The Added Value of Enhanced Depth Imaging-Optical Coherence Tomography in the Multimodal Imaging of Choroidal Nevi

Abstract

Introduction: To analyze the enhanced depth imaging (EDI) - optical coherence tomography (OCT) ability to identify, measure and classify choroidal nevi, and its correlation with high-risk features.
Material and Methods: Retrospective observational study of patients with choroidal nevi. Comprehensive eye examinations and multimodal imaging were performed for each nevus, including spectral domain EDI-OCT and B-scan ultrasonography (US). Main outcome measures were lesion thickness and features, EDI-OCT and US findings.
Results: A total of 115 nevi (106 patients) were included. Five of the 115 nevi (4.4%) were considered suspicious lesions. Of the 114 nevi with reliable US, 83 (72.8%) were not identified, behaving as flat nevi. The mean largest basal dimension on US was 5.86 ± 2.19 mm (1.97-10.39 mm), and the mean maximal thickness was 1.37 ± 0.72 mm (0.45-2.95 mm). Sixty-two nevi had reliable EDI-OCT imaging. The mean maximum thickness on EDI-OCT was 404.93 ± 273.36 μm (139-1504 μm). The nevi maximum thickness measured in US was significantly different from the one measured by EDI-OCT (p=0.0011) for the same nevus, when both exams were reliable (US 1233.75 ± 549.57 μm; EDI-OCT 683.19 ± 343.80 μm). Thirty-eight of the 42 flat nevi on US that had an EDI-OCT performed over the lesion, were identified and measured by EDI-OCT, with a mean thickness lower than US detectability threshold. Eighteen of 62 nevi (29%) had elevation of the nevus surface and were classified as “elevated”, type 4 on EDI-OCT. EDI-OCT type was positively associated with decrease in visual acuity (p=0.014) and the presence of intraretinal fluid or sub retinal fluid (SRF) on OCT (p=0.042). All the 5 suspicious lesions were associated with high-risk features of growth or transformation, such as decrease in visual acuity, thickness greater than 2 mm, largest basal dimension greater than 5 mm and SRF.
Conclusion: EDI-OCT can consistently identify and classify nevi that are not visible on US, and enables precise thickness measurement of choroidal nevi, with reduced values compared to US.