Evaluation of iris and iridociliary body lesions with anterior segment optical coherence tomography versus ultrasound B-scan

AIMS: To compare anterior segment optical coherence tomography (AS-OCT) with ultrasound B-scan (USB) in evaluating iris and iridociliary body lesions. METHODS: Image features and resolution comparison between AS-OCT and USB in 126 patients (126 eyes) presenting with iris or iridociliary body lesion. Bland–Altman plots were generated to assess the level of agreement between the two techniques. RESULTS: The three most common diagnoses were iris naevi (62 (49.2%)), iris pigment epithelial cysts (23 (18.3%)) and iris melanoma (11 (8.7%)). Image feature comparison for USB was better than AS-OCT in visualising all tumour margins (81 (64.3%) vs 59 (46.8%)), posterior tumour margin (54 (42.9%) vs 16 (12.7%)) and producing less posterior shadowing (121 (96%) vs 43 (34.1%)). Image resolution comparison revealed USB to be slightly better for resolving the overall tumour (45 (35.7%) vs 43 (34.1%)) and posterior tumour surface (70 (55.6%) vs 32 (25.4%)) but AS-OCT was better for resolving the anterior (62 (49.2%) vs 4 (3.2%)) and lateral tumour surface (62 (49.2%) vs 31 (24.6%)). Comparing the three most common diagnoses, USB was better for visualising iris pigment epithelial cysts (12 (52.2%) vs 2 (8.7%)) and iris melanoma (7 (63.6%) vs 1 (9.1%)) but AS-OCT was better (28 (45.2%) vs 15 (24.2%)) for visualising iris naevi. Bland–Altman plots showed good agreement between the two techniques for lesions smaller than 3 mm in base and 2 mm in elevation. CONCLUSIONS: AS-OCT is superior to USB for imaging small lesions pertaining to the anterior iris but USB is better for imaging larger iris lesions with posterior or ciliary body extension.