Effect of Unoprostone on Topographic and Blood Flow Changes in the Ischemic Optic Nerve Head of Rabbits

Objective To determine whether subconjunctival injection of unoprostone isopropyl alters changes in the topography and blood flow of the optic disc induced by endothelin 1 (ET-1) in rabbits. Methods From April 1, 2005, to April 28, 2006, we injected ET-1 (20 pmol) intravitreally into rabbits twice per week for 4 weeks. The observation period was 8 weeks. The first group received an intravitreal injection of ET-1 followed by a subconjunctival injection of unoprostone (0.12%, 50 μL). The second group received the same amount of ET-1 followed by a subconjunctival injection of the vehicle of unoprostone. The third group received the intravitreal vehicle of ET-1. The blood flow and topography of the optic nerve head (ONH) were measured by laser speckle flowgraphy and confocal scanning ophthalmoscopy, respectively. The number of cells in the retinal ganglion cell layer and inner nuclear layer was determined histologically. Results We found that ET-1 decreased the ONH blood flow, decreased the cells in the ganglion cell layer and inner nuclear layer, enlarged the cup area of the ONH, and reduced the rim area of the ONH. When unoprostone was given with ET-1, no such changes occurred. Conclusion Unoprostone can suppress the effects of ET-1 on the circulation and topography of the ONH. Clinical Relevance Unoprostone could be a candidate for treating eyes with ischemic ONH.