Retinal and Choroidal Morphological Features Influencing Contrast Sensitivity in Retinitis Pigmentosa

Background and Objectives: To find morphological features on optical coherence tomography (OCT) and OCT-angiography (OCTA) influencing contrast sensitivity (CS) in patients with retinitis pigmentosa (RP). Materials and Methods: Cross-sectional study enrolling 18 eyes of 18 patients with RP. They were examined with CSV1000-E (VectorVision) under mesopic conditions (logarithmic scale), spectral-domain OCT (SD-OCT, Spectralis), swept-source OCT (SS-OCT, Triton), and OCTA (Triton). Automatic thickness measurements of every retinal layer were obtained in grids of 8 × 8 and 10 × 10 cubes. Foveal avascular zone and vascular densities (VD) were also analyzed. Statistical analysis included multiple lineal regression analyses, and a correlation analysis between age, axial length, and intraocular pressure, and retinal nerve fiber layer (RNFL) thickness. Results: Mean age was 47.34 ± 13.77 years. Mean CS with 3, 6, 12, and 18 cycles/degree (c/d) was 1.48 ± 0.37, 1.51 ± 0.39, 1.00 ± 0.42, and 0.44 ± 0.39, respectively. The most related variables to 3 c/d frequency were nasal RFNL thickness (R² = 0.54) and central outer plexiform layer (OPL) (R² = 0.33). In case of 6 c/d frequency, it was central VD in deep plexus (R² = 0.66), and retinal pigment epithelium (RPE) (R² = 0.22). As for 12 c/d frequency, it was central RNFL (R² = 0.50), and central VD in deep plexus (R² = 0.26). Regarding 18 c/d frequency, it was central RNFL (R² = 0.70). Conclusions: Central and nasal RNFL thickness seem to be main predictors of CS in patients with RP, as well as VD in deep retinal plexus. Others with limited influence might be central and nasal OPL thickness, and central RPE thickness.