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This paper by Kanthan et al. (1213) from the Blue Mountains Eye Study, reports a significant association between the use of beta blockers (taken orally and/ or topically) and the incidence of cataract surgery over a ten-year period. This association was also found in those on angiotensin-converting enzyme (ACE) inhibitors but not those on diuretics.
Strengths of this analysis include the fact that this was a population-based rather than clinic-based study and that there were relatively large numbers of subjects in the 'affected' and 'at risk' groups after such a long period of followup. The authors adjusted for factors known to influence cataract formation and cataract surgery that included age, gender, blood pressure, smoking, diabetes, myopia, socio-economic status and steroid use. None of the different classes of oral antihypertensive agents were significantly (P < 0.05) associated with the development of any subtype of cataract after the baseline examination. It is probable that those on topical beta blockers (n = 43) would be significantly more likely to undergo cataract surgery as they will be under regular follow-up for glaucoma/ocular hypertension and hence more likely to be offered cataract surgery than those subjects not on such treatment (detection bias). Observation of a surge in cataract operations shortly after the follow up assessments or data supporting increased numbers of hospital/eye care visits among those who went on to have cataract surgery might have lent support to this argument. The finding of a three-fold increased risk of nuclear cataract in those on topical beta-blockers is interesting and highlights the need for more understanding of this topic. Topical medication is usually considered the 'conservative' approach to glaucoma management, however it is clearly not without its problems.