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

Abstract

Citation: Fard MA, Afzali M, Abdi P, et al. Optic nerve head morphology in nonarteritic anterior ischemic optic neuropathy compared to open-angle glaucoma. Invest Ophthalmol Vis Sci. 2016;57:4632-4640. DOI:10.1167/ iovs.16-19442 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 spectraldomain optical coherence tomography (SD-OCT). METHODS.In this cross-sectional study, 121 eyes of 91 patients consisted of moderate to severe POAG (n ¼ 32 eyes), visual field mean deviation-matched NAION (n ¼ 30 eyes) and their fellow eyes (n ¼ 30 eyes), and healthy controls (n ¼ 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 ¼ 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.Keywords: open-angle glaucoma, nonarteritic anterior ischemic optic atrophy, lamina cribrosa, optic nerve head, optic atrophy B oth open-angle glaucoma (OAG) as chronic progressive optic neuropathy and nonarteritic anterior ischemic optic neuropathy (NAION) as acute optic neuropathy with inflammation-associated axonal loss cause irreversible damage to the optic nerve.1-3 In contrast to NAION, which presents with disc pallor after an ischemic event, OAG results in the enlargement of the optic disc cup. Optic nerve head (ONH) morphologic features differ in NAION and OAG. While a small disc area and smaller cupping are predisposing risk factors for the development of NAION, [3][4][5]

Optic nerve head cupping in glaucomatous and non-glaucomatous optic neuropathy

“…Hata et al 10 showed that eyes with compressive optic neuropathy had a smaller LC depth than eyes with glaucoma without accounting for the role of choroidal thickness. In another study, we also found that ALD is deeper in glaucomatous cupping than in ischaemic optic neuropathy 13. However, in this study we first found similar posterior displacement of the LC surface and equally deep ALD in NGC and glaucomatous cupping after adjusting for age and axial length.…”

“…The mean of three measurements was defined as the average central prelaminar thickness (PLT) (figure 1D). 13 …”

Optical coherence tomography angiography in acute non-arteritic anterior ischaemic optic neuropathy

“…Surprisingly, the few published studies have shown conflicting results, suggesting either thinning9 or, on the opposite, thickening of the PCT in NAION eyes,34 35 and sometimes in the healthy, opposite eyes, compared with controls. The choroid may be also thinner at the subfoveal level in eyes with NAION, compared with controls, after adjusting for age, optic disc diameter, gender and refractive error 8.…”

Automated Evaluation of Parapapillary Choroidal Microvasculature in Ischemic Optic Neuropathy and Open Angle Glaucoma

“…We also previously showed thick prelaminar tissue using EDI-OCT in NAION eyes comprises a component of crowded optic discs in such eyes. 23,24 It is possible that PPCMv may be increased in NAION, but OCT-A may lack sensitivity to identify such a change, if present. There may be insufficient resolution of compacted vessels in the tight parapapillary space.…”