In vivo evaluation of lamina cribrosa deformation in glaucoma.

Glaucoma is a group of optic neuropathies that have in common a slow progressive degeneration of retinal ganglion cells (RGC) and their axons, resulting in a distinct appearance of the optic disc and a concomitant pattern of visual loss. The lamina cribrosa (LC) is a mesh-like structure at the optic nerve head, through which the RGC axons and retinal blood vessels pass. Glaucomatous neuronal death occurs in the retina, optic nerve, lateral geniculate nucleus and visual cortex, but the optic nerve head-especially the LC- is considered to be the primary site of axonal injury. Evaluation of the LC structure may greatly enhance glaucoma diagnostics and our understanding of its pathophysiology. However, only a small portion of the LC is clinically seen through the thin prelaminar neural tissue in the central area of the optic disc. The LC is mostly obscured by the neuroretinal rim in the optic disc region, and by the sclera, choroid, retinal pigment epithelium in the parapapillary region. With enhanced depth imaging optical coherence tomography, different mechanisms of laminar deformation in glaucoma can be demonstrated, and a new structure-structure-function correlation developed.