Abstract
Purpose::
To study if the intraocular pressure (IOP) change observed after starting a glaucoma medication in one eye is predictive of the change in IOP observed in the fellow eye once the same medication is used in both eyes.
Methods::
In a retrospective, observational study, 56 patients with bilateral glaucoma underwent monocular drug trials with various glaucoma medications before the drug was added to the second eye. The IOP change of the treated eye in monocular therapy was then compared to the IOP change of the fellow eye after binocular pharmacotherapy was initiated.
Results::
After the monocular drug trial, the IOP in the treated eye decreased 5.83 ± 6.04 mmHg (mean ± standard deviation). This represented a relative decrease of 6.26 ± 5.22 mmHg when the fellow eye was used as a control. After subsequent binocular therapy, the IOP of the second eye decreased 3.32 ± 5.62 mmHg. This represented a relative decrease of 4.23 ± 4.47 mmHg when the first eye was used as a control. The absolute IOP changes noted in the treated eye in monocular therapy and the fellow eye in binocular therapy were poorly correlated (Pearson correlation coefficient .09, p = .5). The relative IOP changes noted in monocular and binocular therapy were well correlated (Pearson correlation coefficient .40, p = 0.002).
Conclusions::
In glaucoma patients, the absolute response of one eye to a medication does not predict the future response of the fellow eye to the same medication. However, if it can be proven that the spontaneous fluctuations of pressure in fellow eyes is sufficiently symmetrical to allow one eye to serve as control when assessing the efficacy of a drug in the fellow eye, then the response of one eye to a glaucoma medication is predictive of the response of the fellow eye once the same medication is used in both eyes. Further study is needed to find the most reliable method for the monocular drug trial.
Keywords: intraocular pressure • clinical (human) or epidemiologic studies: systems/equipment/techniques • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials