 32-month visit were: clarity of ever, the long-term effects of wear are unknown. The aim of vision = 69.3; expectations = 51.1; near vision = 90.0; this study was to measure the effects of long-term wear of far vision = 88.2; diurnal fluctuations = 74.0; activity these CLs on the epithelial thickness profile and basal epithe- limitations = 96.5; glare = 62.4; symptoms = 82.4; depen- Abstracts / Contact Lens & Anterior Eye 27 (2004) 87–107 dence on correction = 84.5; satisfaction with correction = of wear. Preliminary results from the in vitro experiments 75.5. Higher scores indicate better quality of life. There demonstrated that continued cycling was associated with were no statistically significant differences in symptoms uptake of PHMB, Aldox, Tetronic 1304 and 1107 into the when compared to a sample of LASIK patients at the Ohio State University at the 1- or 3-month visits after ad- Conclusions: Preliminary data indicate that subjects who justing the comparisons for baseline differences between wear group II hydrogel or group I silicone-hydrogel lenses groups. Full corneal thickness measurement showed that soaked in a PHMB-based system on a daily wear basis, may changes in the central cornea were statistically signifi- exhibit clinically meaningful corneal staining during the first cant at 1 week (P = 0.008). There was a general trend few hours after insertion without the associated subjective towards central thinning and peripheral thickening. Data collected for epithelial thickness did not show significantchanges.
Dynamic wetting behaviour of pHEMA–MAA and sili-
Conclusions: The lack of differences in symptoms and cone hydrogel contact lenses
satisfaction between CRT and LASIK patients following Ralph Stone∗, Howard Ketelson, David Meadows, Nat Mc- treatment are attributed either to a lack of sensitivity of the instrument (NEI RQL-42) to detect differences, or that nodifference between these two groups exists in terms of qual- Alcon Laboratories Inc., 6201 South Freeway, Fort Worth, ity of life. Changes in total corneal thickness were consis- tent with previously reported studies; however, the epithelial Purpose: Utilise a new technique to measure dynamic con- thickness changes are not, perhaps due to limitations of the tact angle as an indicator of contact lens wettability for hy- Methods: A sessile water drop technique was used in Corneal response of chemical agents released by hydro-
conjunction with high speed video equipment to measure gel and silicone-hydrogel lenses as a function of time
advancing dynamic contact angles for unworn and patient Ralph Stone∗, Renee J. Garofalo, Nissanke Dassanayake, worn contact lenses. The curved profile of the lens surface was analysed using a fitting algorithm to calculate the con-tact angles. The lenses were cycled through buffered saline Alcon Research Ltd., Fort Worth, TX, USA and air exposures to simulate exaggerated blinking condi- Purpose: The adsorption and release of chemical agents tions. Measurements were made in the presence of various found in commercially available multi-purpose solutions non-ionic surfactants and disinfection products.
(MPS) were evaluated to determine the effect on corneal Results: The contact angles of the pHEMA–MAA lenses increased from approximately 20–100◦ after 9–10 cycles Methods: A series of pilot research studies were con- and they were independent of the lens water content. The ducted as a 2-week, prospective clinical trial, using a double- change from the hydrophilic to hydrophobic lens surface masked, randomised, crossover design. Adapted asymp- could not be reversed when the dewetted lens was repeat- tomatic lens wearers wore hydrogel or silicone-hydrogel edly soaked in buffered saline solution. For silicone hydro- contact lenses for a maximum period of time each day. New gel lens, the initial contact angles were higher than those lenses were dispensed for each wear period. Prior to wear, observed for the pHEMA–MAA lens. Dewetting kinetics lenses were pre-soaked in Alcon-OPTI-FREE-Express- were much slower in the case of the silicone hydrogel lens.
MPDS, B&L-ReNu MultiPlus-MPS, CIBA Vision-SOLO- The influence of surfactant pre-treatment on the wettabil- care-PLUS MPS, or AMO-Complete-MoisturePLUS-MPS ity of the pHEMA–MAA lens showed Tetronic-1304 gave for 12 h overnight. Subjects rated comfort and ocular symp- excellent wettability. Comparatively, the lens pre-soaked toms. The ocular surface was examined at baseline and after in Tetronic-1107 solution showed rapid dewetting fol- lens removal with fluorescein. The cornea was evaluated lowing the early cycling stages, indicating low retention according to its type (grades 0–4) and area (0–100%). The of the Tetronic-1107. These same trends were observed uptake of chemical agents from new, unworn control lenses for commercial disinfection products containing these was determined in vitro by UV spectroscopy.
Results: Clinically significant levels of relatively asymp- Conclusions: The pHEMA–MAA lenses showed signif- tomatic corneal staining were observed at 1 and/or 2 h when icant dewetting properties when the lenses were cycled subjects wore the group I and II lenses soaked in the PHMB- through saline solution–air. The dewetting effects of the sil- based systems. The PHMB systems showed greater inci- icone hydrogel lenses were significantly different compared dents of staining than the POLYQUAD group. All signs to the pHEMA–MAA lens. There was a strong lens wetting were reduced or not measurable after 6–8 h. When subjects dependency on the type of surfactant used in the pre-soaking used the POLYQUAD-based solution with lens groups I, II solution and subsequent substantivity of the surfactant. The and IV, only minimal staining was observed at 1 and 2 h different surface chemistries of the pHEMA–MAA and Abstracts / Contact Lens & Anterior Eye 27 (2004) 87–107 silicone hydrogel lenses appeared to play a key role in the rigid gas permeable (RGP) scleral contact lens for visual Results: In total, 193 scleral contact lenses were used: (a) Wearer demographics in the US post-approval evalua-
60% (115) were used in moderate/advanced keratoconics, tion of lotrafilcon A
post-keratoplasty astigmatism to improve visual acuity; (b)23.32% were used as cosmetic scleral lenses for traumatic purposes, pthisical eyes and for decompensated cornea; and Clinical Trial Consultant, 2097 East Lake Road, Atlanta, (c) 17% (33) eyes had innovative sclerals mainly in kera- tonics intolerant to other varieties of contact lenses.
