Enhanced depth imaging optical coherence tomography of choroidal nevus in 104 cases

Purpose: To describe the characteristics of choroidal nevus using the enhanced depth imaging (EDI) feature of spectral-domain optical coherence tomography (OCT).

Design: Retrospective, observational case series.

Participants: One hundred four eyes with choroidal nevus.

Methods: 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.

Main outcome measures: Imaging features and thickness correlation of choroidal nevus by EDI OCT versus standard ultrasonography.

Results: 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).

Conclusions: 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.