Experimental iridotomy with the Q-switched neodymium-YAG laser.

Iridotomies were performed on pigmented rabbits with a Q-switched ophthalmic neodymium-YAG (Nd-YAG) laser and an argon laser. Because short-pulsed Nd-YAG lasers are effective in performing capsulotomies of the crystalline lens, injury to the underlying lens was evaluated by slit-lamp biomicroscopy at various intervals following the iridotomy, and then lenses were examined in vitro with the use of procion yellow, an extracellular dye. Patent iridotomies were produced with one to two pulse applications of the Nd-YAG laser. Focal areas of pigment deposition on the lens capsule and focal lens capsule opacities underlying the iridotomy site were observed, but no inadvertent capsulotomies occurred. Lens injury could be minimized through optimal focusing and energy selection. Minimal hemorrhage occurred with Nd-YAG laser iridotomy; prior treatment with the argon laser was not necessary to achieve hemostasis.