Conclusions: Scleral contact lenses continue to have a Purpose: To profile the patient demographics among pa- very wide application. In the vast majority of cases reviewed tients prescribed 30 night continuous wear in the post-market in this busy tertiary centre, scleral lenses formed an essential surveillance study for lotrafilcon A lenses in the US.
form of visual and non-visual correction.
Methods: Baseline demographics were self-reported by the 6245 enrolled wearers. The distribution of gender and Clinical performance and corneal staining associated
refractive status was compared to concurrent contact lens with silicone-hydrogel materials used on a daily-wear
wearer databases. The distribution of age and years of lens Results: Males comprised 36% of the wearers in the Kathy Dumbleton∗, Lyndon Jones, Simone Bayer, Desmond post-approval evaluation compared to 32% of the referent database (P < 0.01, Chi-square test). The median lens Centre for Contact Lens Research, University of Waterloo, power was −3.00 D, yet there were twice as many pa- tients with refractive error above −6.00 D (1145 wearers or18.3%) in the lotrafilcon group compared with data from Purpose: The purpose of this study was to determine the other types of lenses (9.1%, P < 0.05, Chi-square test). Of clinical performance of one polyhexanide (PHMB)-based the enrolled cohort; 14.8% or 924 wearers were aged 50 system (ReNu MultiPLUS) and one peroxide (PX)-based years or older and 33.8 were age 40 years or older. Eight system (AOSept), when used to disinfect PureVision (PV) hundred (12.8%) of the wearers in this cohort reported more and Focus Night&Day (FND) silicone hydrogel (SH) lenses, than 20 years of lens wearing experience.
Conclusions: Continuous wear lotrafilcon A lenses have Methods: A 2-month prospective clinical trial was con- been prescribed to many types of patients, including a sub- ducted on 20 myopic soft lens-wearing subjects who were stantial proportion of middle-aged patients, a large propor- symptomatic of dryness with their contact lenses. Subjects tion of patients with high refractive errors and long years of were refitted with a contralateral pair of PV and FND lenses, wearing experience. The advantage of high oxygen trans- which were worn on a DW basis. Subjects were randomly missibility will be beneficial to a wide variety of contact assigned ReNu or AOSept for two consecutive 1-month pe- riods, using a cross-over design. After each month, a newpair of lenses was dispensed. Subjects were examined at Review of indications of scleral contact lenses in tertiary
hospital
Results: Subjectively, the lenses and care regimens be- haved similarly, with no significant differences in levels of Sanjay Mantry∗, Waheeda Illahi, K.A. Jones, Jackie Lamb, comfort, dryness, vision or stinging on insertion for any of the combinations (P = NS). Lens comfort reduced (P <0.001) and dryness increased (P < 0.001) over the day of Optometry Department, Birmingham & Midland Eye Centre, wear, regardless of the lens/care regimen combination (P = Dudley Road, Birmingham B18 7QU, UK NS). PX-disinfected lenses showed no statistically signifi- Purpose: For decades, scleral contact lenses have been fitted cant differences in corneal staining from baseline with either in the hospital eye services for therapeutic purposes. The lens type (P = NS). ReNu produced significantly greater application of scleral lens use, is widely known. The purpose corneal staining at both follow-up visits than at baseline of this study was to analyse the indications of using scleral (P < 0.001), with more staining observed with the PV lenses contact lenses in a tertiary referral centre.
than the FND lenses (P < 0.001). Unacceptable staining oc- Methods: A retrospective analysis of the scleral contact curred in 47% of the ReNu-PV eyes and 21% of the ReNu- lens database at the Optometry Department of the Birming- FND eyes. The severity of the staining was generally mild ham & Midland Eye Centre over the past 2 years was done.
(<25 on a 0–100 scale) and demonstrated a pattern in which The scleral contact lenses were divided into three subgroups: peripheral staining was greater than that observed centrally.
(1) polymethyl methacrylate (PMMA)-sighted lenses for vi- Conclusions: These results indicate that certain care reg- sual purposes; (2) PMMA-cosmetic scleral contact; and (3) imens used with SH materials have a potential to produce Abstracts / Contact Lens & Anterior Eye 27 (2004) 87–107 different patterns of corneal staining than that observed with pre-presbyopes wearing progressive contact lenses, despite HEMA-based materials and that the staining obtained is rel- atively asymptomatic. Lens care regimens must be carefullyevaluated for their clinical performance with SH materials Impact of previous extended and daily wear schedules
and practitioners must be aware that not all care systems on signs and symptoms with high Dk lotrafilcon a lenses
Robin Chalmers∗, Sally Dillehay, Bill Long, Joseph Barr, Do progressive contact lenses negate ocular accommo-
Peter Bergenske, Peter Donshik, Glenda Secor, John dation in pre-presbyopes—implications for myopia con-
2097 East Lake Road, Atlanta, GA 30307, USA Olivia Hunt∗, James Wolffsohn, Carlos Garc´ıa-Resúa, Purpose: The purpose of this study was to determine the impact of previous lens wearing schedule on the signs and Neurosciences Research Institute, Aston University, Birm- Methods: In a multi-centre clinical trial 140 subjects with Purpose: Several recent studies have suggested that it may previous daily wear (DW) and 140 with previous extended be possible to retard the progression of myopia in children wear (EW) were enrolled and re-fit with lotrafilcon A with progressive spectacles. The rationale for their use is that (Night&Day) lenses to use on an up to 30 night continuous positive power at near reduces accommodative effort (per- wear basis. Their ocular signs and symptoms were tracked haps increasing accommodative accuracy) and consequently reduces the stimulus for growth of the posterior vitreous seg- Results: Nearly 85% of the subjects completed the year.
