Optical coherence tomography angiography (OCT-A) in retinitis pigmentosa and macular dystrophy patients: a retrospective study

Abstract

Purpose: To evaluate macular vascular abnormalities in patients with macular dystrophies (MD) and retinitis pigmentosa (RP) through application of optical coherence tomography angiography (OCT-A).

Methods: In this retrospective study, patients with MD and RP were examined by OCT-A and compared to healthy individuals. OCT-A images were analyzed regarding the diameter and surface area of the foveal avascular zone (FAZ) as well as flow (FL) in different retinal layers (superficial vascular complex (SVC), intermediate capillary complex (ICP), deep capillary complex (DCP), choriocapillaris (CC), and choroid (CD)).

Results: Twenty-one patients with MD, 21 patients with RP without macular edema (RPnE), 8 patients with RP with edema (RPwE), and 41 healthy individuals were enrolled. The group of MD and RPnE patients showed none or only minor changes in FAZ. In RPwE patients, the FAZ was significantly smaller in vertical and horizontal measurements and surface area in SVC, whereas it was markedly enlarged in ICP. FL was significantly reduced compared to healthy individuals by an average of 13.2% in CD, 14.2% in CC, and 8.4% in DCP in all patient groups. In ICP, the reduction was 9.2% for RPnE and 12.7% for RPwE patients. The SVC showed reduced FL in the MD (8.1%) and RPnE (10.3%) group.

Conclusions: OCT-A is a valuable tool to examine retinal vascular abnormalities in patients with MD and RP. OCT-A revealed a reduced flow in various retinal layers in MD, RPnE, and RPwE. Alterations of the FAZ were less distinct in these groups which add to the variation reported previously.

Keywords: Inherited retinal dystrophy; Macula dystrophy; Optical coherence tomography angiography; Retinal imaging; Retinitis pigmentosa.

Fig. 1

Horizontal foveal OCT b-scan in an OCT-A examination of a healthy individual. The red-dotted lines show the limits of the selected slabs, the yellow pixels represent areas where the OCT-A scan detected relevant blood flow. (SVC. superficial vascular complex; ICP, intermediate capillary plexus; DCP, deep capillary plexus; CC, choriocapillaris; CD, choroid)

Fig. 2

OCT-A of a patient with MD. Top left shows a transverse structural OCT scan of the selected slab (SVC) of the examined macular area (size 3.2 mm by 3.2 mm). Top right shows the OCT-A of the examined area. The vertical blue and horizontal green arrow in the top row en-face pictures correspond with the OCT B-scan in the bottom left and bottom right, which show the selected OCT-A slab marked by two dotted lines and the flow as yellow dots

Fig. 3

OCT-A of a RPwE patient. Top left shows a transverse structural OCT scan of the selected slab (SVC) of the examined macular area (size 3.2 mm by 3.2 mm). Top right shows the OCT-A of the examined area. The vertical blue and horizontal green arrow in the top row en-face pictures correspond with the OCT B-scan in the bottom left and bottom right, which show the selected OCT-A slab marked by two dotted lines and the flow as yellow dots

Fig. 4

OCT-A of a RPnE patient. Top left shows a transverse structural OCT scan of the selected slab (SVC) of the examined macular area (size 3.2 mm by 3.2 mm). Top right shows the OCT-A of the examined area. The vertical blue and horizontal green arrow in the top row en-face pictures correspond with the OCT B-scan in the bottom left and bottom right, which show the selected OCT-A slab marked by two dotted lines and the flow as yellow dots

Fig. 5

Variation of the area of the foveal avascular zone (FAZ) in the intermediate capillary plexus (ICP). Extrema deviating more than 1.5 times but less than 3 times the interquartile range (IQR) from the box are marked with a dot as potential outliers

Fig. 6

Boxplots of the flow analysis. Extrema deviating more than 1.5 times but less than 3 times the interquartile range (IQR) from the box are marked with a dot as potential outliers. Extrema deviating more than 3 times the IQR are marked as a star