Abstract
Background: Retinitis Pigmentosa (RP) represents a retinal dystrophy with an extremely complex pathogenesis further worsened by the impairment of the retinal vascular supply. The main goal of this study was to identify different vascular patterns in RP, by means of optical coherence tomography angiography (OCTA). Methods: A total of 32 RP patients (16 males, 50%; mean age 45.93 ± 11.4) and 32 healthy age-matched controls (16 males, 50%; age 42.8 ± 11.2). High resolution OCT and OCTA images were obtained from all participants. Several quantitative parameters were extracted both from structural OCT and OCTA images. A post-hoc analysis assessed the relationship between the quantitative OCTA parameters adopted and the following measures: best corrected visual acuity (BCVA), central macular thickness (CMT) and retinal nerve fiber layer (RNFL). Results: Mean LogMAR BCVA was 0.24 ± 0.32 for RP patients and 0.0 ± 0.0 for controls (p < 0.01). CMT, choroidal thickness and RNFL were statistically different between RP and controls (p < 0.01). OCTA parameters showed strong alterations of the retinal vascular network in RP (all p < 0.01). Several statistically significant correlations were also found. Furthermore, a vessel tortuosity cut-off of 4.80 and a vessel rarefaction cut-off of 0.62 enabled the RP cohort to be divided into two significantly different sub-groups in terms of BCVA, RNFL and CMT. Conclusions: Quantitative OCTA parameters help identify vascular abnormalities in RP, separating two different vascular patterns.
Highlights
The term Retinitis Pigmentosa (RP) covers a heterogeneous group of retinal disorders clinically characterized by progressive photoreceptor degeneration, leading to impaired dark adaptation, night blindness, gradual visual field damage, and variable final central vision impairment [1]
A vascular impairment at the level of the peripapillary network has been described [9]. These findings proved useful in attaining a better understanding of the progression of degenerative phenomena leading to the loss of integrity in both inner and outer retinal layers, the limitations of the current optical coherence tomography angiography (OCTA) analysis are related to the fact that the method provides only morphological information
vessel density (VD) analyses of RP patients revealed statistically significant reductions for all macular and optic nerve head vascular plexa compared with the control group, the only exceptions being nSCP (p = 0.053) and nCC (p = 0.081)
Summary
The term Retinitis Pigmentosa (RP) covers a heterogeneous group of retinal disorders clinically characterized by progressive photoreceptor degeneration, leading to impaired dark adaptation, night blindness, gradual visual field damage, and variable final central vision impairment [1]. Structural optical coherence tomography (OCT) and OCT angiography (OCTA) have provided further information useful in understanding RP pathogenesis better These techniques are able to investigate retinal microstructural features non-invasively, providing histologically comparable information on the involvement of each retinal layer and the integrity of the retinal vascular network. A vascular impairment at the level of the peripapillary network has been described [9] These findings proved useful in attaining a better understanding of the progression of degenerative phenomena leading to the loss of integrity in both inner and outer retinal layers, the limitations of the current OCTA analysis are related to the fact that the method provides only morphological information. Conclusions: Quantitative OCTA parameters help identify vascular abnormalities in RP, separating two different vascular patterns
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