Abstract
Purpose:
Defects of the lamina cribrosa (LC) are reported to be present in relatively high proportion of glaucomatous eyes whereas rarely observed in normal eyes. Structural vulnerability of the optic nerve is considered as the most probable reason for this preferential laminar damage in glaucomatous eyes. High myopia is also a risk factor for ocular structural vulnerability. The purpose of this study was to evaluate defects of the laminar cribrosa in highly myopic eyes with and without glaucoma, in comparison with healthy control eyes without high myopia.
Methods:
Serial horizontal optic disc images were obtained using swept-source optical coherence tomography (SS-OCT) 3D raster scan mode from all eyes. Participants were divided into 3 categories; healthy eyes with neither high myopia nor glaucoma (control group), highly myopic eyes without glaucoma (myopia only group), and highly myopic eyes with glaucoma (myopia and glaucoma group), based on the presence or absence of high myopia (axial length>26.5 mm or spherical equivalent refraction ≤ -6 D) and glaucomatous optic neuropathy. Focal LC defects were identified using a standardized protocol by a grader masked to clinical information.
Results:
A total of 118 eyes (83 subjects) were examined, including 20 control eyes (12 subjects), 32 myopia only eyes (27 subjects), and 66 myopia and glaucoma eyes (44 subjects). Focal LC defects were observed in 1 eye (5%) in the control group, 6 eyes (18.8%) in the myopia only group, and 27 eyes (40.9%) in the myopia and glaucoma group. The proportion of having at least one LC defect was significantly different between groups (P=0.0032, Chi-square test).
Conclusions:
Highly myopic eyes without glaucoma showed an increased risk of having a LC defect compared with control eyes. Glaucoma further increased the risk of laminar abnormality. The existence of the LC damage in highly myopic eyes without glaucoma may suggest the risk of future retinal nerve fiber layer damage in those eyes and at least partly explain the increased risk of developing glaucoma in myopic eyes.
Keywords: 577 lamina cribrosa •
550 imaging/image analysis: clinical •
627 optic disc