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Editors Selection IGR 8-1
Medical treatment: Lens opacifications
Comment by Cristina Leske on:
15248 Topical ocular hypotensive medication and lens opacification: evidence from the ocular hypertension treatment study, Herman DC; Gordon MO; Beiser JA et al., American Journal of Ophthalmology, 2006; 142: 800-810
Do topical hypotensive medications cause lens opacities? After four years of follow-up, the Barbados Eye Studies reported a three-fold risk of nuclear lens opacities in users of topical hypotensive medications. Additionally, in the Early Manifest Glaucoma Trial, patients randomized to betaxolol and argon laser trabeculoplasty developed significantly more nuclear opacities than untreated controls. And the Blue Mountains Eye Study found an increased five-year incidence of nuclear cataract among ocular hypertensives, with a non-significant odds ratio of 1.9 for medication users.
To investigate this question, Herman et al. (1217) compared OHTS-treated vs. control groups regarding the frequency of cataract surgery and of lens opacities, using LOCS III slit-lamp gradings. The OHTS-treated patients had significantly more cataract extraction and cataract/filtering surgery than controls
The OHTS-treated patients had significantly more cataract extraction and cataract/filtering surgery than controls (7.6% vs. 5.6%; Hazard Ratio = 1.56; 95% confidence interval: 1.05-2.29), which was not explained by the possible confounders investigated. The treated group also tended to have increased posterior subcapsular LOCS III scores (p = 0.07). As in the earlier studies, cortical scores were unrelated to treatment, but OHTS results differ in that nuclear scores were similar in treated and control groups. Refractive changes, visual symptoms and visual function were also comparable in comprehensive analyses.
The higher surgical rates in the OHTS-treated group support an effect of topical medications, with approximately a 56% estimated increase in surgery risk. The LOCS III data are difficult to interpret because gradings were performed once, and after control patients had already received treatment (median = 1.2 years (range: 0-8.6 years) vs. 8.5 years (range: 0-10.2 years) in the treated group.) The results are thus based on cross-sectional analyses comparing patients with shorter vs. longer duration of treatment. In contrast, the other studies were prospective, with at least four years of follow-up; they also used different grading systems and their participants were older. These features could have obscured any potential effects of treatment, as the authors discuss. Evidence from additional prospective studies is needed to further quantify potential cataractogenic effects of these medications.
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