Focal LC defects correlate with occurrence of neuroretinal rim and visual field loss

Focal lamina cribrosa (LC) occurs in conjunction with neuroretinal rim and visual field loss, claims a study in the Archives of Ophthalmology.

Dr Saman Kiumehr et al., Department of Ophthalmology, New York University School of Medicine, New York, USA, compiled a study on 92 eyes of 46 healthy participants and 45 eyes of 31 participants with glaucoma.

All subjects underwent serial horizontal and vertical enhanced depth imaging of the optic nerve head with optical coherence tomography (OCT). Anterior laminar surface irregularity constituted as focal LC defects and spatial consistency was assessed among focal LC defects, neuroretinal rim thinning/notching and visual field defects.

Although there were no LC defects in the healthy eyes there were 98 focal LC defects with various patterns of severity identified in 34 glaucomatous eyes. In the remaining 11 glaucomatous eyes, seven presented with a deeply excavated optic disc.

In the eyes with LC defects 11 had an acquired pit of the optic nerve and the remaining defects occurred due to neuroretinal rim thinning/notching. The majority of defects occurred in the inferior/inferotemporal far periphery of the LC.

Greater sensitivity loss was found in the eyes with focal LC defects limited to the inferior half of the optic disc. Focal loss of laminar beams in glaucoma could cause an acquired pit of the optic nerve.