The CLAO Journal

Volume 25, Number 3 -- July 1999

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Copyright 1998 Contact Lens Association of Ophthalmologists, Inc. All rights reserved.

Giant Papillary Conjunctivitis in Frequent Replacement Contact Lens Wearers: A Retrospective Study Ania D. Porazinski, MD Peter C. Donshik, 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: We conducted a retrospective study of 47 patients who wore frequent replacement contact lenses on a daily-wear basis to determine the incidence of giant papillary conjunctivitis (GPC) and to assess the potential risk factors that may predispose frequent replacement contact lens wearers to develop GPC. Methods: We reviewed the records of patients with no prior contact lens experience who were fit with frequent replacement contact lenses from September 1993 to February 1997. Results: Forty-seven of 260 patients met the requirements for inclusion in the study. Ten (21.27%) patients had developed GPC. The incidence varied with the frequency of contact lens replacement. The contact lens replacement schedule ranged from 1 day to 12 weeks. In those patients replacing their contact lenses every 4 weeks or at a longer interval, the incidence of GPC was 36%, while for patients who replaced their lenses more frequently, the incidence was 4.5%. Coated contact lenses were also more common among patients who replaced their lenses at 4 weeks or longer (P = 0.23). A significantly greater number of patients in the GPC group incorporated enzymatic cleaning into their contact lens care system (P = .0004). A history of allergy was more prevalent in patients who developed GPC and was stastistically significant (P = .012). There was no significant difference found between the groups for age, gender, average daily wearing time, FDA classification of contact lens material, time in contact lenses from fitting to diagnosis or last follow-up period, or the parameters and fitting characteristics of the contact lenses. Conclusion: The frequency at which patients replace their contact lenses appears to be an important variable in developing GPC. Although frequent replacement contact lenses do not eliminate GPC, patients on a 1-day to 3-week replacement cycle had a significantly lower risk of developing GPC than patients who replaced their lenses at longer intervals. Lens coating was present less often on contact lenses replaced daily and up to 3 weeks. For patients who are at high risk for GPC, replacing lenses at intervals ranging of one day to two weeks appears to offer a better strategy for avoiding GPC than incorporating enzymatic cleaning into their lens care system. Back to Table of Contents

Hydrogel Contact Lens Dehydration and Oxygen Transmissibility Nathan Efron, PhD, DSc, Philip B. Morgan, PhD Purpose: Oxygen transmissibility is a key determinant of the physiological response of the cornea to contact lens wear. Because transmissibility is related to hydrogel water content, we conducted a study to determine the change in water content during lens wear and to quantify the impact any such change would have on transmissibility. Methods: In a double masked clinical investigation, two subjects each wore 17 different pairs of contact lenses. Water content was measured before lens wear at 35°C and immediately after 4 hours of contact lens wear. Contact lens oxygen transmissibilities were calculated on each occasion. Results: The absolute changes in water content for the 17 lenses varied from +0.5% to -5.3%. For some lenses, this change in water content altered the lens oxygen transmissibilities to a clinically significant degree. The changes in water content and oxygen transmissibilities were greatest with FDA Group IV lenses. Conclusions: Dehydration during contact lens wear can alter the oxygen transmissibility of hydrogel lenses, and in some situations, this factor may be clinically significant. Back to Table of Contents

Predicting RGP Daily Wear Success Kenneth A. Polse, OD, MS Andrew D. Graham, MS Robert E. Fusaro, PhD Cheslyn M. Gan, OD Reuben K. Rivera, OD, MS Judy S. Chan, OD, MS Nancy A. McNamara, OD, PhD Timothy S. Sanders, OD Purpose: While most clinicians agree that fitting of rigid gas permeable (RGP) lenses is the preferred treatment strategy for some types of patients, many patients have difficulty adapting to full-time daily wear of these lenses. The Contact Lens Extended Wear Study (CLEWS) is a randomized, controlled clinical trial in which subjects are first adapted to full-time RGP daily wear prior to randomization to either high or medium oxygen transmissibility (Dk/L) RGP lenses for 12 months of extended wear. The CLEWS pre-randomization data provide an opportunity to examine the reasons some patients fail to adapt to RGP daily wear and to determine whether a patient's demographic, historical, and ocular characteristics can be used to predict RGP daily wear success. Methods: From 1,809 individuals who expressed interest in RGP lenses, 411 subjects passed the CLEWS screening criteria and were fit with high Dk lenses (mean Dk = 92 x 10-11 [cm2/sec][mL 02/mL x mmHg]). The fitting strategy included minimum apical alignment, lid attachment, centration, and average lens diameters of 9.2 mm. Success was defined as a minimum of 14 hours per day without adverse ocular responses that would contraindicate either full-day daily wear or extended wear. Results: Of the 411 subjects, 286 (69.6%) were successful with RGP extended wear. Among the 125 failures, 50 were based on clinician findings (e.g., cornea, vision, compliance), while 75 subjects chose to discontinue wear because of unacceptable comfort or poor vision. Multivariate linear logistic regression modeling shows that younger patients with greater corneal curvature (K) and less predicted residual astigmatism have a higher probability of RGP daily wear success. Conclusions: Our study showed that RGP lenses can be fit with a relatively high rate of success and that many of those patients who elect to discontinue RGP daily wear report unacceptable comfort as the primary reason. We propose a Bayesian statistical method that will assist clinicians in selecting those candidates for RGP daily wear who are most likely to adapt successfully. Back to Table of Contents