ment. A logical next step would be to consider progressive Signs of limbal and conjunctival redness and neovasculari- contact lenses. Theoretically, these should cause the young sation were significantly improved by the 1-week visit. Pap- patient to accommodate less at near than with single vision illary changes improved in the former EW group only. No contact lenses and this is examined in this study.
significant change was noted in conjunctival or corneal flu- Methods: Twenty subjects (12 female, 8 male, average orescein staining. A significantly larger proportion of the age 21.40 ± 3.07 years) with a range of mean spherical re- DW subjects presented at baseline with frequent or moder- fractive error (−5.50 to +3.50 D) viewed in random order, ate to severe symptoms compared to previous EW subjects.
high contrast static targets (Maltese cross) at 0.1, 0.5, 1.0, Severity and frequency of dryness during the day and the 2.0 and 3.0 D accommodative demand matched for angu- severity of end of day dryness were reduced significantly by lar subtense in free space. The measurements were made the 1-week visit in the former DW subjects. Frequency of with subjects fully corrected (in random order) by each of the end of day dryness was significantly decreased by the Acuvue daily disposable (SVCL), Ultravision Igel multifo- 1-week visit and continued to resolve over the first 6 months cal (PACL) and Acuvue bifocal (BICL) contact lenses. Ac- of the study. The severity of end of day dryness diminished commodation was monitored objectively with the open view sharply during the first week of lotrafilcon usage.
IR Shin Nippon SRW-5000. Both PACL and BICL had a Conclusions: Previous DW and EW showed slightly dif- near addition of +2.50 D. Three indexes of accommodative ferent time course in the resolution of the physiological accuracy were used: response level for a 3 D stimulus, ac- changes that had developed from their previous lens wear.
commodative slopes and error indexes derived from accom- Previous DW subjects presented at baseline with greater symptoms compared with users of EW. Most subjects ex- Results: When corrected by SVCL, the accommodative perienced relief of their symptoms within the first week of response at 3.0 D demand was 2.21 ± 0.52 D and the slope and error index of the stimulus response curve 0.95 ± 0.16and 0.79 ± 0.46, respectively. However, with progressive Clinical and biochemical changes with silicone-hydrogel
contact lenses, the response were significantly lower (BICL: contact lenses
response 1.73 ± 0.56 D (P = 0.0003), slope 0.82 ± 0.18 Jacinto Santodomingo-Rubido∗, Aisling Mann, James (P = 0.009); PACL: response 1.83 ± 0.58 D (P = 0.02), Wolffsohn, Valerie Franklin, Brian Tighe, Bernard Gilmartin slope 0.82 ± 0.11 (P = 0.001)).
Conclusions: The results suggest that patients accommo- Neurosciences Research Institute and Biomaterials Research date less with PACL and BICL than with SVCL. If reducing Unit, Aston University, Birmingham B4 7ET, UK accommodative effort is able to retard the development of Purpose: Despite a careful and regular cleaning regime, sur- myopia, contact lenses may be more successful than specta- face deposits adsorbed on silicone-hydrogel (SiH) contact cles as the near addition remains in the line of sight with eye lenses may induce inmmunological and/or pathological re- movement and they are less likely to be removed by chil- actions leading to adverse events such as contact lens pap- dren. However, significant accommodation is still exerted by illary conjunctivitis and contact lens peripheral ulcers. This Abstracts / Contact Lens & Anterior Eye 27 (2004) 87–107 study reports the clinical and biochemical ocular changes ing day the patient consulted an optometrist local to her experienced by neophyte SiH wearers monitored over an home with increased lacrimation, redness and pain and was immediately referred. She was diagnosed to have micro- Methods: Forty-seven subjects were fitted with SiH lenses bial keratitis and corneal scrapping isolated Pseudomonas and randomly allocated one of the two materials currently on aeruginosa. Aggressive treatment was immediate (ofloxacin the market (balafilcon A or lotrafilcon A) on either daily or hourly, gentamicin hourly) and included hospitalisation.
continuous wear basis. New techniques for objective grad- Examination 1-month post-event included logMAR visual ing (i.e. red extraction) of bulbar and palpebral hyperaemia acuity, videokeratoscopy, videoaberroscopy, slit lamp pho- were employed together with tear meniscus height and sub- tography, confocal microscopy. It revealed permanent VA jective measurement of non-invasive tear break-up time be- loss, increased corneal aberrations, multiple deep corneal fore and 1, 3, 6, 12 and 18 months after initial fitting. The scarring within the pupillary area and endothelial cell loss.
amount of protein extracted from worn lenses was measured The poster will describe in details this case history that using a combination of immunoassays and electrophoretic confirms that despite full respect of the cornea oxygen phys- iological needs, silicone hydrogel can produce mechanical Results: After 18 months of SiH contact lens wear, a sig- corneal damage that facilitates bacterial penetration and nificant increase in bulbar and palpebral hyperaemia was infection. The case highlights the need for rapid and cor- observed in all contact lens groups (P < 0.05). SiH lenses rect diagnosis and the very grave consequences of delay in did not induce significant changes in tear meniscus height and non-invasive break-up time (P > 0.05). A significantincrease in the positive incidence of specific protein markers Detection of keratoconus by videokeratoscopy (BCLA
Dallos Award)
Conclusions: Significant changes in clinical signs were observed in neophyte SiH wearers and were associated withthe positive incidence of specific protein markers. None of 42 Vauxhall Bridge Road, London SW1V 2RX, UK the proteins investigated could be regarded as being specific Purpose: Clinicians habitually describe the distortions asso- to one particular disease or adverse response, although the ciated with keratoconus as irregular astigmatism. In fact, the findings presented would suggest that their assessment may distortions are the manifestations of increased level, com- prove useful in the quantification of distinct events in con- pared to normal, of higher-order aberrations. Several work- tact lens wear. The detection of protein markers in the ocu- ers have suggested the use of videokeratoscopes to detect lar environment together with clinical monitoring of ocular early keratoconus, and have developed proprietary algo- physiology provides extremely valuable information for the rithms. Videokeratoscopes becoming widely used in a clin- development of contact lens materials and solutions as well ical routine, it becomes important to quantify the optical as for the therapeutic use of drugs and the management of quality of the cornea with an established analytic technique.
a variety of contact lens disorders.
