Wound healing by the rat lens after neodymium-YAG laser injury

Wound healing of the ocular lens after exposure to neodymium-YAG laser energy (3.9-4.2 mJ) was studied. Male Sprague-Dawley rats were killed 5 min and 5, 9 and 15 days after the anterior lens epithelium was injured by a laser pulse. Gross and biomicroscopic examination revealed that a white, opaque mass formed on the lens surface after about 30 min. Five days later, the opacified mass present on the lens surface was found to be composed of ectopic epithelial cells, protruding lens fibers and a variety of other cell types. Epithelial cells were also present in abundance on the capsule surface in the immediate vicinity of the wound. Deep to the capsule, the lens fibers were greatly swollen. Half of the epithelial mounts obtained 5 days after surgery showed disorganization of the epithelium at points distant from the eosinophilic scar. The opacified external mass had disappeared from all of the lenses obtained at the 15-day period. However, the scar was readily identifiable in epithelial whole mounts, methacrylate sections and SEM specimens obtained from lenses at this time period. At every time period, many cortical fibers were swollen although the amount of swelling was less at 15 days than at earlier periods. The changes observed are similar to the lenticular alterations that occur after experimentally induced, transcorneal mechanical injury of the lens.