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.
West Virginia University Eye Institute, Morgantown, West Virginia
Correspondence: Tony Realini, MD, West Virginia University, 1 Stadium Drive, Morgantown, WV 26505
Manuscript no. 2008-1173.
Financial Disclosure(s): The author has received research support from Alcon, Merck, and Pfizer; is a consultant for Alcon; and is a member of the speakers' bureau for Alcon, Merck, and Pfizer.
Supported by a research grant from Pfizer Inc. Pfizer personnel were not involved in the design, implementation, analysis, or manuscript preparation for this study.
ABSTRACT