In the field of ocular aberrations measurements, there is nowa consensus to use Zernike polynomials to describe aberra- Case report: silicone hydrogel microbial keratitis
tions. The aim of the current study was to develop a Zernike Will Ayliffe∗, Michel Guillon, Marine Gobbe, Nita Mahal- based keratoconus detection scheme that is usable for all Methods: The study was carried out on 45 diagnosed ker- Mayday University Hospital, 530 London Road, Croydon, atoconus eyes and 28 suspected keratoconus eyes. The data obtained was compared to a reference population of 870 The case report relates to a contact lens wearing patient referred with painful, photophobic red eye to Croydon Results: Total fourth-order aberrations and coma along Eye Hospital casualty by a local optometrist. The re- y-axis (Z3-1) were the best detectors for the differentiation port describes a case of Pseudomonas aeruginosa ulcer between suspected keratoconus and normal corneas (speci- with 30-day continuous wear silicone hydrogel, highlight- ficity 81.6%, sensitivity 75.0% for fourth-order aberrations; ing contributory factors to the severity of the event that specificity 71.9%, sensitivity 89.3% for Z3-1). The total lead to vision loss and permanent scarring. The patient, fourth-order aberrations and coma along y-axis (Z3-1) were a 26-year-old female, had successfully worn Easy Vision also the most efficient detectors for diagnosed keratoconus All Day All Night contact lenses for 3 years, changing her (specificity 93.3%, sensitivity 94.2% for fourth-order aber- contact lenses monthly, and wearing them without removal rations; specificity 88.9%, sensitivity 94.1% for Z3-1).
on average of 30 days. She presented to her contact lens Conclusions: The results demonstrated an improved use practitioner at midday complaining of pain, itchiness, red- of videokeratoscope as a diagnostic tool for keratoconus ness, light sensitivity. After examination, she was instructed detection that can be used for all types of videokerato- not to wear contact lenses and was sent home. The follow- Abstracts / Contact Lens & Anterior Eye 27 (2004) 87–107 The relationship between corneal thickness, corneal to-
Methods: Disinfection susceptibility of five P. aeruginosa pography and ocular surface temperature, as measured
isolates (three invasive, two cytotoxic) was investigated us- by infrared thermography
ing laboratory-soiled contact lenses, unsoiled (new) lensesand disinfectant only controls. The FDA/ISO organic soil Christine Purslow∗, Jacinto Santodomingo-Rubido, Carlos model was utilised. Four disinfectants were assessed: (A) preserved with polyquaternium-1 0.001% and myristamido- Neurosciences Research Institute, Aston University, Birm- propyl dimethylamine 0.0005%; and (B–D) preserved with polyhexamethylene biguanide (PHMB) 0.0001%. An ini-tial inoculum of 5 × 105 CFU/ml was achieved, and the Purpose: The origin of the source of the thermal radiation number of bacterial survivors was determined at 4 and 6 h from the anterior eye is ambiguous. This study examines the influence of corneal thickness, corneal topography and Results: Susceptibility to solution A did not vary signifi- tear film stability on ocular surface temperature, by use of cantly between the P. aeruginosa strains with soiled or un- soiled lenses. However, resistance to solutions B–D varied Methods: Seventeen subjects (nine males, eight females; between strains, with poorer efficacy observed with soiled age 27.1 ± 3.8 years) underwent measurement of central compared to unsoiled lenses for at least one of the isolates corneal thickness (ultrasound pachymetry, Nidek UP-1000), (P < 0.05). Solution A was the only disinfectant to achieve anterior surface corneal topography, corneal thickness log reductions of at least 3.0 for all strains under all test and anterior chamber depth (Orbscan), non-invasive tear conditions. Invasive strains were more resistant than cyto- break-up time (TBUT, Tearscope) and non-contact ocular toxic strains to solutions B and D at 4 h post-inoculation surface temperature (OST, ThermoTracer TH7102MX). The dynamic ocular surface temperature profile was measured Conclusions: P. aeruginosa isolates varied in susceptibil- for 8 s continuously after a blink. Custom-designed soft- ity to PHMB preserved solutions in the presence of soiled ware allowed quantitative objective analysis of the digitised lenses, but did not vary in susceptibility to solution A. In- thermal images over the surface of the anterior eye, which vasive strains were more resistant than cytotoxic strains to could be mapped on to the corresponding corneal thickness two of the PHMB preserved solutions when associated with soiled lenses. Investigation of a wider range of invasive and Results: Central OST is strongly correlated with OST of cytotoxic isolates, and alternative soil models, will further the more peripheral conjunctiva (r = 0.94; P < 0.001). OST enhance our understanding of P. aeruginosa resistance to was unrelated to corneal thickness (ultrasound: r = −0.31, 0.23; Orbscan: r = −0.26, P = 0.33) across all regions of the cornea. OST was also unrelated to corneal topography(r = −0.38, P = 0.13) and anterior chamber depth (r = Evaluation of povidone-iodine as a disinfectant solution
−0.06, P = 0.82). The relationship between OST and tear for contact lenses: antimicrobial activity and cytotoxity
film quality approached significance (r = −0.45, P = 0.07).
