Late closure of argon laser iridotomies following regrowth of iris pigment epithelium.

Closure of previously patent laser iridotomies has been described as occurring early or late after the procedure. Early closure, occurring from minutes to hours after completion of the iridotomy, results from landsliding of iris pigment epithelium from above the site of the iridotomy or from large pigment particles floating in the posterior chamber, lodging in the iridotomy site, and occluding it. Late closure may occur due to occlusion by the settling of dispersed pigment and/or inflammatory debris into a small iridotomy and/or proliferation of pigment with bridging of the iridotomy and usually occurs after days to weeks. In most cases, this pigment appears to come from the stroma, and the pigment plugging of the iridotomy is anatomically at the level of the iris stroma. Iris pigment epithelial proliferation has been considered extremely rare and to our knowledge has not been previously described after laser iridotomy. Closure of iridotomies by proliferation of iris pigment epithelium has been alluded to in various reports, but published photographs indicate pigment proliferation plugging the iridotomy at the level of the stroma, not at the level of the iris pigment epithelium. We present 2 cases in which true regrowth of the iris pigment epithelium solely at the appropriate anatomic level resulted in recurrence of pupillary block.