Ptosis Associated with PMMA/Rigid Gas Permeable Contact Lens Wear David Jupiter, OD James Karesh, MD Purpose: Contact lens wear has the potential to cause an acquired non-senile blepharoptosis. Ptosis can result from rigid gas permeable (RGP) contact lens wear due to contact lens migration, inflammation, and undetermined causes. The purpose of this article was to investigate the occurrence of ptosis without obvious cause in a young and middle aged RGP contact lens wearing population. Methods: We fit sixty-four patients (128 eyes) with RGP contact lenses over a fifteen month period (7/1/96 to 9/10/97) and present a series of case reports of five young and middle aged RGP contact lens wearers who developed ptosis without obvious cause during the study period. Results: Five patients (6 eyes [4.7%]) in our study developed non-senile acquired ptosis. Four patients had a unilateral ptosis, and one patient had a bilateral ptosis. Conclusions: As in other other studies, we found that a significant percentage of RGP contact lens wearers developed ptosis, which is suspected to be related to RGP contact lens wear. One possible explanation is the lens removal procedure of pulling laterally on the eyelids followed by a harsh blink. However, other causes may exist such as the constant rubbing of the lens edge against the palpebral conjunctiva. Back to Table of Contents

Diagnostic Bitoric Rigid Gas Permeable Contact Lenses Masayoshi Kajita, MD Setsuko Ito, MD Ayako Yamada, MD Yumiko Ito, MD, Keiichiro Kato, MD Purpose: To simplify the fitting of bitoric rigid gas permeable (RGP) contact lenses. Methods: We prescribed bitoric RGP lenses using two kinds of diagnostic lenses at random. One type of lens was a diagnostic polymethylmethacrylate (PMMA) spherical lens and the other was a diagnostic RGP bitoric lens. Results: The bitoric RGP lenses that were prescribed using a diagnostic bitoric lens required fewer parameter changes compared with the bitoric RGP lens prescribed using a diagnostic PMMA spherical lens. Conclusions: The diagnostic RGP bitoric lens simplifies the prescription of bitoric RGP lenses and is very useful in fitting astigmatic corneas. Back to Table of Contents

Incidence of Contamination of Preserved Saline Solutions During Normal Use Deborah F. Sweeney, PhD, BOptom, FAAO Mark D.P. Willcox, PhD, BSc Nicollette Sansey, BSc, DipEd Carol Leitch, BSc, Grad.Dip.Biotech Najat Harmis, BAppSc Reginald Wong, FIS Brien A. Holden, BAppSc, PhD, LOSc, FAAO, DCLP, DSc Purpose: To ascertain the incidence of microbial contamination of preserved contact lens saline solutions with normal patient use. Methods: Eight different brands of preserved saline were dispensed to 40 patients attending optometric practices in the Sydney area. After specific periods of time (7 to 28 days), the samples were collected and the solution bottle nozzles and contents underwent microbial analysis. Results: The overall contamination rate was approximately 26% for contents only and 55% for nozzles of preserved saline solutions. This rate remained constant for all periods of use. Coagulase-negative Staphylococci were most frequently isolated. No Acanthamoebae were isolated. Saline preserved with ethylene-diamine-tetraacetic acid (EDTA) in conjunction with sorbic acid showed the highest percentage of sterility. Conclusions: The results of this study show that preserved saline became contaminated with gram-positive bacteria. This is in contrast to our previously published paper using unpreserved saline, where contamination was predominantly with gram-negative bacteria. The overall contamination rates with preserved saline were lower than for unpreserved saline. Back to Table of Contents

