The CLAO Journal

Volume 27, Number 1 -- January 2001

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Copyright 2001 Contact Lens Association of Ophthalmologists, Inc. All rights reserved.

Evaluation of the Spectral Transmittance of UV-absorbing Disposable Contact Lenses Nadia-Marie Quesnel, OD, MSc; Faten Fares, OD; Eric Verret, OD; Claude Giasson, OD, PhD 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: Increasing evidence suggesting deleterious effects of ultraviolet radiation (UVR) on the eye has prompted manufacturers to develop UV-absorbing disposable contact lenses. The spectral transmittances of a sample of these lenses were measured in order to determine if they provide adequate protection from UVR. Methods: Four types of UV-absorbing disposable lenses were studied (Acuvue [Vistakon, Jacksonville, FL], Precision UV [Wesley-Jessen, Des Plaines, IL], Specialty Sport [Specialty UltraVision, Sunnyvale, CA], and Surevue [Vistakon]). For comparison, a lens without UV-absorbing properties (Acuvue), a conventional soft lens (Permaflex UV [Cooper Vision, San Jose, CA]) and an RGP lens (Boston ES [Polymer Technology, Rochester, NY]) were also evaluated. The tested lens was placed in a silica wet cell filled with saline. Spectral transmittance was measured over the 200–800 nm waveband. Results: Each disposable lens exhibited a transmittance window in the 240–320 nm waveband. Computing indices of protection factor and safe exposure duration allowed for the assessment of the level of protection afforded by each lens. Among disposable lenses studied, the Surevue performed best with a transmittance of less than 1% in the waveband 280–348 nm and the longest safe exposure duration, while the Specialty Sport had the highest transmittance of UVB (290–315 nm). Conclusion: All UV-absorbing lenses studied provided a better level of protection from UVR exposure than lenses without UV absorber. These results will help the eyecare practitioner in prescribing the most appropriate UV-blocking lens for each patient. Back to Table of Contents

Bacterial Populations on 30-Night Extended Wear Silicone Hydrogel Lenses Lisa Keay, BOptom; Mark D.P. Willcox, PhD; Deborah F. Sweeney, PhD, FAAO; Carol A. Morris, PhD; Najat Harmis, BSc; Karen Corrigan; Brien A. Holden, DSc, FAAO 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: Ocular infection and inflammation during hydrogel lens extended wear is often associated with colonization of the lenses with bacteria. This study compares colonization of a high Dk silicone hydrogel contact lens (lotrafilcon A) worn on a 30-night extended wear basis to a low Dk HEMA-based lens (etafilcon A) worn on a 6-night extended wear schedule. Methods: The group wearing the low Dk/t soft contact lens (n = 63) replaced their lenses weekly and the group wearing high Dk/t soft contact lenses replaced their lenses monthly (n = 64). Lens allocation was assigned randomly at enrollment. Worn lenses, from one eye only, were collected aseptically and placed in sterile vials. Microbial growth on various media was enumerated and the number of colony forming units (cfu) per lens was calculated in categories of normal ocular microbiota (such as coagulase-negative staphylococci and Propionibacterium spp.) and known ocular pathogens (such as Staphylococcus aureus and gram-negative bacteria). The proportion of samples colonized with these bacteria and the extent of colonization were compared between the two groups. The proportion of sterile lenses was calculated, and the types of bacteria on each lens group were compared. Results: No differences between the low and high Dk/t Soft contact lens groups were observed in the proportion of lenses colonized by Propionibacterium spp. (48% vs 43%, P= 0.4) or coagulase-negative staphylococci (47% vs 54%, P = 0.2). Similarly, no differences were found for lenses colonized by S. aureus (0% vs 2%, P = 0.1) or gram-negative bacteria (3% vs 2%, P = 0.8). The types of bacteria isolated from the high and low Dk/t lenses were similar. There were no differences in the number of sterile samples (28% vs 27%, P = 0.8) from each group. Conclusions: These findings suggest that high Dk/t silicone hydrogel materials are colonized by similar numbers and types of microorganisms during extended wear compared to HEMA-based material. Most lenses were colonized by commensal bacteria during 30-night extended wear with high Dk/t lenses and during 6-night extended wear with low Dk/t lenses. The incidence of sterile samples was the same between the high and low Dk/t soft contact lens groups. Back to Table of Contents

