Lamina cribrosa depth is associated with the cup-to-disc ratio in eyes with large optic disc cupping and cup-to-disc ratio asymmetry

Purpose: To investigate the lamina cribrosa (LC) depth and its relationship with the cup-to-disc ratio (CDR) in the eyes with generalized increased optic disc cupping and CDR asymmetry. Methods: Glaucoma suspect subjects with a CDR≥0.7, CDR asymmetry ≥0.2 in the absence of visual field (VF) loss, and normal control subjects were enrolled. The optic nerve head was imaged using the enhanced depth imaging modes of Spectralis optical coherence tomography. The LC depth was determined at the mid-horizontal, and the superior and inferior mid-peripheral regions of the optic nerve head. Results: Disc area and CDRs were larger in the glaucoma suspect group compared with the control group (P<0.001). The mean LC depth was significantly greater in the disc area-matched glaucoma suspect group compared with the normal control group (P<0.001). The mean LC depth was positively correlated with the average and vertical CDRs (r=0.755 and 0.664, respectively; both P<0.001), which was maintained after controlling for the disc area (r=0.756 and 0.645, respectively; both P<0.001). In eyes with CDR asymmetry, the LC was located more posteriorly in eyes with a higher CDR compared with fellow eyes with a lower CDR (P<0.001). Conclusions: The LC depth was greater in eyes with generalized increased cupping, as well as in eyes with a higher CDR than fellow eyes, and was significantly related to the CDR. These results suggest that the clinical appearance of cup enlargement or cupping has LC displacement components.