for corneal epithelial cells
Conclusions: The physical properties of the cornea appear Ryoji Yanai∗, Kiichi Ueda, Motoharu Tajiri, Toru Mat- to have little influence on OST. These results support previ- sumoto, Keiji Kido, Shigeru Nakamura, Fumio Saito, Teruo ous theories that OST measured by infrared thermography is principally determined by the tear film. Hence, thermogra-phy is a useful, dynamic, non-invasive method for assessing 1-1-1 Minami-Kogushi, Ube-City, Yamaguchi 55-8505, Purpose: Povidone-iodine (PVP-I) possesses broad-spectrum Effect of organically soiled contact lenses on disinfection
antimicrobial activity and is used clinically as a disinfec- susceptibility of Pseudomonas aeruginosa strains
tant. To evaluate the disinfectant properties and safety of PVP-I for use as a contact lens solution, we compared theeffects of PVP-I with those of three chemical components Clinical Vision Research Australia, The University of Mel- of commercially available disinfectant solutions for contact lenses on microbial growth and the viability of culturedcorneal epithelial cells.
Purpose: We have shown that P. aeruginosa isolates vary in Methods: The disinfectant effects of PVP-I, hydrogen their resistance to chemical contact lens disinfectants when basic inorganic ions are made available to the bacteria dur- 2O2), polyhexamethylene biguanide (PHMB), and benzalkonium (BAK) were assessed by incubation with ing testing. Resistance appears to be linked to acute cyto- Staphylococcus aureus or Candida albicans and enumera- toxicity. The aim of this study was to investigate the effect tion of viable cells remaining after various times (30 s to of organically soiled contact lenses on disinfection suscep- 24 h) by the ISO 14729 standard method; the concentrations tibility of cytotoxic and invasive P. aeruginosa strains.
of the various agents required to reduce the number of mi- Abstracts / Contact Lens & Anterior Eye 27 (2004) 87–107 crobial cells by 3 log units during a 30 min exposure were ‘Correction’ of presbyopia with 1CU intra-ocular lenses
determined. The cytotoxicity of the four disinfectant compo- James S. Wolffsohna,b,c,∗, Olivia Hunta,b,c, Bernard nents for SV40-transformed human corneal epithelial cells Gilmartina,b,c, Shezhad Narooa,b,c, Sunil Shaha,b,c, Mark was evaluated by staining with neutral red and determina- Bensona,b,c, Ian Cunliffea,b,c, Sanjay Mantrya,b,c tion of the NR50 value for a 30 min exposure.
Results: The 3 log values (in ppm) measured with S. au- a Neurosciences Research Institute, Aston University, Birm- reus or C. albicans were 14.38 and 33.72, respectively, for Birmingham & Midland Eye Centre, Birmingham, UK for PHMB, and 14.96 and 9.74 for BAK. The NR50 values cMidlands Eye Institute, Solihull, UK (in ppm) measured with corneal epithelial cells were 160.11 Purpose: To determine the restoration of subjective and ob- for PVP-I, 165.05 for H2O2, 50.26 for PHMB, and 12.06 jective accommodation in eyes implanted with the 1CU ac- for BAK. The safety margins for S. aureus or C. albicans commodative intra-ocular lenses (IOL).
were 11.13 and 4.75, respectively, for PVP-I, 0.01 and 0.01 Methods: Twelve subjects, 20 eyes (33–78 years, aver- for H2O2, 0.54 and 0.33 for PHMB, and 0.81 and 1.24 for age 60.7 ± 15.4 years, three males, nine females), with a 1CU accommodative intra-ocular lens implanted in one or Conclusions: The results suggest that PVP-I has a greater both eyes had a full binocular refraction and both distance antimicrobial effect and a lower cytotoxicity for human and near acuity measured with a logMAR chart. Subjec- corneal epithelial cells when compared with commercially tive amplitude of accommodation was measured with the available disinfecting agents for contact lenses. PVP-I thus RAF rule. The objective accommodative stimulus–response appears to be efficient and safe for use as a contact lens curve for static (Maltese cross) targets (matched for angular subtense) was measured using the Shin Nippon SRW-5000.
Requirements for anterior eye image capture
The subjects viewed the targets monocularly, in random or-der, at 0.17, 0.50, 1.00, 1.50, 2.00, 2.50, 3.00 and 4.00 D James S. Wolffsohn∗, Rachael C. Peterson accommodative demand. Continuous objective recording of Neurosciences Research Institute, Aston University, Aston dynamic accommodation was measured with the SRW-5000 with the subject viewing a target moving from 0 to 2.50 Dat 0.3 Hz through a Badal lens system. Wavefront aberrom- Purpose: To review current technologies for anterior eye im- etry measures were made through undilated pupils using the age capture and describe a study to determine the minimum image pixel resolution and maximum compression appro- Results: The best corrected acuity was −0.01 ± priate for anterior eye image capture storage.
0.16 logMAR at distance and 0.60 ± 0.09 logMAR at near.
Methods: Images of the bulbar conjunctiva, palpebral con- Subjective amplitude of accommodation was 2.24 ± 0.42 D.
junctiva and corneal staining (fluorecein viewed with cobalt The objectively measured static amplitude of accommo- blue illumination through a Wratten filter) were taken at the dation was 0.72 ± 0.38 D, although individual responses maximum resolution of the Canon CoolPix990 (2048×1360 varied greatly. The average dynamic amplitude of accom- pixels), MP (1280 × 811 pixels), JVC KYF58 3-chip (767 × modation was 0.71 ± 0.47 D with a lag behind the target of 569 pixels) and JAI CV-S3200 single chip (767 × 569 pix- 0.50 ± 0.48 s. Aberrometry showed a decrease in power of els) digital cameras. The images were stored in TIFF format the lens-eye combination from the centre to the periphery and further copies created with reduced resolution (using in all subjects, on average −0.38 ± 0.28 D/mm.
bicubic resampling) or using compression (JPEG or BMP).
