Pupillary block during cataract surgery

Sudden phakic pupillary block occurred immediately upon cortical cleaving hydrodissection during cataract surgery in two patients. We believe this unique complication is related to the recent introduction of viscoelastics with properties that enhance the maintenance of the anterior chamber during capsulorhexis. We postulate that the cause of the block was a combination of O-ring capsulocortical and iridocapsular seals that tamponade hydrodissection fluid posteriorly. Additional precipitating factors were diabetes, poorly dilating pupils, and increased vitreous pressure, which may have contributed to the sudden and irreversible nature of this block. If this complication is not recognized, an aqueous misdirection syndrome may ensue, requiring pars plana vitrectomy. Immediate mechanical breakage of the pupillary and capsular block, resulting in an immediate decrease in intraocular pressure from greater than 70 mm Hg, may cause severe retinal vascular damage. These cases stress the importance of mechanical pupil dilation to prevent this serious complication of cataract surgery.