Thinning of the Lamina Cribrosa and Deep Layer Microvascular Dropout in Patients With Open Angle Glaucoma and High Myopia

Abstract

Précis: Lamina cribrosa (LC) thinning (thickness of ≤128.00 µm) helps to distinguish open angle glaucoma from high myopia, which was associated with the presence of microvasculature dropout and elevated intraocular pressure. Purpose: The purpose of this study was to analyze the factors associated with LC thickness in highly myopic eyes with and without open angle glaucoma. Methods: In total, 240 highly myopic eyes with γ-zones (194 eyes without and 46 eyes with open angle glaucoma) were examined, and the LC center, externally oblique border, an abrupt change of scleral curvature (scleral step), deep layer microvasculature dropout and global retinal nerve fiber layer thickness were investigated on optical coherence tomography and optical coherence tomography angiography. Results: LC were thinner in highly myopic open angle glaucoma compared with high myopia alone (107.76±9.86 vs. 137.07±18.51 µm, P<0.001), which was associated with deep layer microvasculature dropout and elevated intraocular pressure. The areas under the receiver operating characteristic curve for detecting open angle glaucoma from the LC thickness was 0.964, which was statistically higher (P<0.05) than from the global retinal nerve fiber layer thickness (0.921) and vertical cup-to-disc ratio (0.902). A LC thickness cutoff value of 128 µm provided 100% sensitivity for detecting open angle glaucoma with 84% specificity. Conclusions: Highly myopic eyes with open angle glaucoma appear to have a thinner LC, which was associated with elevated intraocular pressure and deep layer microvasculature dropout. LC thinning (≤128.00 µm) helps distinguish open angle glaucoma from high myopia with an abnormal retinal nerve fiber layer thickness distribution and unclear shallow disc cupping.