Contralateral effect of topical beta-adrenergic antagonists in initial one-eyed trials in the ocular hypertension treatment study

PURPOSE: To evaluate the magnitude of the contralateral effect of topically administered beta-blockers on intraocular pressure. METHODS: The Ocular Hypertension Treatment Study enrolled 1,636 subjects, O f these, 817 subjects were randomized to receive topical ocular hypotensive medication and 819 subjects were randomized to close observation (i.e,, no topical medication). We compared the intraocular pressure of the contralat eral eye of subjects at the baseline visit and after an initial one-eyed th erapeutic trial of topical beta-blockers. We examined differences between b aseline and follow-up intraocular pressure in untreated eyes of subjects ra ndomized to close observation. RESULTS: The mean reduction in intraocular pressure in the beta-blocker-tre ated eyes was -5.9 +/- 3.4 mm Hg (-22% +/- 12%; Student t rest, P < .0001). In the contralateral eyes, mean intraocular pressure reduction was -1.5 +/ - 3.0 mm Hg (-5.8% +/- 12%; P < .0001), Of the contralateral eyes, 35% show ed a reduction of 3 mm Hg or more, and 10% showed a reduction of 6 mm Hg or more. The contralateral effect of the relatively selective beta-blocker be taxolol did not differ from that of any of the nonselective beta-blockers. Factors associated with the magnitude of the contralateral effect were the degree of intraocular pressure reduction in the treated eye and baseline in traocular pressure of the contralateral eye. In the close observation group , no significant reduction in intraocular pressure was noted between the ba seline and follow-up visit. CONCLUSIONS: The contralateral effect is important in clinical practice and in clinical trials when the hypotensive effect of a topical beta-blocker i s evaluated by means of a one-eyed therapeutic trial, (C) 2000 by Elsevier Science Inc. All rights reserved.