Red light has the capacity to blunt corneal endothelial cell damage in situ.

Abstract

Purpose To cause damage to rat corneal endothelial cells in situ and determine whether exposure to red light blunts this influence. Methods Corneal endothelial cells from one eye in anesthetised rats were damaged by placing a needle in the anterior chamber and elevating the intraocular pressure (IOP, approximately 130mm Hg) for 60 minutes in the dark. In some instances the cornea was exposed to red light (2500 lux). Rats were either killed immediately or after periods of up to 15 days. Flat mounts and transverse sections of cornea were processed for the localisation of tight junctional protein ZO‐1 and JC‐1 to monitor mitochondrial health with their degree of depolarization indicated by changes in the red to green intensity of fluorescence. Results Raise IOP causes damage to the mosaic appearance of corneal endothelial cells clearly indicated by staining for ZO‐1. Exposure to red light during elevation of IOP reduced the amount of patchy damage to endothelial cells. Corneal endothelial cells appear green when stained with JC‐1 but after 60 minutes of raised IOP the cytoplasm of many cells appear red. Both the numbers and intensity of red endothelial cells increased in JC‐1 stained corneas exposed to red light. Three days after an insult of raised IOP, some red JC‐1 staining was present only in corneas exposed to red light. Conclusion Raised IOP causes damage and disruption of corneal endothelial cells. This process is blunted by red light. JC‐1 staining suggests that endothelial cell mitochondria are activated by raised IOP (presumably as a protective mechanism) and that this process is enhanced by red light.