Conjunctival Histologic Findings of Dry Eye and Non-Dry Eye Contact Lens Wearing Subjects Julie M. Albietz BAppSc(Optom)(Hons), PhD Purpose: To determine if contact lens wearers with dry eye (DE CL) have greater histological and inflammatory conjunctival epithelial changes compared to non-dry eye contact lens wearers (CL). Methods: Fifty-eight myopic subjects were recruited for the study: DE CL group (N=27), CL group (N=11), and control group (N=20). Contact lens groups were matched for proportions of rigid gas permeable (RGP) lenses, disposables, and conventional soft contact lenses. Dry eye was defined by McMonnies dry eye symptom survey score of 14, fluorescein break up time (FBUT) of <10 seconds, and the presence of rose bengal staining. Ocular surface samples were taken using conjunctival impression cytology to determine nucleo-cytoplasm ratio, goblet cell density (GCD), and expression of conjunctival antigens to HLA DR and CD23. Results: HLA DR and CD23 expression were significantly greater for the DE CL group compared to the CL group (P=0.0122 and P=0.0072, respectively). The CL group had a significant reduction in GCD (P=0.0001), and greater expression of ocular surface antigens to HLA DR (P=0.04) and CD23 (P=0.04) compared to the control group. Conclusions: The results of this study support the view that mechanical influences are responsible for the conjunctival squamous metaplasia changes in contact lens wear. Dry eye in contact lens wear is associated with allergic and immune mediated inflammatory processes. Back to Table of Contents

Practical Experience with a High Dk Lotrafilcon A Fluorosilicone Hydrogel Extended Wear Contact Lens in Spain Jesús Montero Iruzubieta, MD; Josep Ramón Nebot Ripoll, OD; Jesús Chiva, OD; Olga Esteban Fernández, OD; Juan José Rubio Alvarez, OD; Fabio Delgado, OD; César Villa, OD; Luis Miguel Traverso, OD Purpose: Several research studies on high Dk soft contact lens materials have been published, but little has been reported from practical clinical experience with these new materials. This study reports in-practice clinical experience with the lotrafilcon A fluorosilicone hydrogel material from a 6-month study in Spain. Methods: Eighty-five patients were dispensed lotrafilcon A lenses (Focus® NIGHT & DAY™ [CIBA Vision Corporation]) for monthly replacement by 13 investigators from eight practices. The recommended wear schedule was daily wear for the first week and then up to 6-night extended wear through the first month and up to 30-night extended wear through 6 months. Follow-up visits were at 1 week, 1 month, 3 months, and 6 months. Clinical and patient subjective data were collected at each visit. Results: Among patients who continued in the study at each visit, Snellen visual acuity (VA) of 20/25 or better was achieved by at least 96% of all eyes at all visits; lens surfaces assessments for front surface deposits, front surface wetting, and back surface debris averaged less than grade 1 (0–4 scale) for all lenses at all visits; biomicroscopy grades averaged well below grade 1 (0–4 scale) for all eyes at all visits; acceptable or optimal fit was assessed for 97% or more of all lenses at all visits. These patients rated the average overall comfort, vision, and handling above 9 (0–10 scale) at 6 months and 98% reported satisfaction with the lenses at 6 months. Eighty-two percent of patients dispensed completed the study. Seven patients were discontinued because of fit, and seven were discontinued because of positive biomicroscopy signs. Conclusions: The lotrafilcon A lens performed well clinically and it was accepted well by patients, with most practitioners recommending and most patients wearing it for up to 30 nights extended wear. Practitioners should be attentive to fit and discomfort complaints at dispensing and follow-up and may want to recommend lubricating or rewetting drops for those patients with dryness symptoms. Back to Table of Contents

