Asymmetry of Effect of Latanoprost on Right versus Left Intraocular Pressures Over 24 Hours in Glaucoma Patients

Abstract

Purpose: : To assess the asymmetry of right versus left intraocular pressure (IOP) responses to latanoprost in the eyes of open angle glaucoma patients.

Methods: : Eighteen subjects (ages 41–77 years) with untreated open angle glaucoma were included. Subjects were housed in a sleep laboratory for 24 hours and a baseline IOP profile was created. IOP of both eyes was measured with a pneumatonometer every two hours in the sitting and supine positions from 7AM to 11PM, and in the supine position only from 11PM to 7AM. Subjects then initiated treatment with latanoprost 0.005% ophthalmic solution instilled in both eyes at bedtime. After at least four weeks of treatment, subjects were then housed in the sleep laboratory for a second 24 hour period during which IOP was measured again. The mean change in IOP in response to latanoprost was then compared between right and left eyes during office hour (9:30AM to 3:30PM), diurnal, nocturnal, and 24 hour periods. The strength of association between right and left eye IOP prior to initiation of therapy and IOP responses to treatment were evaluated using coefficients of determination (R²).

Results: : The mean difference between right and left eye IOP responses in the habitual body positions to treatment with latanoprost was 0.61 mmHg ± 2.38 during the office hour period, 0.37 mmHg ± 2.28 during the diurnal period, 0.92 mmHg ± 2.14 during the nocturnal period and 0.55 mmHg ± 1.83 during the entire 24 hour period. The strength of association between right and left eye 24–hour habitual IOP prior to initiation of therapy was moderate when evaluated across the 24 hour period (R² = 0.579). The strength of association between mean right and left eye responses to latanoprost treatment averaged across the 24 hour period in habitual body positions was even weaker (R² = 0.413). The association between right and left eye responses to latanoprost treatment was especially weak during the office hour period in the sitting position (R² = 0.274).

Conclusions: : In this group of open angle glaucoma patients, the strength of association between right and left IOP responses to treatment with latanoprost was weak to moderate. This suggests that a monocular therapeutic trial may not necessarily predict the response of the fellow eye to topical latanoprost therapy.

Keywords: intraocular pressure • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials • circadian rhythms