Enlargement of optic disc cupping is seen both in glaucoma and in neurologic disorders. In this study we compared the morphology of optic nerve head (ONH) cupping between eyes with primary open-angle glaucoma and eyes with non-glaucomatous cupping with similar cupping using enhanced depth imaging (EDI) with spectral-domain optical coherence tomography (SD-OCT).

In this prospective study, 31 eyes of 31 patients with severe glaucoma and 33 eyes of 19 patients with non-glaucomatous cupping with >0.7 cup-disc ratio were enrolled. Twenty eight healthy controls eyes were also recruited. The optic discs were scanned using EDI OCT and lamina cribrosa (LC) thickness, anterior LC depth (ALD) from Bruch's membrane opening, in central, superior and inferior optic nerve head were measured. Prelaminar tissue thickness was also determined.

There was no significant difference in the cup-to-disc ratio and average peripapillary retinal nerve fiber layer thickness between the glaucoma and nonglaucomatous cupping groups (p>0.99). Glaucomatous and non-glaucomatous eyes had greater ALD and thinner LC than control eyes (p<0.001 for both). Prelaminar thickness, all region ALD, and central and superior LC thickness of glaucoma eyes were not different from nonglaucomatous eyes (all P>0.99). However, inferior LC thickness was thinner in the glaucoma group compared to the non-glaucomatous cupping group (p=0.004).

Posterior displacement of the LC and thinning of the superior and central LC were observed both in glaucoma and non-glaucomatous cupping. Inferior LC thickness was different in glaucomatous eyes from non-glaucomatous eyes.