Vascular Density and Retinal Function in Patients with Retinitis Pigmentosa Evaluated by Swept-Source OCT Angiography and Microperimetry

Purpose: To determine the retinal and choroidal vessel density in the macular area with swept-source optical coherence tomography (OCT) angiography (SS-OCTA) in patients affected by retinitis pigmentosa (RP), to compare their data with those on healthy subjects, and to study a possible morphofunctional correlation by microperimetry (MP-1). Methods: A total of 40 eyes of 40 patients affected by RP and 24 eyes of 24 healthy subjects were included in the study. Manually moving down the segmentation line of the SS-OCTA, we have evaluated the vessel density for the superficial retinal plexus, deep retinal plexus, choriocapillaris, and three levels of the choroid. Results: Linear regression analyses were performed of the retinal structure and function. No significant correlation was detected in any case (R² = 0, p > 0.05). A comparison between RP and healthy controls revealed a significant reduction in SS-OCTA mean capillary density in the RP group (p = 0.0011). This relationship was consistent across vascular layers (p = 0.2413). A significant association between the capillary density of the various vascular complexes was detected within individual eyes (p < 0.0001). Conclusions: This study represents the first comparing MP-1 and SS-OCTA data in the largest cohort of patients. RP patients showed a reduction in both the retinal and the choroidal vascular network in the macular area compared to healthy subjects.