Microvascular and metabolic alterations in retinitis pigmentosa and Stargardt disease

Abstract

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-SO 2 ; %), venular (V-SO 2 ; %) oxygen saturation, their difference (A-V SO 2 ; %) and the corresponding mean diameters of the peripapillary retinal arterioles (D-A; lm) and venules (D-V; lm) determined with RO. Results: Stargardt disease (STGD) patients differed from controls and no-ME-RP by an enlarged FAZ-S and reduced A-SO 2 and V-SO 2 (p ≤ 0.013). No-ME-RP eyes presented with attenuated vessels (p < 0.001) and increased A-SO 2 and V-SO 2 (p ≤ 0.012) compared to controls and STGD. The FAZ-D showed significant interactions with A-SO 2 (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.

The Presence of Hyperreflective Foci Reflects Vascular, Morphologic and Metabolic Alterations in Retinitis Pigmentosa

“…A further finding of our study is the attenuated peripapillary retinal vessels in RP eyes when compared to the controls. Our results are in accordance with several studies, which also found the diameter of the retinal vessels to be narrower in RP in comparison to controls [ 22 , 23 , 24 ]. The authors explained these findings with the assumption for complex vascular impairment is thought to be induced by neurovascular remodeling.…”

“…Previous agreeing studies found a further diminished blood flow in the retinal and choroidal vessels of RP [ 61 , 78 ]. Furthermore, significant narrowing of the peripapillary vessels as well as reduced superior foveolar avascular zone and deep foveolar avascular zone in RP patients were confirmed in a study of Della Volpe et al [ 24 ]. All of these findings supposed reduced metabolic demand as a result of photoreceptors loss in RP.…”

“…In agreement with the data to date [ 38 , 39 , 40 , 41 ], the current study confirms again, that RP patients have an increased number of HRF compared to controls. Furthermore, the present study shows that the retinal vessel diameters are affected in RP [ 22 , 23 , 24 ]. Consistent with the results of published studies [ 22 , 23 , 33 , 34 , 36 , 37 ], we found once again an increased A-SO 2 and even more, an increased V-SO 2 in in RP group.…”

“…The authors explained these findings with the assumption for complex vascular impairment is thought to be induced by neurovascular remodeling. According to this data, the amount of retinal vessel attenuation should be proportional to the tissue remodeling occurring in RP patients [ 59 , 60 , 61 ] and thus, to the residual retinal function and structure [ 22 , 23 , 24 , 62 ]. Our RP group was distinguished from controls through this sign also.…”

“…A further hallmark is the retinal vessel attenuation, affecting primarily the arteriolar, and later on the venular vessels [ 22 , 23 , 24 ].…”