Purpose: Clinical differentiation of choroidal pigmented lesions is sometimes difficult. Choroidal melanoma is the most prevalent primary neoplasia among malignant ocular tumors, and metastasis often occurs before the primary tumor is diagnosed. Therefore, early detection is essential. We investigated the imaging properties of clinically diagnosed melanocytic choroidal tumors using a nonmydriatic ultra-wide-field scanning laser ophthalmoscope (SLO) with two laser wavelengths to distinguish benign from malignant lesions. Repeated standardized ultrasound (US) evaluation provided reference standard.
Methods: In a consecutive series of 49 patients with clinically diagnosed melanocytic choroidal tumors in one eye, 29 had established melanoma (defined by proven growth on repeated US follow-up) and 20 had nevi (defined by no malignancy according to clinical, US, and growth characteristics for at least 2 years). All patients underwent clinical examination, undilated Optomap((R)) (Optos PLC, Dunfermline, Fife, Scotland, UK) imaging, standardized US examination, and standard retinal photography. Measurements of the tumor base using the Optomap software were compared with US B-scan measurements. Imaging characteristics from the SLO images were correlated with the structural findings in the two patient groups.
Results: Measurements of tumor base correlated well between SLO and US with r = 0.61 (T-direction) and r = 0.51 (L-direction). On SLO imaging, typical malignant lesions appeared dark on the red laser channel and bright on the green laser channel. Based on those simple binary characteristics, a sensitivity of 76% at a specificity of 70% was obtained for a correct classification of lesions. When analogous to clinical examination lesion size, margin touching the optic disc, and existence of subretinal fluid were additionally considered, 90% sensitivity at 82% specificity was obtained.
Conclusions: In this first, limited series, nonmydriatic SLO imaging with two laser wavelengths permitted to differentiate malignant ocular tumors from nonmalignant lesions with high diagnostic accuracy. Additional parameters may further enhance diagnostic properties, but larger patient series are required to validate our findings and prove the diagnostic properties.
Keywords: choroidal melanoma; imaging; nevus; ultra-wide-field scanning laser ophthalmoscopy.