Abstract
Purpose:
Eyes with a high cup-to-disc ratio (CDR) or CDR asymmetry are sometimes categorized separately as “glaucoma suspect”. Whether cupping is attributed to prelaminar thinning and/or posterior bowing of the LC in glaucoma suspect has not been determined. We investigated the lamina cribrosa (LC) depth and its relationship with the CDR in the eyes with generalized enlargement of 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 (ONH) 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 ONH in both eyes.
Results:
Disc area and CDRs were larger in glaucoma suspect group than control group (P<0.001). The mean LC depth was significantly greater in disc-area matched glaucoma suspect group compared to the normal control group ((interindividual comparison, P < 0.001). The mean LC depth was negatively correlated with the average and vertical CDRs (r = −0.746 and −0.658, respectively; both P < 0.001), which was maintained after controlling for the disc area (r = −0.749 and −0.641, respectively; both P < 0.001). In eyes with CDR asymmetry, the LC was located more posteriorly in eyes with a higher CDR compared to fellow eyes with a lower CDR ((inter-eye comparison, P < 0.001).
Conclusions:
The LC depth was greater in eyes with generalized enlargement of cupping as well as in eyes with a higher CDR than fellow eyes, and was negatively related to the CDR. These results suggest that the clinical appearance of cup enlargement or cupping has LC displacement components.