Microbiological Profile of a Shipboard Environment and the Flora on Contact Lenses of Seamen Julian Thiam Siew Theng, FRCOphth; Lim Wee Kiak, FRCOphth; B.G. Lionel Lee, MPH; Donald Tan, FRCOphth; Chew Sek Jin, PhD, FRCS Purpose: The purpose of this study was to culture and identify the spectrum of organisms (and their sensitivities) that contaminate the extended wear contact lenses of seamen in their working environment. A secondary aim was to identify the most appropriate first-line antibiotic regimen to be used on seamen who sustain contact lens-related corneal keratitis on board ship. Methods: Twenty pairs of contact lenses of 20 seamen in one group and 24 pairs in another group wearing contact lenses were collected at the end of 1 week of extended wear. Groups one and two differed only in the way lenses were stored prior to culturing. All contact lenses were then brought to the microbiological lab within 24 hours for culture and sensitivity testing. Results: The most common contaminants on the contact lenses in this study were Staphylococcus epidermidis and Staphylococcus aureus, organisms resident on the normal eyelids. Enterobacter and Pseudomonas species, present in a shipboard environment, were also identified as contaminants on the contact lenses. The organisms cultured from the contact lenses correlated well with those of normal lid flora as well as from the ship environment and are probably derived from these sources. Storage in saline-containing preservatives yielded significantly less positive bacterial cultures from the contact lenses in our study. All bacterial isolates were sensitive to ciprofloxacin whereas several bacteria resistant to cefazolin and gentamicin were identified. Conclusion: The most common contaminants on the contact lenses in this study were Staphylococcus epidermidis and Staphylococcus aureus, organisms resident on the normal eyelids. Enterobacter and Pseudomonas species, which are normally present in a shipboard environment, were also identified as contaminants on the contact lenses. Ciprofloxacin is effective against all organisms identified as contaminants on the contact lenses in this study. Of all the antibiotics tested, it is probably the most suitable agent against contact lens-related keratitis under such shipboard circumstances and is thus recommended in these situations. Back to Table of Contents

Diagnosis of Hemophilia Made afterIntraoperative Bleeding during Attempted Penetrating Keratoplasty in an Elderly Patient David M. Choi, MD; Michael H. Goldstein, MD; William T. Driebe, Jr., MD Purpose: To report an unusual case where the diagnosis of hemophilia was made after attempted penetrating keratoplasty in an elderly patient. Methods: A 75 year old white male with a full-thickness corneal scar in the visual axis and a visually significant cataract OD was to undergo penetrating keratoplasty and cataract extraction with lens implantation for visual rehabilitation. There was no history of bleeding diathesis given. Results: During placement of the Flieringa ring, a progressively enlarging 360° subconjunctival hemorrhage was observed. Given the unusual bleeding, the procedure was aborted and the patient was referred to the hematology service for further evaluation. Laboratory studies revealed a diagnosis of atypical hemophilia of mild severity. Conclusions: The initial diagnosis of hemophilia in any elderly patient is unusual. This case is even more unusual as the diagnosis of a bleeding disorder was first considered after excessive subconjunctival hemorrhage developed during attempted penetrating keratoplasty. Back to Table of Contents

Comamonas acidovorans Keratitis in a Hydrogel Contact Lens Wearer Isabel Lema, MD, PhD; Manuel Gómez-Torreiro, MD, PhD; Mª Teresa Rodríguez-Ares, MD, PhD Purpose: To present an unusual case of keratitis in a patient who wears hydrogel contact lenses that are replaced on a monthly basis. The agent isolated was Comamonas acidovorans, a species of Pseudomonas. Methods and Results: A 40-year-old patient who wears hydrogel contact lenses that are replaced on a monthly basis presented with a red eye. The patient reported that the eye had been red for 2 days. A peripheral corneal stromal infiltrate was found and Comamonas acidovorans was isolated in culture. The patient was initially treated with high-dose gentamicin. After the results of cultures and sensitivity studies were obtained, she was given ciprofloxacin, leading to the remission of the case. Conclusions: Comamonas acidovorans should be considered as a possible agent of keratitis in hydrogel contact lens wearers—a culture and sensitivity studies may be indicated. Back to Table of Contents

