The CLAO Journal

Volume 26, Number 4 -- October 2000

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Copyright 2000 Contact Lens Association of Ophthalmologists, Inc. All rights reserved.

Clinical Characterization of Spherical Post-lens Debris Associated with Lotrafilcon High-Dk Silicone Lenses Kathryn Dumbleton, MSc, MCOptom; Lyndon Jones, PhD, FCOptom; Robin Chalmers, OD; Donna Williams-Lyn, OD, PhD; Desmond Fonn, MOptom Purpose: Experience with high Dk silicone hydrogel lenses has revealed post-lens debris, which is characterized by the appearance of spherical, translucent particles referred to as "mucin balls." The objectives of this analysis were to characterize the presence of mucin balls, determine whether any ocular characteristic predicts the development of mucin ball debris, and determine whether there is any association between mucin balls and the ocular response to contact lens wear. Methods: Ninety-two subjects wore lotrafilcon A lenses on an extended wear basis for up to 30 nights and were followed for 6 months. Mucin balls were graded on a 0 to 4 scale at three visits. Subjective ratings and biomicroscopic appearance were recorded at all visits. Results: Mucin balls were observed in 70% of subjects at one or more visits, and 29% of subjects at all three visits. There was no change in the mean grade of mucin balls over time. Mucin balls were graded > 1 in 20% of eyes, > 2 in 6% of eyes, and > 3 in 2% of eyes. Subjects who exhibited mucin balls at each clinical visit had significantly steeper keratometry readings along the flatter meridian (44.3 D) than those who never exhibited mucin balls (42.9 D, P<0.0001). The percentage of subjects who "never" use lubricating drops was higher in the subjects with mucin balls (P = 0.0014). No association was found between mucin ball observation and biomicroscopic appearance, inflammatory responses, or subjective responses. Conclusions: The presence of mucin balls does not appear to be detrimental to contact lens wear. Eyes with steeper corneal curvature were significantly more likely to present with mucin ball debris, indicating they may be a function of lens fit. Clinical factors that may be modified in order to manage the more severe presentation of mucin balls are the use of lubricating drops and the number of nights extended wear schedule. Back to Table of Contents

Evaluation of a New System of Lens Parameter Selection and Comparison of Traditional vs One-Step Lens Care Systems for Aspheric High-Dk RGP Contact Lenses John de Brabander Optom, MSc; Jan H.C. Kok MD, PhD; Rudy M.M.A. Nuijts, MD, PhD Purpose: We investigated the value of newly developed systems for parameter selection on the performance of high Dk rigid gas permeable (RGP)contact lenses with a spheric-aspheric design made of Boston Equa material in normal daily wear conditions. A comparison was also made between the safety and efficacy of a traditional care system vs a one-step chemical care system during the follow-up period of 1 year. Methods: A total of 66 patients were randomly assigned to traditional and newly developed systems for computing the back optical zone radius (BOZR) and the total diameter (TD) of the lenses. Evaluation parameters incorporated assessment of fit, visual acuity, wearing time, comfort, and lens condition. Results: The traditional method of computing the BOZR, using a method based on flat-K, predicted the BOZR successfully in 83% of the cases. Corneal topometry reached a lower, but not significantly different (P > 0.01) value of 75% correct prediction of BOZR. Analysis of the differences in eccentricity (E) values between quadrants per eye was a significant (P< 0.001) factor in fault predictions in the topometric system. A newly developed guide for TD selection performed, with 90% correct predictions, significantly (P < 0.01) better than a traditional method (72%) based on corneal diameter on supraversion. No significant differences (P > 0.05) were found in the capabilities of care systems (a traditional care system using a surfactant cleaner vs a one-step solution) to keep the lenses in proper condition and without deformation, over the 1 year follow-up period. The final success rate was 85%. Conclusions: Although high Dk RGP contact lenses can be fit and used with a 85% success rate using advanced systems for determining the BOZR and TD, it remains necessary to evaluate the fit before dispensing high Dk RGP lenses in 15% of the cases. The one-step solution used in this study was a good starting point for lens care. If needed, surfactant cleaning in the traditional care system can be done without the risk of lens deformation. Back to Table of Contents

Comparative Study of the Hydration of Hydrophilic Contact Lenses by Refractive Index and Gravimetry Antonio López Alemany, MD, PhD, OD; Miguel F. Refojo, DSc Purpose: To compare the percent hydration by wet weight of hydrogel contact lenses given by the manufacturers with the values obtained using the refractive index and the gravimetry methods. Methods: We used a Valentine refractometer to determine the refractive index of new hydrogel contact lenses at equilibrium swelling in the original solution and container. From the refractive indexes we then obtained the percent hydration of the lenses using a previously prepared graph of refractive index vs percent hydration of saccharose in a phosphate buffer solution (pH 7.0). We used an electronic analytical balance of 0.01 mg resolution to obtain the weights of new lenses when dry and at equilibrium swelling dry, and calculated the percent hydration of the lenses from the difference of the wet and dry weights. Results: The hydration values of the contact lenses obtained from the index of refraction differed more than those obtained by gravimetry from the values given by the manufacturers. Acuvue lenses were an exception—the difference for them was negligible. Conclusion: Gravimetry is more accurate, but more cumbersome and time-consuming than the index of refraction for the determination of the hydration of the hydrogel contact lenses. However, when a fast and easy method is required to obtain the approximate hydration of hydrogel contact lenses, the use of the refractive index method can give acceptable results for most applications. Back to Table of Contents

