Optical coherence tomography angiography of the macular microvasculature changes in retinitis pigmentosa

To investigate the macular microvasculature changes by optical coherence tomography angiography (OCTA) and analyse the correlation between these changes and central visual function in patients with retinitis pigmentosa (RP).

We measured the area of the foveal avascular zone (FAZ) and the foveal and parafoveal flow density (FFD and PFD, respectively) in the superficial (S) and deep (D) retinal plexus by OCTA (AngioVue) and compared these values between 73 RP patients and 36 healthy controls. We analysed the relationships between these microvasculature measurements and central visual functions such as visual acuity (VA) and the values of static perimetry tests (Humphrey Field Analyzer, the central 10-2 program) in the RP patients.

The FFD-S, PFD-S and PFD-D were significantly decreased in the RP patients compared to the controls (all p < 0.05), whereas there was no significant difference in the FAZ-S, FAZ-D or FFD-D (all p > 0.05). A subgroup analysis showed that the RP patients with VA <20/20 had increased FAZ-S compared to the controls and RP patients with VA ≥20/20 (p = 0.01 and p = 0.007, respectively). Spearman rank testing demonstrated that PFD-S and PFD-D were significantly correlated with all of the central visual parameters (all p < 0.01). The FAZ-S and FFD-S were significantly correlated with VA, and FAZ-D and FFD-D showed no significant correlation.

Both the superficial and deep layers of the parafoveal microvasculature are attenuated in RP and correlated with reduced central visual function. The foveal microvasculature, especially in the deep layer, was relatively preserved until mild-to-moderately advanced stages.