Safety and efficacy of intracapsular tranilast microspheres in experimental posterior capsule opacification

Purpose To evaluate the safety and efficacy of a sustained-release agent designed to reduce posterior capsule opacification (PCO). Setting Department of Ophthalmology, EENT Hospital, Fudan University, Shanghai, Peoples Republic of China. Methods Free tranilast (T Free ) was incorporated into polylactic acid microspheres and then tested using a rabbit model of PCO. Twenty-nine rabbits were randomized into 5 groups treated with balanced saline solution (BSS control); T Free ; or 0.5, 1.0, or 2.0 mg tranilast microspheres (T Micro ). Standard phacoemulsification cataract surgery, including manual aspiration of all visible soft lens matter, was performed in all groups. The selected test agent was then injected into the lens capsule. Postoperative clinical examinations were performed at 1, 3, 7, 14, 30, 60, and 90 days. Posterior capsule opacification was quantified using high-resolution computer image analysis at 1, 2, and 3 months. Histological examination was performed at 3 months. Results Eyes treated with T Micro had significantly less PCO than the eyes in the BSS and T Free groups. While the BSS control eyes had increased PCO over 3 months, eyes in the T Micro group had reduced PCO over time in a dose-dependent fashion. Histological examination showed reduced lens epithelial cell proliferation in the T Micro groups, with no manifest damage to the cornea, iris, or retina compared with the BSS controls. There was a transient increase in postoperative inflammation in all tranilast-treated groups compared with the BSS controls. Conclusion Sustained-release intracapsular tranilast reduced PCO in an experimental model of PCO, suggesting further investigation of its therapeutic potential is justified.