Purpose
To develop a method of visualizing reduced choriocapillaris density using optical coherence tomography (OCT) angiography.
Methods
Macular scans of a participant with a clinical diagnosis of choroideremia were taken using a spectral OCT system (RTVue-XR) and compared with normal participants. The split-spectrum amplitude-decorrelation angiography algorithm was used to detect flow. The inner retinal layer from the internal limiting membrane to 90 µm below showed the retinal circulation. The choriocapillaris layer was defined to be 10 µm below Bruch’s membrane to 20 µm below. Flow projections from retinal vessels were treated as null in the choriocapillaris layer. The choriocapillaris angiogram was then split into 8x8 superpixels, and the vessel density was calculated for each superpixel. This vessel density map was then smoothed using linear interpolation.
Results
In the choroideremia case, en face OCT angiogram of the retinal circulation appeared normal (Fig. 1A). The en face structural OCT of the retinal pigment epithelium (RPE) showed hyporeflective regions indicating RPE loss (Fig. 1B). The choriocapillaris angiogram and vessel density map showed distinct areas of reduced flow (Fig. 1C-E). Overlay (Fig. 1F) showed patches of reduced choriocapillaris vessel density within regions of RPE loss.
Conclusions
We have developed a method to visualize reduced choriocapillaris density. This method may be useful in the assessment of diseases such as choroideremia and age-related macular degeneration.