Foveal photocoagulation from laser iridotomy.

Acute and permanent loss of vision has resulted from foveal photocoagulation during argon laser iridotomy. This complication can occur when the laser beam passes through the iridotomy nearly parallel to the visual axis. This is most likely to happen during enlargement of the iridotomy. A retinal burn of the macular region through a peripheral iridotomy was produced experimentally, and the mechanism of this complication is explained.