A 61-year-old male on evaluation for cataracts had visual acuity of 20/80 in the right eye and 20/25 left eye. The left eye was normal. In the right eye, a smooth surfaced dark brown lesion could be seen behind the iris from 4 to 5.30 O′clock position with thinning of iris stroma anteriorly and a sectoral cataract posteriorly (Figure 1a). Gonioscopically, anterior bowing of the iris and posterior indentation of the lens was observed (Figure 1b). Anterior segment ultrasound biomicroscopy revealed a circumscribed solid mass in the angle region with posterior tilting of the inferior pole of the lens (Figure 2a). The lesion appeared to arise from the posterior aspect of the iris with sparing of the iris stroma (Figure 2b). Adenoma of the iris pigment epithelium was suspected and confirmed histopathologically after removal by iridocyclectomy (Figure 3a). The cataract progressed over the next 3 months. Phacoemulsification cataract surgery with capsular bag placement of intraocular lens was performed. In addition, a blue coloured Oculaid® iris prosthesis (Ophtec Inc., Boca Raton, USA) was placed in the capsular bag to mask the surgical coloboma. At 4 weeks postoperatively, the uncorrected visual acuity was 20/25 and patient had no visual complaints (Figure 3b).

Figure 1
figure 1

(a) Anterior segment photograph of the right eye. Note a dark brown lesion visible inside the pupillary margin from 4 to 5.30 O′ clock position with thinning of iris stroma anteriorly and a sectoral cataract posteriorly. (b) Goniophotograph showing anterior bowing of the iris due to posterior chamber mass (*).

Figure 2
figure 2

(a) Anterior segment ultrasound biomicroscopy (20 MHz) revealed a circumscribed solid mass in the angle region tilting the inferior pole of the lens. (b) The lesion appeared to arise from the posterior aspect of the iris (arrows) with sparing of the iris stroma.

Figure 3
figure 3

(a) Photomicrograph showing tumour consisting of pigment-containing polygonal cells arranged in tubule like groups with vascularised connective tissue septae, and prominent basement membrane (Hematoxylin and Eosin, original magnification × 6.6). (b) At 4 weeks following phacoemulsification cataract surgery with capsular bag placement of iris prosthesis to mask the surgical coloboma.

Adenoma of the iris pigment epithelium is a rare benign tumour which usually appears as a solid dark coloured mass arising from the posterior aspect of the iris with sparing of the iris stroma.1, 2 Iris pigment epithelial adenoma should be differentiated from iris melanoma.3, 4 In symptomatic cases, adenoma can be excised. Surgical coloboma can be corrected by iridoplasty, painted contact lens, or by capsular bag placement of iris prosthesis at the time of cataract surgery.5