Inner limiting membrane bridges within Bruch's membrane defects in pathological myopia

Abstract

AbstractPurpose: To examine peculiarities of the inner limiting membrane (ILM) in axially elongated eyes.Methods: The histomorphometric study included human globes enucleated due to reasons such as painful secondary angle‐closure glaucoma or malignant uveal melanomas. Using light microscopy, we searched for regions with ILM‐specific features in association with a marked axial elongation.Results: Out of 279 eyes (279 patients) (mean age: 61.8 ± 13.9 years; axial length: 25.5 ± 3.1 mm (range: 20.0–37.0 mm)), two eyes (axial length: 30 mm and 34 mm, respectively) showed one region and two regions, respectively, characterized by ILM presence and absence of all other retinal layers, retinal pigment epithelium, Bruch's membrane (BM) and choroid. The length of these regions, called ILM‐bridges, was 1.06, 0.73, and 0.62 mm, respectively. All ILM‐bridges were spatially associated with a larger, underlying BM defect and with localized scleral thinning without a staphylomatous scleral configuration. The distance between the ILM‐bridges and the optic disc ranged between 1.92 and 4.21 mm. In univariable analysis, ILM‐bridge number increased with longer axial length (beta: 0.19; p = 0.002) and higher BM defect prevalence (beta: 0.21; p = 0.001), while in multivariable analysis, the ILM‐bridges number remained to be significantly correlated with a higher prevalence of BM defect (beta: 0.15; p = 0.048).Conclusions: ILM‐bridges are a hallmark of pathologic myopia and occur in spatial association with underlying, larger BM defects. ILM‐bridges may be due to a local stretching and rupture of all other retinal layers, caused by the BM defect‐related enlargement of the retinal underground, with the ILM as a basal membrane presenting the highest resistance against the stretching‐associated biomechanical force.