Morphological and functional involvement of the inner retina in retinitis pigmentosa

Background To investigate the morphological retinal parameters associated with retinal sensitivity status in retinitis pigmentosa (RP) through a quantitative multimodal imaging approach. Methods The study was designed as an observational, prospective case series, including RP patients and healthy controls. Multimodal imaging included fundus autofluorescence (FAF), structural optical coherence tomography (OCT), OCT angiography (OCTA) and microperimetry (MP). The follow-up lasted 12 months. For each imaging modality, we performed an overall quantitative analysis and a detailed investigation based on the ETDRS-9 sectors grid. Quantitative parameters included the thickness of each retinal and choroidal layer, vessel density (VD), choriocapillaris porosity (CCP), FAF intensity and MP retinal sensitivity. Results We included 40 eyes (40 patients) affected by RP and 40 healthy eyes (40 controls). Mean baseline BCVA was 0.14 +/- 0.18 LogMAR, with 0.18 +/- 0.24 LogMAR after 1-year of follow-up. RP eyes showed statistically significant alterations of retinal and choroidal layers on the ETDRS-9 sectors grid, significant reduction of VD values and MP retinal sensitivity, and significantly higher CCP than controls. The inner retinal layers proved closely associated with the functional integrity of the posterior pole. In addition, our ROC analysis provided quantitative cutoffs connected significantly with a high probability of observing a partial sparing of MP retinal sensitivity. Conclusions The inner retinal layers are closely associated with the functional integrity of the posterior pole in RP. FAF intensity reduction may be interpreted as lipofuscin metabolism impairment inducing increased phototoxic distress for retinal structures. Vascular involvement contributes to the morpho-functional deterioration of the macular region in RP.

Automated summary

Through multimodal imaging, this study investigated the morphological changes in the retinal and choroidal layers of patients with retinitis pigmentosa (RP). The findings showed significant alterations and reductions in vascular density and retinal sensitivity, as well as increased choriocapillaris porosity in RP eyes. The study also found a close association between the inner retinal layers and the functional integrity of the posterior pole, and vascular involvement contributing to macular region deterioration in RP.