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C.J. Clark, W.H. Ayliffe, A. Dharmasena, S. Khemika, M. Guillon, N. Mahalingham; Microbial Keratitis in Contact Lens Related Ulcers . Invest. Ophthalmol. Vis. Sci. 2005;46(13):925.
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Purpose:To evaluate risk factors contributing to the occurrence and severity of microbial keratitis in contact lens wearers, its management and effect on corneal endothelium. Methods: 32 patients with contact lens related corneal ulcers (CLRU) were studied prospectively over two years. Ulcers were classified as mild, moderate or severe using: presence or absence of anterior chamber reaction; position of the ulcer in relation to the visual axis; and size of the ulcer. A case study questionnaire was employed and the subjects were referred for Confocal Microscopy of the corneal endothelium after ulcer healing. Results: CLRU: 12.5% extended wear, 4.2% annual, 4.2% 3–monthly disposable, 70.8% monthly disposable and 8.3% daily regimen. A one–step care system led to an increased risk of complications. 44.4% CLRU were mild, 33.3% moderate and 22.2% severe. 59% were central and 41% were peripheral. GPs had commenced antibiotic therapy in 18.5% of the ulcers. Eight culture positive results from the corneal scrapes: 5/8 Pseudomonas, 1/8 Klebsiella, 1/8 Serratia Liquefaciens, 1/8 Herpes Simplex. 90% were treated with Ofloxacin (40% in combination with Cefuroxime; 18% with Predsol). One patient was prescribed oral Ciprofloxacin and one Acyclovir. On treatment 68% showed an improvement of visual acuity, 19% remained unchanged and 14% showed deterioration. On resolution, 2 patients had Deep Lamellar Keratoplasty and 1 LASIK. Six patients underwent Confocal Microscopy. Useful data was only obtained from 5, as 1 patient had dense central corneal scarring. A significantly lower endothelial count was recorded in the affected eye (2244 ± 688 cells/mm2) compared to the fellow eye (2964 ± 505 cells/mm2). Two eyes, both with Pseudomonas infection using Lotrafilcon A on an extended wear regimen, suffered very large losses (1555 vs 3669 and 1380 vs 3127) Conclusions: Compared with daily disposable, extended wear and monthly replacement contact lenses (even high oxygen transmissibility silicone hydrogel lenses) pose a higher risk of developing microbial keratitis. Confocal Microscopy revealed that microbial keratitis produces endothelial cell loss, which can be greater in the more severe cases.
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