Clinical Performance of an Innovative Back Surface Multifocal Contact Lens in Correcting Presbyopia Craig Woods, PhD, MCOptom, FAAO David Ruston, BSc, MCOptom, FAAO Tony Hough, BA Nathan Efron, DSc, FVCO, MCOptom, FAAO Purpose: This prospective study was designed to subjectively and objectively evaluate the performance of an aspheric multifocal back surface rigid gas permeable (RGP) contact lens. The multifocal element of this lens design consisted of an aspheric optical zone that varied according to the patient's ametropia, corneal topography, and required reading addition. Methods: We fit 28 presbyopic subjects with an aspheric multifocal back surface RGP contact lens (age range: 45 to 68 years). Reading additions ranged from +0.75 D to +2.50 D. Subjects were assessed initially and at 2, 6, and 12 weeks for ocular changes, visual performance, and subjective responses. Results: We required 116 RGP lenses to achieve an acceptable fit and visual acuity in 28 subjects (55 eyes). At the final visit, the distance logMAR acuity with the multifocal contact lens (+0.12 ± 0.10) was not statistically different (t= -0.623, P= 0.5388) from spectacle acuity at the initial visit (+0.10 ± 0.12). The near logMAR acuity with the multifocal contact lens at the final visit (0.36 ± 0.12) was not statistically different from that for near acuity with spectacles at the initial visit (0.33 ± 0.13). No slit lamp signs worsened during the study. A reduction in myopia of 0.67 D was noted by the final visit. Spectacle blur was noted if the acuity at the initial refraction was compared to the acuity with the same refraction at the final visit (t= -3.287, P= 0.0028) but not when the refractive changes were incorporated (t= 1.058, P= 0.3127). All subjects rated the performance of the lenses very highly: comfort, 86%; distance acuity, 83%; near acuity, 73%; and stability of vision, 74%. Twenty-four subjects (86%) chose the multifocal contact lens as their preference. Conclusion: We demonstrated that a multifocal design is able to provide acceptable distance and near correction for presbyopic patients. The aspheric geometry required can be optimized for a given patient by considering his/her degree of ametropia, as well as the corneal topography. Back to Table of Contents

Penetration of Topical Ciprofloxacin by Presoaked Medicated Soft Contact Lenses Defne Kalayci, MD Nursabah Basci, PhD Selim Kortunay, MD Hikmet Hasiripi, MD Atilla Bozkurt, MD Purpose: To assess the penetration of topical ciprofloxacin by a presoaked medicated disposable soft contact lens without topical drop administration. Methods: Disposable soft contact lenses were presoaked in 0.3 % topical ciprofloxacin (Ciloxan, Alcon Laboratories, Fort Worth,TX) for 10­12 hours. Presoaked lenses were placed on the eyes of patients with senile cataracts for 3 hours in group A, 5­6 hours in group B, and 8­12 hours in group C prior to their scheduled lens extraction surgery. Aqueous humor samples were drawn by paracentesis during the operation. Ciprofloxacin concentrations were determined by high pressure liquid chromatography-fluorescence detection. Results: The mean ciprofloxacin concentration was 2.70 ± 0.98 µg/mL in group A, 1.22 ± 1.0 µg/mL in group B, and 0.5 ± 0.2 µg/mL in group C. Conclusions: Penetration of topical ciprofloxacin is enhanced through a presoaked disposable soft contact lens, and at 3 hours therapeutic levels are obtained. Significant levels of ciprofloxacin are retained through 8­12 hours. This mode of treatment may increase patient compliance compared to frequent topical drop administration, and as a consequence, assure efficient treatment of keratitis, at least for the first 3 hours. Back to Table of Contents

