The one-eye trial and fellow eye response to prostaglandin analogues

Background: To determine if the intraocular pressure (IOP) reduction in one-eye trial correlates with the IOP reduction in the fellow eye when IOP variability during office hours is taken into account. Methods: This retrospective observational case series includes 50 high tension (primary open-angle glaucoma, exfoliative glaucoma and ocular hypertension; Group 1) and 21 normal tension (Group 2) glaucoma patients. Charts of bilateral open-angle glaucoma patients at Glaucoma Unit, School of Medicine, Adnan Menderes University who had pretreatment baseline office IOP measurements at 9:30, 11:30 and 15:30; were put on a one-eye trial with prostaglandin analogues, and then subsequently received the same medication in the fellow eye were reviewed. Pretreatment baseline office IOP measurements and reductions in the first and second eyes were compared to determine variability and correlation, respectively. Results: Both groups showed significant variability in pretreatment baseline office IOP measurements. Peak IOP level was before noon in at least 70% of eyes in Group 1, 50% in Group 2. IOP dropped a mean of 8.8 +/- 4.8 mmHg (34%, P = < 0.0001) in Group 1 and 4.9 +/- 2.4 mmHg (30%, P = < 0.0001) in Group 2 during the one-eye trial. Following bilateral use of the medication a mean drop of 7.5 +/- 4.0 mmHg (31%, P = < 0.0001) in Group 1 and 2.9 +/- 1.9 mmHg (18%, P = < 0.0001) in Group 2 were obtained. The IOP reduction between fellow-eye pairs were significantly correlated in Group 1 (r = 0.541, P = < 0.0001) but not Group 2 (r = -0.310, P = 0.171). Conclusions: One-eye trial is a feasible method to determine the effectiveness of prostaglandin analogues and to predict the amount of IOP reduction in the fellow eye in patients with high tension glaucoma.