Expansion of Schlemm's Canal by Travoprost in Healthy Subjects Determined by Fourier-Domain Optical Coherence Tomography

Abstract

To determine the effect of travoprost 0.004% on Schlemm's canal (SC) in healthy human eyes using Fourier-domain optical coherence tomography (FD-OCT). Twelve healthy volunteers were recruited for a double-blind, placebo-controlled, randomized, and paired comparison study. Right eyes of subjects were randomly assigned to receive either travoprost 0.004% or placebo; the contralateral eye received the other treatment. FD-OCT imaging of SC and measurements of IOP were carried out before and at 1, 2, 4, 6, 8, 12, 24, 36, 48, 60, 72, and 84 hours after eye drop instillation. After instillation of travoprost eye drops, IOP gradually reduced, and the SC lumens expanded, while those values remained unchanged in placebo treated eyes. At 8 hours after the travoprost administration, the mean SC area increased 90.30% and 90.20%, respectively, in the nasal and temporal quadrant of the treated eyes as compared with the placebo group. The SC area and IOP showed a similar pattern of changes at most time points examined. In travoprost-treated eyes, a statistically significant correlation between SC area and IOP is observed (r = -0.2817; P = 0.0004). Measurements of the SC area showed sufficient repeatability and reproducibility. SC can be noninvasively imaged and quantitatively assessed in the living healthy human eye by FD-OCT. Travoprost treatment leads to SC lumen expansion accompanied by a drop of IOP in the healthy eye, likely as a result of the enhancement of pressure sensitive trabecular meshwork outflow induced by travoprost.