Peripheral pigmentary iris cyst: evaluation and differential diagnosis.

Peripheral iris pigment epithelial cysts are benign lesions of the anterior segment. They are located at the iridociliary junction and can produce a localised distortion and/or displacement of the iris. Patients who have these lesions are usually asymptomatic and in the absence of a careful slitlamp examination will often remain undetected. The aetiology of these cysts is unknown and they tend to be unilateral and solitary in nature. The cyst walls are composed of iris pigment epithelium and the lumen contains clear fluid. Women are three times more likely to develop these cysts, which must be differentiated from malignancies of the iris or ciliary body. We report a case involving a peripheral pigmentary iris cyst and discuss methods of differentiating this benign lesion from serious ocular tumours.