The effect of neodymium: YAG laser capsulotomy on aqueous humor dynamics in the monkey eye.

The creation of a posterior capsulotomy utilizing a neodymium:YAG (Nd:YAG) laser is often followed by an increase in the intraocular pressure (IOP). In order to study the cause of this pressure rise, six eyes of three cynomolgus monkeys underwent extracapsular cataract extraction followed 2 to 3 months later by Nd:YAG laser capsulotomy. Eyes were evaluated clinically and examined histopathologically at 1 hour, 3 hours, 1 day, 3 days, 1 week, and 1 month after laser treatment. Although IOP did not increase after laser capsulotomy, outflow facility was decreased 80% from baseline levels at 3 hours, at 3 hours, 1 day, and 3 days. After laser treatment, the anterior chamber and meshwork contained fibrin, lens material, inflammatory cells, pigmented macrophages, erythrocytes, and free pigment. Most of these elements had cleared the meshwork by 1 month.