Iris cysts: A comprehensive review on diagnosis and treatment.

Iris cysts, both primary and secondary, are a diagnostic and treatment challenge. Primary cysts arise either from the iris pigment epithelium or the iris stroma. Posterior pigment epithelial cysts are subdivided according to their location as central, midzonal, and peripheral. Iris stromal cysts are classified either as congenital or acquired. Free-floating cysts are usually dislodged pigment epithelial cysts. Secondary cysts are classified according to the underlying cause as implantation cysts, drug-induced, uveitic, tumor-induced, parasitic, or as cysts associated with systemic disorders. Differential diagnosis is based on the clinical presentation and imaging. Ultrasound biomicroscopy is the gold standard for the imaging of iris cysts, combining excellent resolution with sufficient tissue penetration. Treatment of iris cysts depends largely on whether they become symptomatic or not. Symptoms include obstruction of the visual axis, corneal decompensation, secondary uveitis, and secondary glaucoma. Treatment options cover a range from simple observation to fine-needle aspiration (with or without intracystic injection of absolute alcohol or antimitotic agents), laser (argon, Nd:YAG), or surgical excision. In the past, the prevailing notion was that of a radical surgical intervention in the form of iridectomy or iridocyclectomy. Given the high rate of recurrence, a stepwise conservative approach is currently favored by most clinicians.