Macular Features in Retinitis Pigmentosa: Correlations Among Ganglion Cell Complex Thickness, Capillary Density, and Macular Function

PURPOSE: To investigate correlations among macular ganglion cell complex (GCC) layer thickness, macular capillary density, and macular function in patients affected by retinitis pigmentosa (RP). METHODS: Fourteen patients (28 eyes) with previous diagnosis of RP were enrolled. The diagnosis of these conditions was made based on both clinical features and electrophysiological examination. All patients underwent a complete ophthalmologic examination, including optical coherence tomography angiography (OCTA) and multifocal electroretinogram (mfERG). Main outcome measures were macular GCC layer thickness; superficial capillary plexus (SCP) vessel density; deep capillary plexus (DCP) vessel density; choriocapillaris plexus (CCP) vessel density; and amplitudes of mfERG N1 and P1 waves. RESULTS: Average GCC thickness was significantly thinner in RP patients (76.0 ± 25.1 and 109.2 ± 17.5 μm, P = 0.028). Superficial capillary plexus density was 42.2 ± 3.4% in the RP group and 51.4 ± 2.3% in the control group (P < 0.001). Deep capillary plexus density was reduced in RP patients (42.7 ± 6.2%) after the comparison with healthy subjects (56.6 ± 2.2%, P < 0.001). Choriocapillaris plexus density was significantly less in RP patients than in the control group (65.3 ± 2.7% and 67.2 ± 1.4%, P = 0.024). Superficial capillary plexus and DCP density were significantly correlated with both mfERG values and GCC thickness. CONCLUSIONS: We showed that both choroid and retinal vessels were modified in RP patients after comparison with healthy subjects. Moreover, we demonstrated that the SCP and DCP vessel densities are correlated with the macular function, as well as with the GCC thickness.