Vessel density analysis in patients with retinitis pigmentosa by means of optical coherence tomography angiography

Aims To describe the vascular abnormalities in patients affected by retinitis pigmentosa (RP) by means of optical coherence tomography angiography (OCT-A). Methods Cross-sectional case series; patients with RP presenting at the Medical Retina Service of the Department of Ophthalmology, University Vita-Salute San Raffaele in Milan were recruited. Inclusion criteria were: diagnosis of RP, clear ocular media, adequate pupillary dilation, and stable fixation. Patients underwent best-corrected visual acuity (BCVA), biomicroscopy, shortwavelength fundus autofluorescence (SW-FAF), and 3x3 Swept Source OCT-A. 30 healthy subjects were chosen as controls. The main outcome was identification of abnormalities in density of the superficial capillary plexus (SCP) and deep capillary plexus (DCP), along with abnormalities of the choriocapillaris (CC). Results 16 patients (32 eyes) were recruited (6 females, 37.4%). Mean age was 53 +/- 18 years; mean BCVA was 0.5 +/- 0.3 LogMAR. Vessel density analysis disclosed a statistical significant difference in the SCP (29.5 +/- 6.8 vs 34.1 +/- 4.3; p= 0.009) and in the DCP (28.7 +/- 7.5 vs 35.5 +/- 5.7; p= 0.001) between the patients and the controls. No difference was found at the level of the CC (51 +/- 4.4 vs 51.3 +/- 2.2; p= 0.716). RP patients showed a bigger foveal avascular zone at the DCP level compared to controls (p<0.001). Conclusions This study showed that most of the vascular impairment in patients affected by RP localised in the DCP, with relative sparing of the SCP and CC. DCP alterations were more pronounced outside the hyper-autofluorescent ring on SW-FAF. Vascular impairment may preclude good treatment outcomes in RP patients.