Clinical Applications of Optical Coherence Tomography Angiography in Inherited Retinal Diseases: An Up-to-Date Review of the Literature

Abstract

Optical coherence tomography angiography (OCT-A) is a valuable imaging technique, allowing non-invasive, depth-resolved, motion-contrast, high-resolution images of both retinal and choroidal vascular networks. The imaging capabilities of OCT-A have enhanced our understanding of the retinal and choroidal alterations that occur in inherited retinal diseases (IRDs), a group of clinically and genetically heterogeneous disorders that may be complicated by several vascular conditions requiring a prompt diagnosis. In this review, we aimed to comprehensively summarize all clinical applications of OCT-A in the diagnosis and management of IRDs, highlighting significant vascular findings on retinitis pigmentosa, Stargardt disease, choroideremia, Best disease and other less common forms of retinal dystrophies. All advantages and limitations of this novel imaging modality will be also discussed.

Keywords: Best disease; Stargardt disease; choroideremia; inherited retinal diseases; optical coherence tomography angiography; retinitis pigmentosa.

Figure 1

Multimodal imaging features in a patient with genetically confirmed retinitis pigmentosa. (A) Color fundus image displays pallor of the optic disc, attenuation of retinal vessels, extensive retinal atrophy, and pigmentary clumping in mid-periphery. (B) Blue-light autofluorescence (BAF) shows a granular hypoautofluorescence extending from the perifoveal region to the midperiphery. En face 6 × 6 optical coherence tomography angiography with corresponding B scan angio flow of superficial capillary plexus (C), deep capillary plexus (D), and choriocapillaris (E) with automatic segmentation. Flow voids areas are denoted in all retinal plexuses, and especially in the choriocapillaris, possibly related to either segmentation artifacts, outer retinal atrophy, or extremely reduced blood flow which fails to produce a signal (see corresponding B scans angio flow).

Figure 2

Multimodal imaging evaluation in a patient with genetically confirmed choroideremia. (A) Color fundus photograph shows extensive retinal degeneration with chorioretinal atrophy. (B) Blue light fundus autofluorescence shows typical patterns of a sharply demarcated macular area of remaining tissue (hyper/iso-autofluorescent) against surrounding atrophic RPE (hypoautofluorescent background). (C) En face 6 × 6 optical coherence tomography angiography (OCT-A) with corresponding B scan angio flow of the superficial capillary plexus (SCP) shows a preserved macular flow with some areas of flow reduction along the vascular arcade due to the underlying outer retinal atrophy. (D) En face 6 × 6 OCT-A with corresponding B scan angio flow of the choroidal slab shows a diffuse loss of vasculature with a relatively preserved island of flow in the foveal region.