A Comparison of Contact Lens-related Complications in Various Daily Wear Modalities Jeanine K. Suchecki, MD; William H. Ehlers, MD; Peter C. Donshik, MD, FACS On-Line Dialogue: Click the mailbox to submit questions or comments on this article. Please include article title or author as well as your name and postal address. Purpose: To determine the incidence of contact lens-related complications in various daily wear contact lens modalities. Methods: The charts of 138 daily wear contact lens patients (35 daily disposable, 34 two week replacement, 34 frequent replacement, and 35 conventional daily wear lens users) were reviewed for subjective and objective contact lens problems. We also looked at two subgroups: first time lens wearers and patients with previous lens-related problems. The rate of lens related complications were calculated as events per person per year (E/P/Y) of lens wear for each year and for the total 3-year study. The percentage of patients in each group who experienced any complication was calculated. We also compared the complication rate for the groups in our current study to the rates calculated for disposable extended wear and conventional extended wear patients from our previous study. Results: We found that the E/P/Y were significantly lower for daily disposable lens wearers, but no significant differences were noted for all other lens wear modalities. There was a trend in most groups toward decreased numbers of complications in the second and third years of lens wear. Of the 23 individual signs and symptoms that were analyzed, three occurred most frequently among daily disposable lens wearers, two were most common in the 2-week replacement group, four occurred most often in frequent replacement patients, and eight were most frequent in conventional daily lens wearers. (In three categories, there were two groups with ties for the highest rate of occurrence, and two categories with zero rates for all groups.) Most of the observed differences in complication rates for individual signs and symptoms did not reach the level of statistical significance. Conclusions: Daily disposable lens wearers had the lowest overall complication rate. Back to Table of Contents

Evaluation of the Zebra 2000 (Z-10) Breger Vision Bifocal Contact Lens Vivien M. Smith, OD; Bruce H. Koffler, MD; Gil Litteral, FCLSA Purpose: Evaluate the ZEBRA 2000 (Z-10) bifocal contact lens on presbyopic and aphakic patients. Methods: Thirty-eight patients, 37 presbyopes and one aphake, were fit in the Z-10 and evaluated for 6 months. Results: Twenty patients (53%) completed 6 months of contact lens wear. Ten (26%) discontinued due to lens related problems, three (8%) discontinued due to other health problems, and five (13%) were lost to follow-up. Average refits per eye were 1.75. Average distance visual acuity was 20/25; average near visual acuity was J1.6; average wear time, 11 hours. Patient satisfaction was rated good in comfort and vision and fair in nighttime glare by patients' subjective evaluation. Conclusions: The ZEBRA 2000 (Z-10) can be a useful addition in fitting the general presbyopic patient population. Back to Table of Contents

Assessment of Ophthalmology Residents' Contact Lens Training Damien C. Macaluso, MD; Mark Andre, FAAO; Patrick J. Caroline, FAAO; Eric B. Suhler, MD; Larry F. Rich, MD On-Line Dialogue: Click the mailbox to submit questions or comments on this article. Please include article title or author as well as your name and postal address. Purpose: To characterize the nature and duration of contact lens training in ophthalmology residency training programs and to ascertain the comfort level of residents in fitting various types of contact lenses and in dealing with common contact lens-related complications. Methods: Surveys were mailed to 126 ophthalmology residency program directors/coordinators and requested to be distributed to 1,381 ophthalmology residents. The questionnaire addressed issues related to contact lens training, hours of clinical and didactic training, comfort with fitting a variety of different types of contact lenses and dealing with common contact lens-related complications, and plans for incorporation of contact lens dispensing into future practice. Results: Two hundred and forty-nine residents (18%) responded from 84 programs (67%). Most programs (87%) have some form of supervised contact lens training, frequently conducted by an optometrist (61% of programs), that consists of 20 hours or less of clinical experience and 20 hours or less of didactic training. A majority of the responding graduating residents (66%) feel comfortable fitting spherical soft contact lenses, while less than half of all residents feel comfortable fitting any other type of contact lens. In addition, most residents (65%) feel comfortable diagnosing and treating common contact lens-related complications. Conclusions: Most ophthalmology residency programs offer some form of supervised contact lens training which allows a majority of residents to feel comfortable fitting only spherical soft contact lenses, while also dealing comfortably with most contact lens-related problems. A comparison with previous data suggests increasing comfort with fitting most types of contact lenses over the last decade. Back to Table of Contents

