OCT classification of choroidal nevi

Choroidal nevi (CN) are commonly divided into non-suspicious (stable) and suscpicious (progressive). However, there are still no clear data on OCT patterns of nevi progression, their transformation into initial melanomas. Purpose. The study aims to determine the types of OCT patterns of CN and to evaluate their prognostic value. Material and methods. The study included 50 patients with CN (53 nevi). The height of 19 nevi evaluated with ultrasonography was 1.33±0.43 mm, diameter — 5.47±1.68 mm. Results. CN is an area of local increase in reflectivity of the choroid; its widening and elevation of the tomographic section were observed in 72% of nevi. In more than half of all cases a distinct hyperreflective border was revealed between the CN and adjacent choroid. In two thirds of all cases the choriocapillaris layer was preserved and visualized mainly along the edge of lesion. Analysis of OCT scans showed distinct differences, which allowed designation of four OCT types of CN: 1) nevi with typical OCT pattern; 2) nevi with changes in retinal pigment epithelium (RPE); 3) nevi with neuroepithelial detachment; 4) nevi with atypical OCT pattern. Conclusion. Based on the analysis of OCT images of the determined types of nevi, it can be assumed that all of them initially had typical OCT pattern. With enlargement of the nevi and increase in the duration of its presence in the choroid, dystrophic processes in the adjacent retina and changes in RPE begin to occur. Disturbed pumping ability of the damaged RPE results in disruption of the trophism of adjacent retina, which leads to development of atrophic changes. Nevi with atypical OCT pattern should be considered as a sign of long-term benign process in the choroid that will cause atrophic changes in the choroid and adjacent retina, while nevi with changes in RPE and with neuroepithelial detachment — as a risk factor for transition to choroidal melanoma.