Choriocapillaris, photoreceptor and inner retinal layers in spatial relationship to parapapillary alpha, beta, gamma and delta zone

Aims/Purpose: To examine the spatial relationships between the choriocapillaris, retinal layers and retinal pigment epithelium (RPE) in the parapapillary region.Methods: Human eyes enucleated due to uveal melanomas or secondary angle‐closure glaucoma were histomorphometrically examined.Results: The investigation consisted of 100 globes. In non‐highly myopic non‐glaucomatous eyes, the photoreceptor layer, choriocapillaris and retinal inner nuclear layer (INL) ended approximately at the end of the RPE layer, with no significant (all p ≥ 0.10) difference between the layers. In the non‐highly myopic, glaucomatous eyes and the highly myopic eyes, the photoreceptor layer, choriocapillaris and inner nuclear layer ended in the majority of eyes beyond the RPE‐end in direction to the optic disc border, with the INL extending beyond the RPE‐end significantly more than the photoreceptor layer (non‐highly myopic non‐glaucomatous group: 133 ± 183 μm versus 66.5 ± 96.8 μm; p = 0.001; highly myopic glaucomatous eyes: (266 ± 395 μm vs. 211 ± 286 μm; p = 0.03). A larger extension of the photoreceptor layer, choriocapillaris and INL beyond the RPE‐end correlated with longer axial length (beta: 0.50; B: 32.2; 95% CI: 21.6, 42.8) and wider beta zone (beta: 0.28; B: 0.10; 95% CI: 0.04, 0.16), with longer axial length (beta: 0.24; B: 23.0; 95% CI: 1.6, 44.5) and longer beta zone (beta: 0.59; B: 0.32; 95% CI: 0.22, 0.41; p < 0.001), and with longer axial length (beta: 0.34; B: 43.7; 95% CI: 11.6, 75.7), longer gamma zone (beta: 0.52; B: 0.28; 5% CI: 0.15, 0.41) and diagnosis of non‐highly myopic glaucoma (beta: 0.28; B: 267; 95% CI: 80.8, 454), respectively.Conclusions: Non‐glaucomatous non‐highly myopic eyes differ from highly myopic eyes and glaucomatous eyes in the spatial relationship of the parapapillary tissue layers. The findings support the notion of an axial elongation‐associated shifting of the parapapillary RPE and Bruch's membrane for development of myopic beta zone, and an RPE‐cell loss for development of glaucomatous beta zone.