Drusen of the retinal pigment epithelium of the parapapillary region

Aims/Purpose: The description of the morphology, the occurrence and the associations of parapapillary drusen of the retinal pigment epithelium (dotRPE).Methods: A histomorphometric analysis of enucleated human eyes using a light microscope.Results: 83 enucleated human eyes (mean axial length 25.9 ± 3.2 mm; range 20.0–35.0 mm) were included for analysis using light microscope. The eyes with parapapillary dotRPE (29 of 83 eyes, 35%) in comparison with the other eyes had a shorter axial length with 24.0 ± 1.8 mm vs 27.0 ± 3.3 mm (p < 0 0.001). Additionally, a higher occurrence (27 of 29 vs 12 of 54 eyes, p < 0.001) and greater girth (213 ± 125 μm vs 96 ± 282 μm, p < 0.0001) of the parapapillary alpha zone. Bruch's membrane (BM) was thicker in the parapapillary beta zone (8.4 ± 2.7 μm vs 3.9 ± 2.0 μm, p < 0.001) and in the parapapillary alpha zone (6.6 ± 3.9 μm vs 4.4 ± 1.5 μm, p = 0.02). Underneath the dotRPE and in the parapapillary alpha zone the choriocapillaris appeared open, while it appeared intact in the center of the parapapillary beta zone. Although BM was thicker (p = 0.001) in alpha zone compared to beta zone, it was thicker in beta zone compared to region outside of either alpha or beta zone (p < 0.001). The thickness of BM outside of the parapapillary zone of alpha or beta was not correlated with either the occurrence of dotRPE (p = 0.47) or the axial length (p = 0.31). A basal membrane stained positive for PAS connected the RPE cells of the parapapillary dotRPE. The cell density of the RPE increased in the alpha zone compared to bordering regions (22.7 ± 7.3 cells/240 μm vs 18.3 ± 4.1 cells/240 μm, p < 0.001). Parapapillary dotRPE occurred in 69% (27 of 39) of eyes with a parapapillary alpha zone.Conclusions:: Parapapillary dotRPE as fibrous pseudo‐metaplasia correlated with a shorter axial length, thicker BM in the alpha and the beta zone, as well as a higher prevalence and larger size of the alpha zone. This may be helpful to set apart the glaucomatous parapapillary beta zone and the myopic beta zone.