Kamal, Deborah Soraya; (2001) The conversion of ocular hypertension to early glaucoma: Epidemiology, risk factors, early detection and treatment. Doctoral thesis (M.D), UCL (University College London).

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Abstract

Background: The management of ocular hypertension (OHT) has considerable practical and financial implications for ophthalmology services in the U.K. Previous prophylactic treatment trials for OHT have so far been inconclusive (Kass, 1980, Epstein, 1989, Schulzer, 1991). New methods of detecting early glaucomatous damage are needed to identify ocular hypertensive patients at greatest risk of developing glaucoma, so that appropriate treatment may be targeted at those individuals. Objectives 1. To determine the effect of betaxolol on the conversion rate of OHT to early glaucoma. 2. To identify possible risk factors for conversion. 3. To evaluate methods of early detection of glaucoma, as compared to gold-standard methods. Methods: 356 ocular hypertensives were randomised to treatment with betaxolol drops or placebo, and followed 4 monthly for 2-6 years with visual field testing, intra-ocular pressure (IOP) measurement and optic disc and retinal nerve fibre layer (RNFL) imaging. Conversion was defined using visual field criteria. Results: 1. No overall protective effect of betaxolol against conversion was found as compared to placebo. 2. The converters had significantly higher pre-and post-treatment IOPs than the group of non-converters. Betaxolol had a smaller hypotensive effect on the mean pre-treatment IOP level of the converters. 3. Sequential HRT analysis demonstrated glaucomatous optic disc change, prior to reproducible visual field change in the converters. Some non-converters demonstrated optic disc change despite maintaining normal visual fields. Conclusions: Betaxolol did not affect the conversion rate as compared to placebo, despite having a statistically significant IOP lowering effect. Higher IOP levels are a risk factor for conversion. Betaxolol appeared to have a smaller hypotensive effect in the converting group, and it is possible that these less responsive patients are therefore at greater risk of conversion. The HRT is a useful tool for the early detection of glaucomatous optic disc damage and may identify patients at risk of developing visual field loss.

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