Experimental Evaluation of Travoprost-Induced Changes in Biomechanical Behavior of Ex-Vivo Rabbit Corneas

Purpose: To assess the effects of prostaglandin F2α analogues travoprost on the biomechanical behavior of ex-vivo rabbit cornea. Materials and Methods: 18 Japanese white rabbits were included in the study. The left eye (treated group, Tr) of each rabbit was preserved for 10 days in storage medium Eusol-C solution with 1:10 travoprost diluent, while the contralateral eye (control group, Co) was preserved in a similar but travoprost-free medium. Strips of corneal tissue were dissected and tested under cyclic load conditions with up to 0.1 N uniaxial tension force. The resulting load-elongation data were used to derive the stress-strain behavior and the tangent modulus (Et) of the tissue. Differences in Et between the treated (Et-_Tr) and control group (Et-_Co) were assessed statistically to determine the biomechanical effects of travoprost on the cornea. Results: Central corneal thickness (CCT) in the two groups was similar before (P = 0.073) and remained similar after storage (P = 0.303) although it became significantly thicker in both groups after preservation (P < 0.01). Compared with the control group, the travoprost treated corneas exhibited lower Et values but the differences reduced and became insignificant with rises in stress to which the tissue was subjected (1 - Et-_Tr/Et-_Co = -11.7 ± 41.8%, P < 0.05 at 10 kPa stress; -9.2 ± 36.1%, P > 0.05 at 20 kPa; -7.3 ± 35.4%, P > 0.05 at 30 kPa). Conclusions: Significant reductions in corneal stiffness, that are associated with the use of travoprost, were observed experimentally under low applied stresses. This stiffness-reduction effect should be considered in clinical management, especially in primary open angle glaucoma treatment.