Conclusions: The objective accommodating effects of the The images were then ranked for clarity on a 15 in. cathode 1CU lens appear to be limited, although patients are able ray-tube monitor (resolution 1280×1024 pixels) by 10 prac- to track a moving target. The greater subjective amplitude titioners and analysed by objective image analysis grading of accommodation is likely to result from the eyes depth of [Contact Lens Anterior Eye 2003:26;27].
focus of and the aspheric nature of the IOL.
Results: Image quality was first perceived as reduced when the pixel resolution was lower than 767×569 pixels, regard- Clinical and subjective response to daily wear of a high
less of the camera used. This was also the case when image Dk silicone hydrogel among adapted low Dk soft contact
were saved with greater than 50% JPEG or BMP compres- lens wearers
sion. Image analysis techniques were more critical, particu-larly with edge detection, with features of interest best de- termined using medium levels of compression.
CIBA Vision Corporation, 11460 John’s Creek Parkway, GA Conclusions: It is appropriate to store anterior eye images at a 767 × 569 pixel resolution and 50% JPEG compression,resulting in storage space savings of approximately 7× and Purpose: To examine the clinical and subjective response of 70× (compared to a 2048 × 1360 pixel resolution TIFF), adapted, low oxygen permeable (Dk) daily wear (DW) soft contact lens wearers when dispensed for 1 month in a low Abstracts / Contact Lens & Anterior Eye 27 (2004) 87–107 water, high Dk lotrafilcon A silicone hydrogel soft contact following 1 week, 1 and 2 months of daily wear. Lenses Methods: Eighty-seven subjects who had at least 6-month Results: Bulbar and limbal hyperaemia decreased signif- experience wearing low Dk soft contact lenses for at least 5 icantly in all quadrants during the study. The reduction was days per week for at least 8 h per day for DW were dispensed most marked for the temporal and nasal limbal quadrants to wear lotrafilcon A lenses for DW for 1 month. Subjects (>10 units, P < 0.0001) and was most apparent between used their habitual lens care systems with the lotrafilcon the baseline and 1-week visits. Subjects reported a corre- A lenses. Follow-up visits were at 1 week and 1 month.
sponding reduction in end of day redness and dryness and Eight-one subjects completed the trial.
improved end of day comfort compared with their previous Results: Biomicroscopy signs of conjunctival redness, conjunctival staining, corneal neovascularisation, limbal Conclusion: Hyperaemia in contact lens wearers may be redness and papillary conjunctivitis showed improvements attributed to a number of factors including hypoxia. Refitting after 1-week and 1-month wearing lotrafilcon A lenses.
existing low Dk lens wearers with SH lenses on a daily wear Signs of corneal oedema, corneal infiltrates, epithelial mi- basis can result in a decrease in hyperaemia which may be crocysts and mucin balls were clear at dispensing and remained clear at each follow-up. Corneal staining aver-aged 0.1 (1–4 scale) at dispensing and all follow-up visits.
thickness
measurements
ultrasonic
Biomicroscopy signs improved for 57% of eyes at 1 week pachymetry and the Orbscan in keratoconic and normal
and for 74% of eyes at 1 month. On average, 69% of sub- subjects
jects reported symptoms of redness, dryness or irritation at Waheeda Illahia,b,∗, Neil Charmana,b baseline. At 1 week 52% and at 1 month 53% of subjectsnoted these symptoms. Forty-nine percent of subjects re- a Optometry Department, Birmingham & Midland Eye Cen- ported an improvement in the time they could comfortably Conclusions: The results from this trial indicate that clin- Purpose: The aim of this study was to compare the corneal ical improvements are seen and subjective benefits are ex- thickness measurements obtained using ultrasonic (US) perienced by adapted low Dk DW soft contact lens wearers pachymetry with the Orbscan II in keratoconic and normal who wear high Dk silicone hydrogel soft contact lenses.
Methods: Ninety-six eyes of 60 keratoconic patients who Changes in hyperaemia subsequent to refitting long-term
had varying degrees of keratoconus, underwent corneal to- low Dk lens wearers with silicone hydrogel lenses on a
pography using the Orbscan II (Bausch & Lomb Surgi- daily wear basis
cal, Rochester, NY). This was repeated on 31 normal sub- Kathryn Dumbleton∗, Nancy MacDougall, Lyndon Jones, jects. Central corneal thickness (CCT) was measured in all the normal subjects using an ultrasonic pachymeter (PAC-SCAN 300, Sonomed, Clement Clark Inc., Lake Success, Centre for Contact Lens Research, University of Waterloo, NY, USA). In the keratoconus group of patients the Orb- scan map was used to locate the apex of the cone and apical Purpose: High Dk silicone hydrogel (SH) lenses are able thickness (AT) was measured, the CCT was also measured.
to offer many physiological advantages for daily wear Results: The mean ultrasonic central thickness (UCT) in addition to the continuous wear modality for which and Orbscan central thickness (OCT) in normal sub- they were originally developed. The purpose of this study jects (mean age 31.52 ± 6.72) was 575 ± 49.41 and was to investigate the effect of refitting long-term low 606 ± 47.76 mm, respectively. With default correction OCT Dk lens wearers with SH lenses for daily wear on ocular was 557 ± 43.96 mm. The UCT and OCT in the keratoconic group (mean age 30.83 ± 8.30 years) was 509 ± 83.50 and Methods: As part of a larger cohort, successful low Dk 427 ± 57.70 mm, respectively. The default correction factor lens wearers were recruited to participate in this study. To reduced the OCT value to 396 ± 70.39 mm. In assessing date, 35 subjects (7.6 ± 2.5 years wear) have been enrolled the apical thickness in the keratoconic group using the US into the study. All subjects attended the baseline visit having pachymeter (UAT) and the Orbscan (OAT), mean values of worn lenses for at least 6 h. Bulbar and limbal hyperaemia UAT 483 ± 76.54 and 401 ± 78.49 mm were obtained.
were graded on a scale of 0–100 in each quadrant. All sub- Conclusions: In keeping with previous studies, higher jects were then refitted with Focus Night&Day SH lenses; CCT were found using the Orbscan compared with the ul- however, in order to reduce the potential for bias, they were trasonic pachymeter in normal eyes. In keratoconic eyes informed that they were being randomly assigned to either Orbscan readings were up to 82 mm lower compared with wear low Dk lenses or to wear the SH lenses and would be the US pachymeter. A statistically significant difference was unaware of lens assignment. Subjects returned for follow-up found between the two instruments. The Orbscan does not Abstracts / Contact Lens & Anterior Eye 27 (2004) 87–107 provide reliable corneal thickness readings in cases of ad- have been compared with those wearers who have not de- veloped corneal infiltrates (control) within the first 3 monthsof the study.
