Optic Nerve Head Morphology in Nonarteritic Anterior Ischemic Optic Neuropathy Compared to Open-Angle Glaucoma.

PURPOSE: To compare optic nerve head (ONH) morphology of optic nerve atrophy between eyes with primary open-angle glaucoma (POAG) and eyes with a history of nonarteritic anterior ischemic optic atrophy (NAION) using enhanced depth imaging (EDI) with spectral-domain optical coherence tomography (SD-OCT).

METHODS

In this cross-sectional study, 121 eyes of 91 patients consisted of moderate to severe POAG (n = 32 eyes), visual field mean deviation-matched NAION (n = 30 eyes) and their fellow eyes (n = 30 eyes), and healthy controls (n = 29). The optic discs were scanned using SD-OCT and measurements were obtained using HEYEX software 6.0. Lamina cribrosa (LC) thickness and anterior lamina cribrosa depth (ALD) at three scans (midsuperior, central, and midinferior) were determined and compared. In addition, prelaminar tissue thickness was measured at three points of a single central scan.

RESULTS

There was no significant difference in the visual field mean deviation (MD) between the NAION and POAG groups (P > 0.99), but both groups had a significantly worse MD than the healthy group (P < 0.001). The NAION and POAG groups had similar peripapillary retinal nerve fiber layer (pRNFL) thickness (P < 0.99). Eyes with POAG had greater ALD and thinner LC than control eyes and NAION eyes in all regions of the ONH (P < 0.001 for both). There was a marked prelaminar tissue thinning in POAG eyes compared to control and NAION eyes (P < 0.001). Lamina cribrosa thickness and ALD of NAION eyes were not different from their fellow eyes and control eyes. Although prelaminar thickness was thinner in NAION eyes compared to their fellow eyes (P = 0.005), it was thicker than in control eyes (P < 0.001).

CONCLUSIONS

Despite profound thinning and posterior displacement of LC in POAG, the thickness and position of LC in NAION eyes are similar to those seen in healthy control and their fellow eyes.