The characteristics of optical coherence tomography on non-arteritic anterior ischemic optic neuropathy

Abstract

Objective To evaluate the changes of optic nerve head (ONH) and the thickness of peripapillary retinal nerve fiber layer (RNFL) in patients with non-arteritic anterior ischemic optic neuropathy (NAION) using optical coherence tomography (OCT). Methods Circular and cross-sectional OCT scans of an area with a diameter of 3.38 mm surrounding the optic disc were performed for 108 eyes (96 cases) with NAION, including 96 eyes (96 cases) in acute edema phase and 41 eyes (37 cases) in resolving phase. Follow-up period was 2 weeks to 24 months, with an average of 6 months. Results The RNFL was thickener with shallow cup or small cups in the acute edema phase. Comparing with the RNFL in the ischemic sector, the thickness of peripapillary RNFL in the non-ischemic sector was greater in 59 eyes (59 cases, 61%), lesser in 26 eyes (26 cases, 27%) and no difference in 11 eyes (11 cases, 12%). During the treatment NAION eyes were dynamically observed by OCT. While ischemie edema of the optic disc resolved in about two weeks, non-ischemic edema subsided in 3-6 weeks. After 1 month in the resolving phase, the thickness of peripapillary RNFL in the ischemic sector of 35 cases (95%) was thinner than the thickness of non-ischemic sector and fellow normal controls. After 3 month in the resolving phase, 26 cases (70%) showed thinner RNFL of whole optic disc. Conclusion The thickness of RNFL in NAION patientsin acute edema phase is thicker than that in the fellow normal eyes, and is also thicker in ischemic sector than that in non-ischemic sector. In resolving phase, the thickness of RNFL is thinner in NAION eyes than that in the fellow normal eyes. Key words: Optic Neuropathy, Ischemic/diagnosis; Tomography, optical coherence; Nerve fibers; Optic disk