Time Course of Conjunctival Hyperemia Induced by a Rho-kinase Inhibitor Anti-glaucoma Eye Drop: Ripasudil 0.4%

Purpose: We investigated the detailed time course of conjunctival hyperemia induced by ripasudil 0.4%, a novel Rho-kinase inhibitor anti-glaucoma eye drop, in healthy subjects. Methods: We recruited 51 healthy subjects and administered ripasudil 0.4% in their right eye. We evaluated conjunctival hyperemia using slit lamp photography and measured the intraocular pressure (IOP) using the Icare PRO Rebound Tonometer at baseline and after 5, 15, 30, 60, 90, and 120 min. The conjunctival hyperemia score was graded by three independent observers on a scale of 0 (none) to 3 (severe). Additionally, we analyzed the percent coverage of conjunctival hyperemia by using an automated hyperemia analysis software program; this program provides the pixel coverage of the conjunctival vessels in the region of interest. Dunnett and Steel multiple comparison tests were used, as appropriate, for the subsequent analyses. Results: The conjunctival hyperemia score and percent coverage increased rapidly after the instillation of ripasudil 0.4%, peaking at 15 min (score: 1.83 0.29 [mean +/- SD]) and 5 min (11.6% +/- 4.7%), respectively, and then gradually decreasing until 120 min (0.45 +/- 0.22 and 4.7% +/- 1.8%, respectively), when they reached a level that was not significantly different from the baseline values. The IOP decreased significantly compared to the baseline at 30, 60, and 90 min, based on the Dunnett test. Conclusion: Conjunctival hyperemia induced by ripasudil 0.4% peaks rapidly to moderate severity, but subsides relatively quickly.