The Impact of Variable Tint Optics (Transitions® Gray) on Vision-related Quality of Life in Normal Volunteers: A Randomized Clinical Comparison in a Warm Climate Thomas J. Pusateri, MD; Philip T. Lavin, PhD; Christopher J. Baldy, PhD, ABOC; Karen A.F. Copeland, PhD; Mary Sequiti, LDO, NCLE, ABOC Purpose: A randomized crossover comparison of Transitions® Gray variable tint optics (VTO) vs clear and fixed-tint lenses was undertaken to evaluate the impact of VTO on vision-related quality of life (VRQOL) in a warm climate. Methods: Fifty-nine patients were randomized to one of four lens crossover groups: Transitions—clear; clear—Transitions; Transitions—fixed-tint; fixed-tint—Transitions. Each lens was worn for 30 days. VRQOL was measured using a newly developed and validated questionnaire instrument—the Transitions VRQOL. Changes in visual acuity were assessed by functional exam. Results: Overall, Transitions was associated with the greatest improvement in VRQOL relative to clear and fixed-tint lenses without compromise in acuity. Transitions proved statistically superior to clear lenses, most notably in vision comfort both indoors and outdoors. Seventy percent of all patients selected Transitions as their primary lens at the end of the study. Conclusions: Transitions brand VTO offer patients significant and clinically meaningful improvements in VRQOL superior to clear lenses. VRQOL assessments provide clinicians with valuable information above and beyond visual acuity to help optimize lens product selection and enhance patient satisfaction. Back to Table of Contents

Editorial: Contact Lens Residency Training: Progress and Challenges A decade ago ophthalmology residency training programs devoted little time or emphasis to the non-surgical, non-diagnostic aspects of what was needed for an ophthalmic practice. The surgical arena and diagnostic expertise were the hallmarks of residency education. Today, with the shift to a comprehensive ophthalmology practice, additional areas of ophthalmology expertise are needed to deliver appropriate eyecare. Knowledge of contact lenses and optical dispensing are requirements in today's competitive environment. In the last few years there has been a recognition by leaders in academic ophthalmology as well as the American Academy of Ophthalmology that contact lens education is an important aspect of residency education. For many years CLAO has championed the role of contact lenses in ophthalmology. CLAO has advocated that every resident should be proficient in contact lens knowledge and fitting techniques. In an attempt to fill residency contact lens educational needs, CLAO has offered regional contact lens seminars in major metropolitan areas. In addition, CLAO, in cooperation with the Association of University Professors of Ophthalmology and the American Academy of Ophthalmology, has developed the CLAO Residents Contact Lens Curriculum Manual and Library Package. This has been introduced in over 120 residency programs. It provides basic, practical knowledge that each resident should have in the field of contact lenses. The importance of contact lens knowledge is evident in that, even with the recent interest and popularity of refractive surgery, the number of contact lens patients has continued to increase over the last few years. Contact lenses are now used by over 25% of patients requiring vision correction. As the number and variety of contact lenses has expanded, an understanding of these modalities should be a requirement for every graduating ophthalmology resident. Macaluso and coworkers (1), in their article published in this issue of The CLAO Journal, were able to gain information from two-thirds of the ophthalmology training programs in the United States. While the good news is that most residency programs (87%) do offer supervised clinical training, and 66% of the graduating residents were comfortable fitting spherical and soft contact lenses, the bad news is that less than half the residents surveyed felt comfortable fitting spherical rigid gas permeable contact lenses, or even soft toric lenses. However, it is encouraging that the percentage of residents who felt comfortable in fitting the various types of contact lenses was higher in this study than it was in a previous study conducted by Asbell and Wittman (2). In this era of comprehensive ophthalmology, it would behoove ophthalmology residency training programs to increase their emphasis on training residents to fit contact lenses. While there has been some improvement over the last 7 to 10 years, there is definitely a lot of work that still needs to be done. Hopefully, the presence of the CLAO Residents Contact Lens Curriculum Manual will serve as a teaching core to increase the emphasis and improve residents' knowledge and confidence in fitting all modalities of contact lenses. Peter C. Donshik, MD Melvin I. Freeman, MD Editor in Chief Associate Editor The CLAO Journal The CLAO Journal References 1. Macaluso DC, Andre M, Caroline PJ, et al: Assessment of ophthalmology residents' contact lens training. CLAO J 2000;26:221–224. 2. Asbell PA, Wittman N: Residency training in contact lenses: A survey. CLAO J 1996;22:168–171. Back to Table of Contents

E-Mail: CLAOJrnl@aol.com

Copyright 2000 Contact Lens Association of Ophthalmologists, Inc. All rights reserved.