A 2-year retrospective study of the indications and suc-
Results: Infiltrates were confirmed in 91 wearers; 5990 cess rates of different types of therapeutic contact lenses
other wearers passed 3 months in the study without reportof infiltrates. Factors significantly associated with the events Waheeda Illahi∗, Jacqueline Lamb, Clare Maguire were age <30, <25 and <20 years (odds ratio (OR) = 1.6, Optometry Department, Birmingham & Midland Eye Centre, P = 0.029; 1.7, P = 0.008; 1.8, P = 0.016, respectively); Dudley Road, Birmingham B18 7QU, UK report of never being married (OR = 1.6, P = 0.024),wiping hands instead of washing hands before lens handling Purpose: To perform a clinical audit of the various reasons (OR = 6.3, P = 0.0002). Swimming while wearing lenses for, and types of, therapeutic contact lenses fitted in the showed a trend for association with events (OR = 1.5, P = Optometry Department of a major eye teaching hospital in 0.08). Being a new wearer to contact lenses was found to be protective (OR = 0.3, P = 0.04). Ninety-five percent Methods: A review of the case notes of 75 consecutive patients referred to the contact lens department between Conclusions: These results indicate that age under 30 November 2000 and November 2002, took place. The rea- years, report of casual hand washing behaviour and swim- son for referral, type of contact lenses fitted success of the ming while wearing lenses may be associated with the contact lens and the improvement in vision was analysed.
development of corneal infiltrates with continuous wear of Results: (a) The diagnosis at time of referral was ker- silicone hydrogel lenses. Counselling patients with these atoconus (57%), penetrating keratoplasty (13%), aphakia factors at the time of fitting about early symptoms of corneal (12%), followed by trauma requiring cosmetic contact lens inflammation may help prevent the development of these fitting (10%), intractable diplopia (3%), and others (5%). (b) The main type of contact lens design used was Kera I and II(31%), Rose K (17%) soft contact lenses, none of these were The effect of contact lens wear on ocular surface tem-
keratoconic (14.7%), Rose K post-graft (6.7%), Quasar K at perature (BCLA DaVinci Award)
9% followed by other smaller groups. (c) Fifty-six percentof the contact lenses fitted at first attempt were ‘successful’ and tolerated with little difficulty. Thirty percent required Neurosciences Research Institute, Aston University, Birm- further refits over the course of the 2 years for various rea- sons including progression of the condition in the case ofkeratoconus.
Purpose: To examine dynamic temperature changes of the Conclusions: A variety of different contact lenses have anterior eye with contact lens wear.
been fitted in this tertiary referral centre for differing condi- Methods: Forty-eight subjects (21.7 ± 1.9 years) had their tions. It is hoped that this detailed retrospective study will ocular surface temperature measured with a non-contact, in- provide useful clinical information for short- and long-term frared camera (ThermoTracer TH7102MX) following a min- management of this department and provide those interest- imum of 2 h wear, and immediately following lens removal.
ing in developing further expertise in this areas, a more ac- Subjects wore: no lenses (n = 8 control); lotrafilcon A on a curate clinical profile of likely patient types.
continuous (LCW; n = 8) or daily wear basis (LDW; n = 8);balafilcon A on a continuous (BCW; n = 8) or daily wear Baseline wearer-reported factors associated with devel-
basis (BDW; n = 8); or etafilcon A on a daily disposable opment of corneal infiltrates with silicone hydrogel lenses
regimen (EDW; n = 8). All contact lens wearers had been for continuous wear: an interim report
wearing lenses for over 1 year. The dynamic ocular surfacetemperature profile was measured for 8 s continuously after a blink. Custom-designed software allowed dynamic quanti-tative objective analysis of the computerised thermal images.
CIBA Vision Corporation, 11460 Johns Creek Parkway, Du- Results: Ocular surface temperature immediately follow- ing contact lens wear was significantly greater compared Purpose: To measure the association of baseline wearer- to non-lens wearers (35.5 ± 1.1 ◦C versus 37.8 ± 0.9 ◦C; reported factors with the development of corneal infiltrates P < 0.01), predominantly in the LCW group (38.5±2.0 ◦C; with continuous wear of lotrafilcon A lenses.
