A study of the mechanism of ocular irritation following YAG laser capsulotomy in rabbits.

The irritative response to Nd:YAG laser capsulotomy was studied in unanaesthetized rabbits. Posterior lens capsulotomy with a total energy of 100 mJ had no effect on the pupil size but increased the intraocular pressure by 5-10 mmHg and caused a breakdown of the blood-aqueous barrier. Anterior lens capsulotomy with a total energy of 20, 60 or 100 mJ caused constriction of the pupil, and an increase in intraocular pressure in a dose-dependent manner, and a breakdown of the blood-aqueous barrier. Indomethacin attenuated all the component parts of the irritative response and (D-arg1, D-pro2, D-trp7,9, leu11)-SP attenuated the miotic response. A combination of indomethacin and the substance P antagonist almost completely abolished the irritative response. This indicates that the acute YAG-laser-induced irritation in the rabbit eye is dependent both on a release of prostaglandins and on substance P, the former probably releasing the latter from sensory nerves.