A Prospective, Randomized, Investigator-masked Evaluation of the Monocular Trial in Ocular Hypertension or Open,angle Glaucoma

Purpose: To evaluate the clinical value of the monocular therapeutic drug trial in predicting long-term intraocular pressure (IOP) reduction. Design: Prospective, randomized, investigator-masked trial. Participants: Twenty-six subjects with ocular hypertension or open-angle glaucoma. Methods: Subjects attended 5 study visits: 2 on no IOP-lowering therapy, 1 on monocular therapy with latanoprost, and 2 on bilateral therapy. The monocular trial eye was randomly selected, and study personnel making IOP measurements were masked to randomization. The following parameters were calculated: the unadjusted IOP change (IOP in the randomized eye at the first on-treatment visit minus IOP in the same eye at the initiation of the monocular trial); the adjusted IOP change (the unadjusted IOP change minus the comparable IOP change in the untreated fellow eye between the same 2 visits); and the long-term IOP change (the difference of the mean of the 2 on-treatment IOP values during bilateral use and the mean of the 2 pretreatment IOP values). Main Outcome Measure: The relationship between short- and long-term IOP reduction, with the coefficient of determination (the square of the Pearson correlation coefficient, r) as the measure of association. Results: The mean long-term IOP reduction after latanoprost therapy was -3.4 +/- 2.4 mmHg in first-treated eyes (P<0.0001) and -3.4 +/- 2.4 mmHg in second-treated eyes (P<0.0001). The mean unadjusted IOP reduction in the monocular trial eye was -3.1 +/- 3.4 mmHg; the correlation between the unadjusted IOP change and the long-term IOP change was weak to moderate (coefficient of determination 0.325). The mean adjusted IOP reduction was -2.8 +/- 4.3 mmHg; the correlation between the adjusted IOP change and the long-term IOP change was also weak to moderate (coefficient of determination 0.279). Conclusions: The practice of adjusting the IOP change in the treated eye by the IOP change in the untreated eye-the monocular drug trial-is no more informative than using the treated eye's unadjusted IOP change, and both of these methods are poor predictors of long-term IOP reduction with latanoprost. Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references. Ophthalmology 2009; 116:123 7-1242 (C) 2009 by the American Academy of Ophthalmology.