Microvascular quantitative metrics in retinitis pigmentosa using optical coherence tomography angiography

Aims: To describe the changes in vessel density (VD) using optical coherence tomography angiography (OCTA) of the different sectors in the macular area between retinitis pigmentosa (RP) patients and controls.

Methods: Observational case-control study. We initially included 22 patients with RP and 21 controls. We obtained 6 × 6 OCTA images of the macular area using Angio-OCT SS-DRI-Triton 1.22 (Topcon, Japan), together with visual acuity, biomicroscopy, visual field and optical coherence tomography examination. We compared the VD values in both groups for both superficial (SVP) and deep vascular plexus (DVP). Correlation between VD and macular thickness was also calculated.

Results: The mean visual field index (VFI) in the RP group was 26.11% (±17.29). VD was significantly lower in the RP group compared with healthy controls in all sectors of the DVP (Superior 43.48 ± 3.79 vs 48.86 ± 2.62, P < .0001; Nasal 40,52 ± 4.30 vs 46,01 ± 3.23, P = .0002; Inferior 42.76 ± 5.26 vs 50.10 ± 3.36, P < .0001; Temporal 40.42 ± 4.46 vs 46.09 ± 2.91, P = .0001) and in all but nasal sector in the SVP (Superior 39.86 ± 4.46 vs 46.47 ± 2.61, P < .0001; Nasal 40.35 ± 4.56 vs 44.09 ± 2.87, P = .0067; Inferior 40.74 ± 4.61 vs 46.58 ± 3.26, P = .0002; Temporal 39.98 ± 5.07 vs 44.78 ± 3.28, P = .0024). Correlation between VD and macular thickness was positive and significant (RP: r = 0.59, P = .043; controls r = 0.51, P = .018).

Conclusions: Patients with advanced forms of RP have less vessel density in the macular area than healthy subjects. These differences are present in all four quadrants in the DVP and three in the SVP.