Editorial: Contact Lenses, Refractive Surgery, and Spectacles: Competing Modalities or Something Else? Over the last few years the number of contact lens wearers in the United States has steadily increased and now stands at over 30 million. The growth in the contact lens market was made possible by a number of factors including an increase in the number of contact lens options for patients. Both new and former contact lens wearers have been attracted by the introduction of daily disposable contact lenses, the availability of frequent replacement contact lenses—including toric and bifocal lenses—in a broad selection of parameters, as well as new silicone hydrogel contact lens materials. Likewise, there have been important developments in lens care systems, with the promise of improved efficacy and patient compliance with these simplified systems. These developments combined with new strategies to treat contact lens complications have resulted in an increase in the number of people who can be successfully fit with contact lenses and has enabled former contact lens failures to return to lens wear. The number of refractive surgery procedures has also increased significantly over the last two years, even though the estimate of 1.5 million LASIK procedures for the year 2000 has probably not been met. Important developments in the area of refractive surgery have facilitated its growth. Improvements in microkeratomes, the introduction of new lasers, and new refractive procedures have resulted in expanded parameters, improved results, and decreased complications. Future advances will result in improving and maximizing patient outcome with better predictability and even fewer complications. Are these two well-proven modalities of vision correction truly in competition? Or are they complementary? If one looks at the demographics, our contact lens wearers are younger and predominately female, while the refractive surgical patient is older (average age: 35–40 years), and fairly evenly split between males and females. There are individuals who prefer to have their vision corrected by nonsurgical modalities and would only consider contact lenses or glasses. On the other hand, there are individuals who do not want to be dependent on contact lenses and/or glasses and are looking for a more permanent means to correct their vision. In addition, there are individuals who may move from one modality to the other, first utilizing contact lenses, but then considering the possibility of refractive surgery as they get older and start to experience problems or discomfort with their contact lenses. Furthermore, there are patients who have had refractive surgery, but still need some form of vision correction, either full-time or on an intermittent basis. Most published statistics for LASIK report 85–100% of the patients achieve 20/40 vision but only 65–80% achieve 20/20.1,2 Thus, many of these patients may still need a pair of glasses or even contact lenses for a specific visual task such as driving at night. In addition, since we are dealing with many patients who are over 40, even with a monovision surgical procedure, they may still need reading glasses for certain tasks. Thus, as comprehensive ophthalmologists we should refrain from considering refractive surgery and contact lenses as two competing modalities and offer our patients both options, as well as glasses. By gaining the expertise in all three areas—spectacles, contact lenses, and refractive surgery—we can better discus the various options and then recommend the selected method of vision correction to meet the needs of our patients. This approach will better serve our patients and create a more loyal bond with them. Gaining the necessary expertise to achieve this goal is within the reach of all comprehensive ophthalmologists. Attending the CLAO Annual Meeting is one way to either start the process or to continue one's education. This year's Annual Meeting has expanded the educational opportunities for physicians and their staffs at all experience levels in the areas of contact lenses, optical dispensing, practice management, and refractive surgery. I look forward to seeing you in Las Vegas. Peter C. Donshik, MD Editor in Chief The CLAO Journal References 1. Waring GO, Carr JD, Stulting RD, et al: Prospective randomized comparison of simultaneous and sequential bilateral laser in situ keratomileusis for the correction of myopia. Ophthalmology 1999;106:732-738 2. Montes M, Chayet A, Gomez L, et al: Laser in situ keratomileusis for myopia of –1.50 to –6.00 diopters. J Refract Surg 1999;15:106-110. Back to Table of Contents

E-Mail: CLAOJrnl@aol.com

Copyright 2001 Contact Lens Association of Ophthalmologists, Inc. All rights reserved.