Choroidal pigmented lesions imaged by ultra-wide-field scanning laser ophthalmoscopy with two laser wavelengths (Optomap)

Abstract

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.

Figure 1

Base diameters of lesions measured in US and Optomap. A) T-direction and B) L-direction.

Figure 2

A) Optomap composite image showing the typical appearance of an untreated choroidal melanoma (red and green channel superimposed). B) Detail of the fundus image from Figure 2A, as viewed with the specific Optomap viewing software (composite image on the left, red and green separation on the right). The lesion appears dark in the red channel and bright in green channel. C) Red separation image (untreated melanoma). D) Green separation image (untreated melanoma).

Figure 3

A) Optomap composite image showing the typical appearance of a choroidal nevus (red and green channel superimposed). Due to the nonconfocal SLO imaging, some bright spots anterior to the lesion are imaged and some lashes in the upper part of the image also appear in focus. B) Detail of the according fundus image from Figure 3A, as viewed with the specific Optomap viewing software (composite image on the left, red and green separation on the right). The lesion appears dark in the red channel and dark in green channel. Due to the nonconfocal SLO imaging, some bright spots anterior to the lesion. C) Red separation image (nevus). D) Green separation image (nevus).

Figure 4

A) Optomap composite image showing the typical appearance of a choroidal melanoma after radiation therapy (red and green channel superimposed). B) Detail of the according fundus image from Figure 4A, as viewed with the specific Optomap viewing software (composite image on the left, red and green separation on the right). The lesion appears bright in the red channel and bright in green channel. C) Red separation image (treated melanoma). D) Green separation image (treated melanoma).