Retinal Flattening Associated With Photoreceptor Degeneration Leads to the Formation of Staphyloma-Like Morphology in Retinitis Pigmentosa

Purpose: A staphyloma-like morphology has been reported in eyes with retinitis pigmentosa (RP). We investigated retinal curvature in RP using widefield swept-source optical coherence tomography and explored the mechanisms underlying this abnormal morphology. Methods: This retrospective study included 74 eyes with RP and 40 control eyes, all with axial lengths of 22 to 26 mm. The curvature of Bruch's membrane was analyzed in the central and peripheral regions of all eyes. In 37 RP eyes with an ellipsoid zone (EZ) length ≥ 1.5 mm, curvature was further evaluated in EZ-preserved and EZ-defected areas and across the EZ boundary. Results: Central macular curvature was significantly steeper in RP eyes (-23.55 ± 17.56 × 10⁻5 µm⁻1) than in controls (-7.72 ± 6.46 × 10⁻5 µm⁻1), whereas the peripheral retina was significantly flatter in RP (-6.84 ± 10.18 × 10⁻5 µm⁻1, inferior) than in controls (-15.14 ± 4.76 × 10⁻5 µm⁻1). Curvature was steeper in EZ-preserved areas (-30.40 ± 24.34 × 10⁻5 µm⁻1) than in EZ-defected areas (-8.00 ± 6.40 × 10⁻5 µm⁻1). Around the EZ edge, curvature on the central side was significantly steeper than that on the peripheral side. Conclusions: In RP, retinal curvature flattens with photoreceptor degeneration, resulting in relatively steep concavity in the central macula or EZ-preserved regions. These findings suggest that photoreceptor loss contributes to secondary alterations in global retinal and ocular configuration.