Echographic evaluation of primary cysts of the iris pigment epithelium

Primary cysts of the iris pigment epithelium frequently appear to be focal elevations of the peripheral iris. To differentiate them from other anterior segment tumors requires the ability to assess the distribution, tissue characteristics, and progression of such lesions, which we accomplished by using anterior segment echography.

We reviewed the medical records of 49 consecutive patients referred to the Doheny Eye Institute for echographic evaluation of focal bulging of the peripheral iris. Echography of the anterior segment was performed on each patient by using an immersion technique. Clinical examination was also performed on 20 (41%) patients at the time of initial examination.

We identified 52 iris pigment epithelial cysts in 52 eyes of the 49 patients studied. All lesions were single, localized to the posterior iris surface, and demonstrated a well-circumscribed, echolucent structure on B-scan echography. Average maximal sagittal thickness was 1.6 +/- 0.4 mm. Cysts were most frequently located in the inferotemporal quadrant (31%). Minimal increase in size or regression of lesions was noted in the nine patients (ten eyes) for whom follow-up echographic examinations were available.

Primary iris pigment epithelial cysts possess characteristic features with regard to location, size, and internal structure, which can be accurately documented with echography. Clinically evident lesions tend to be between 1 and 4 mm in maximum sagittal thickness, conform to the contour of posterior chamber structures without distortion, produce anterior bulging of the peripheral iris, are preferentially located in the inferotemporal quadrant, and demonstrate limited potential for growth.