P < 0.001). However, there was no difference with modal- Methods: Wearers registered in the Focus Night&Day ity of wear (DW 37.5 ± 1.6 ◦C versus CW 37.8 ± 1.9 ◦C; post-approval evaluation completed an extensive question- P = 0.63) or material (SiH 37.6 ± 1.9 ◦C versus etafilcon naire on proposed risk factors for the development of compli- A 37.8 ± 0.7 ◦C; P = 0.79). Temperature on top of the cations from lens wear. Responses from wearers who devel- lens was highly correlated (r = 0.97) to, but lower than oped a corneal infiltrate at any time since enrolment (event) (−0.57±0.16 ◦C) that beneath the lens. Ocular surface cool- Abstracts / Contact Lens & Anterior Eye 27 (2004) 87–107 ing following a blink was not significantly affected by con- performed to evaluate the efficacy and safety of corneal re- tact lens wear (P = 0.32).
shaping with this overnight orthokeratology contact lens de- Conclusions: Ocular surface temperature is greater with sign. All the lenses were in siloxy-fluoromethacrylate Dk contact lenses in situ, regardless of lens material or modality 100 gas-permeable material (hexafocon A).
of wear, probably due to the thermal insulating properties Methods: Fifty eyes of 25 myopic patients aged from 11 to of a contact lens. Increased eye temperature has been impli- 44 years were treated. All the subjects with a mesopic pupil cated in bacterial binding, dry eyes and inflammation and diameter larger then possible BOZD where excluded. The hence this new technique offers great potential for clinical baseline refractive error was from −1.00 to −6.00 D spher- ical equivalent, WTR astigmatism up to 1.50 D and ATRor oblique astigmatism up to 0.75 D. Subjective rating, un- The development of a disposable ophthalmic barrier sys-
aided visual acuity, subjective refraction, best-corrected vi- tem to prevent cross-infection from contact ophthalmic
sual acuity, pupillometry, corneal topography, corneal wave- devices—an update
front analysis, and biomicroscopic data were collected. Vis-its included baseline, dispensing, 1 day, 1 week, 1 and Charlotte Henley∗, Valerie Franklin, Brian Tighe, Jonathan 3 months after lenses were worn. For all the subjects an overnight wear was scheduled. After overnight wear, data Biomaterials Research Unit, CEAC, Aston University, Birm- were collected in the morning immediately following lens removal and 12 h after lens removal.
Results: The cornea responds rapidly with significant It is generally accepted that there is a potential risk of cross- (P < 0.05) central corneal flattening and improvement in vi- infection from contact ophthalmic devices. Examples of sual acuity after just 60 min of lens wear; the corneal shape cross-infection include: (a) herpes simplex; (b) adenovirus; changes from prolate to oblate asphericity after one night (c) prions and theoretically CJD transmission; and (d) HIV.
of wear; in the majority of cases improvement in unaided The current methods used to prevent this cross-infection are visual acuity up to 0.1 logMAR can be obtained for at least either inefficient or not cost effective and have limited ap- 12 h after lens removal in the first week of treatment. These plications, e.g. tonometer heads and silicone sheaths. Most changes were sustained at 1 and 3 months. In the first week, commonly the contact areas of these ophthalmic devices there was a significant improvement in subjective ratings of are sterilised by wiping with an alcoholic swab, but this is quality of day and night vision (P < 0.05) but a significant inadequate and ineffective. It is proposed that the disposable increase of corneal spherical aberration (P < 0.05) due to barrier system is universal, meaning that the system can post-treatment oblate shape of the cornea. Subjective ratings be applied to several types of ophthalmic contact devices continued to improve after objective measures stabilised at including the Goldman tonometer, Gonioscope lenses and 1 week. No significant ocular adverse events were observed A-scan ultrasound probes of the eye. The properties of a suc- cessful universal disposable barrier film are: (a) disposable; Conclusions: The preliminary results of this study suggest (b) reversible adhesive layer; (c) optically transparent; (d) that the corneal epithelium is able to be moulded or redis- small mass to avoid recalibration of the ophthalmic device; tributed very rapidly in response to the tear film forces gen- (e) non-permeable barrier film; and (f) compatible barrier erated behind this reverse-geometry lens design. Safety and film with the tear film. A four-layer barrier system prototype efficacy of the procedure appear to be favourable without sig- is currently being developed and undergoing clinical trials.
nificant adverse reactions; however, future studies are needed This four-layer barrier system consists of a barrier film, to determine the more long-term outcomes of treatment.
which is coated with an adhesive hydrogel. Protective linersmaintain the adhesive layer and barrier film sterility until thedevice is used. An indication of the fabrication technology Co-management in refractive surgery
and results from initial clinical evaluation will be presented.
Refractive outcome and corneal response to a customised
Aston Academy of Life Sciences, Aston University, Birming- esa-curve reverse-geometry lens designs for overnight or-
thokeratology
Many patients will express an interest in exploring the pos- sibilities that refractive surgery can offer and will requireadvice on what it involves and its likely success rate from Via 2 Giugno 52, I-50052 Certaldo (FI), Italy them. Patients who discuss their desire to undergo refractive Purpose: We have developed and patented a new design and surgery procedures with their own optometrist often report calculation method to customise a multi-curve reverse ge- comments from their optometrist such as ‘laser surgery is ometry lens. This new design is based on a biconic model still experimental’ or ‘the results are not stable’. Usually op- on which we developed an esa-curve customised reverse ge- tometrists that dismiss refractive surgery are those who are ometry lens design. A prospective, randomised study was ill-informed about current techniques. At the very least op- Abstracts / Contact Lens & Anterior Eye 27 (2004) 87–107 tometrists should be aware of the type of surgery that is avail- tact lenses can dislodge while manoeuvring under positive able in their local vicinity and to obtain an idea of the results acceleration, form gas bubbles underneath the lens during being achieved, especially nowadays that refractive surgery low atmospheric pressure, and require a prolonged adaptive has found a firm foothold as an alternative to optical aids.
period. The most significant operational problem with soft Those with more of an interest may already be involved in a contact lenses (SCL) is intolerance. This is most likely to oc- ‘shared-care’ type co-management scheme with a local re- cur when the humidity is low and/or there is a high amount fractive surgeon or refractive surgery centre. Recognition of of particulates in the air, such as in a hot, dusty environ- the basic skills and training received by optometrists has lead ment. This was a significant problem in desert shield/storm.
to various types of co-management schemes that are deemed There are also logistics problems; solutions and replacement within the realm of optometrists. Many schemes deal with lenses can be difficult to attain while deployed.
pathological abnormalities of the eye such as cataract, dia-betes, glaucoma and low vision aids. This talk deals with the

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