Enhanced Depth Imaging Optical Coherence Tomography of Choroidal Nevus in 104 Cases

Abstract

To describe the characteristics of choroidal nevus using the enhanced depth imaging (EDI) feature of spectral-domain optical coherence tomography (OCT). Retrospective, observational case series. One hundred four eyes with choroidal nevus. Spectral-domain EDI OCT was performed with a Heidelberg Spectralis HRA+OCT (Heidelberg Engineering, Heidelberg, Germany) using a custom scan acquisition protocol of up to 13 raster lines of 9-mm scan length with automatic real-time image averaging set at 100 images. The thickness of choroidal nevus was measured by combining Heidelberg's autosegmentation with manual segmentation. Imaging features and thickness correlation of choroidal nevus by EDI OCT versus standard ultrasonography. Of 104 eyes with choroidal nevus imaged with EDI OCT, 51 (49%) displayed image detail suitable for study. The remaining 53 cases were suboptimal because of statistically identified factors of age older than 60 years (P = 0.027), female gender (P = 0.008), extramacular location of nevus (P<0.001), mean distance from foveola more than 3 mm (P = 0.002), mean distance from optic disc more than 4 mm (P<0.001), and mean maximal basal diameter more than 5 mm (P = 0.006). Of the 51 suitable cases, mean nevus thickness was 685 μm (median, 628 μm; range, 184-1643 μm) by EDI OCT compared with 1500 μm (median, 1500 μm; range, 1000-2700 μm) by ultrasonography. The most common EDI OCT imaging features included partial (59%) or complete (35%) choroidal shadowing deep to the nevus, choriocapillaris thinning overlying the nevus (94%), retinal pigment epithelial (RPE) atrophy (43%), RPE loss (14%), RPE nodularity (8%), photoreceptor loss (43%), inner segment-outer segment junction (IS-OS) irregularity (37%), IS-OS loss (6%), external limiting membrane irregularity (18%), outer nuclear and outer plexiform layer irregularity (8%), and inner nuclear layer irregularity (6%). Overlying subretinal fluid was identified by EDI OCT (16%), ophthalmoscopic examination (8%), and ultrasonographic evaluation (0%). A comparison of pigmented versus nonpigmented nevus showed only 1 significant difference of more intense choroidal shadowing with pigmented nevus (P = 0.046). Imaging of choroidal nevus with EDI OCT enables precise measurement of tumor thickness with comparatively reduced thickness relative to ultrasonography. Using EDI OCT, 94% of choroidal nevi were found to have overlying choriocapillaris thinning.