Microvascular and metabolic alterations in retinitis pigmentosa and Stargardt disease

Purpose The aim of our study was to evaluate retinal microvascular changes recorded with optical coherence tomography angiography (OCTA) and the metabolic function measured with retinal oximetry (RO) in patients with retinitis pigmentosa (RP) and Stargardt disease (STGD). Methods In this prospective, noninterventional study, OCTA and RO were performed on 107 eyes (56 subjects): 53 eyes diagnosed with RP without the presence of macular oedema (no-ME-RP), 26 eyes with STGD, and 28 control eyes. Main outcome measures were the mean superficial (FAZ-S; mm(2)) and deep foveal avascular zone (FAZ-D; mm(2)) measured with OCTA as well as the mean arterial (A-SO2; %), venular (V-SO2; %) oxygen saturation, their difference (A-V SO2; %) and the corresponding mean diameters of the peripapillary retinal arterioles (D-A; mu m) and venules (D-V; mu m) determined with RO. Results Stargardt disease (STGD) patients differed from controls and no-ME-RP by an enlarged FAZ-S and reduced A-SO2 and V-SO2 (p <= 0.013). No-ME-RP eyes presented with attenuated vessels (p < 0.001) and increased A-SO2 and V-SO2 (p <= 0.012) compared to controls and STGD. The FAZ-D showed significant interactions with A-SO2 (p = 0.003) in no-ME-RP while the FAZ-S correlated with visual acuity in no-ME-RP (p = 0.007) and STGD (p = 0.034). Conclusion Retinitis pigmentosa (RP) and Stargardt disease (STGD) patients suffer from microvascular and metabolic alterations, however, showing a different pattern. A combined microvascular-metabolic model may therefore allow to more precisely characterize RP and STGD as well as presumably other inherited retinal diseases.