Editorial Extended Wear Revisited Among contact lens wearers there remains a significant interest in extended wear. Many contact lens patients would like to eliminate or reduce the amount of time spent on lens care. Refractive surgery is a viable option for some of these patients, but it is not for everyone. The number of contact lens wearers has increased from approximately 25,000,000 to 30,000,000 over the last few years as has the number of refractive surgical procedures (to just under a total of one-half million). Although refractive surgery has grown, it has not had a significant impact on the contact lens market. Extended wear remains an area of interest among contact lens investigators. But alongside the attraction to extended wear, there remains a fear of the potential complications, particularly ulcerative keratitis. The landmark articles1,2 that brought to our attention the association of ulcerative keratitis with overnight wear of contact lenses have instilled a cautiousness in both practitioners and patients. In the last 15 years our knowledge of the complications associated with extended wear has greatly increased. In general terms, there appears to be two areas that must be addressed for successful extended wear. One is the relationship of the contact lens with the ocular surface and the other is the oxygen transmissibility of the contact lens. The introduction of disposable contact lenses has decreased the incidence of ocular surface problems (i.e., decreasing lens deposit formation and subsequent spoilage of the contact lens, thus decreasing the irritative or immunological effect on the conjunctival and corneal surfaces). Studies by Poggio and Abelson,3 Hamano and coworkers,4 and Boswall and coworkers5 have shown that the complications associated with conventional contact lens wear such as itching, burning, dryness, blurred vision, and foreign body sensation are significantly decreased in disposable contact lens wear. In addition, the incidence of giant papillary conjunctivitis (GPC) with disposable extended wear is reduced compared with conventional extended wear. In this issue of The CLAO Joumal, Porazinski and Donshik report that the incidence of GPC is significantly reduced in patients who replace their contact lenses at intervals of 3 weeks or less compared with individuals who replace their contact lenses at intervals of 4 weeks or longer. Thus, the frequent replacement of the contact lens appears to be beneficial to the ocular surface. However, a serious potential complication of extended wear contact lenses is the development of ulcerative keratitis. Important studies by Schein and associates1 demonstrated that the relative risk for ulcerative keratitis was 10-15 times higher with overnight wear of soft contact lenses compared with daily wear. Poggio and associates2 in a corollary study demonstrated that the annualized incidence of ulcerative keratitis with soft contact lenses was 20.9 per 10,000 for extended wear compared with 4.1 per 10,000 for daily wear. The introduction of disposable contact lenses did not appear to affect the overall incidence of ulcerative keratitis. Studies by Poggio and Abelson3 and Nilsson and Montan6,7 showed that the overall incidence of ulcerative keratitis was similar for both disposable and conventional extended wear lenses. However, in both studies, the data appear to suggest that the severity of ulcerative keratitis was much less with disposable compared to conventional extended wear contact lenses. Ulcerative keratitis with disposable lenses occurred more often in the peripheral cornea rather than in the central cornea.3,6,7 In addition, it appeared that the organisms responsible for ulcerative keratitis in patients wearing disposable contact lenses were more likely to be gram-positive rather than gram-negative bacteria.8,9 It it not clear yet how the use of new, ultra-high-Dk lenses for extended wear will affect this picture. In 1994, Hamano and coworkers4 reported on complications induced by conventional and disposable contact lenses in Japan. There were no ulcers reported during this study. The major complication was superficial punctate keratitis, with the lowest rate of complications in the daily disposable soft contact lens group of patients (2.5%). Disposable extended wear lenses had an overall complication rate of only 4.9%, which was lower than the complication rate for both conventional soft contact lenses and RGP contact lenses. The other important factor that has to be considered in extended wear is corneal hypoxia. First, contact lens associated corneal hypoxia increases Pseudomonas adherence to exfoliated epithelial cells from the human cornea.10,11 Second, the cornea needs enough oxygen to conduct its normal metabolic processes. Thus, the introduction of ultra-high-Dk soft contact lenses should eliminate the contact lens associated hypoxia and decrease or eliminate the factors responsible for Pseudomonas binding. Thus, this should decrease the conditions conducive to developing Pseudomonas ulcerative keratitis. Another finding that has been noted in extended wear contact lenses is the occurrence of central corneal thinning. In this issue, Ren and coworkers have shown that extended wear of RGP contact lenses in the rabbit model significantly decreases central corneal epithelial proliferation. They hypothesized that contact lens related hypoxia may be responsible for this inhibition. While the central epithelial proliferation is decreased, corneal limbal and conjunctival epithelial cells show active proliferation perhaps in an attempt to compensate for the suppression of the central area. This raises the question, as proposed by the authors, that extended wear may continually stimulate limbal stem cells, which may have a deleterious affect with long-time extended wear. The clinical question that has to be answered is whether this phenomena occurs in individuals wearing extended wear contact lenses. Is it related to frequency of contact lens replacement, i.e., whether a lens is worn continuously for 1 week, 2 weeks or 4 weeks? Does the stimulation for proliferation continue after adaptation of the contact lens? Is there a new, regulatory mechanism that may then decrease the stimulus for proliferation, or does proliferation continue and have a potential adverse affect for the long-term health of the cornea. As we approach the millenium, we look back and see that there have been tremendous advances in the field of contact lenses in general and in extended wear in particular. The advent of disposable contact lenses for both daily as well as extended wear has significantly reduced the complications associated with contact lens wear, has decreased the number of patients who have dropped out of contact lenses, and has been one of the major factors for increasing the number of contact lens wearers. The introduction of high-Dk soft lenses for both daily wear and extended wear is an important contribution and has the potential for making extended wear even safer. The correct schedule of wearing time and lens replacement has yet to be determined. Further studies are necessary to give us the data to make these decisions and meet our patients' expectations of safe, clear vision 24 hours a day. Peter C. Donshik, MD Editor-in-Chief The CLAO Journal Back to Table of Contents

E-Mail: CLAOJrnl@aol.com

Copyright 1998 Contact Lens Association of Ophthalmologists, Inc. All rights reserved.