Optical coherence tomographic correlates of angiographic subtypes of occult choroidal neovascularization

To compare the optical coherence tomographic (OCT) correlates of two previously described angiographic subtypes of occult choroidal neovascularization (CNV).

We retrospectively analyzed 17 consecutive patients with previously untreated occult CNV who underwent both fluorescein angiography (FA) and volume spectral domain (SD)-OCT imaging on the same visit. Planimetric grading was performed on the FA images by certified reading center graders to precisely outline the boundaries of the fibrovascular pigment epithelial detachment (FVPED) and/or late leakage of undetermined source (LLUS) components of occult CNV for each case. In the SD-OCT images, the outer retinal pigment epithelial (RPE) and inner choroidal boundaries were manually segmented on all B-scans to generate a PED thickness map. Fluorescein angiography images were manually registered with the OCT fundus image, and the PED thickness was correlated with the angiographic lesion component present at each corresponding point in the fundus.

Point-to-point correlations revealed that PED thickness was significantly different in areas of FVPED versus areas of LLUS. Whereas the mean PED thickness in areas of FVPED was 196.1 ± 120.36 μm, it was only 38.42 ± 8.14 μm in areas of LLUS (P = 0.003). Normalized internal reflectivity in areas of FVPED was lower than in areas of LLUS (0.12 ± 0.11 vs. 0.24 ± 0.07; P = 0.03). The integrity or continuity of the overlying RPE band on OCT, however, did not appear to differ between areas of LLUS and FVPED (P = 0.33).

Although LLUS and FVPED appear to be distinct angiographic subtypes of CNV, the major difference between the two is the height of the RPE elevation and the internal reflectivity, with areas of LLUS representing much shallower RPE elevations with brighter mean internal reflectivity.