Changes in the structure of retinal layers over time in non-arteritic anterior ischaemic optic neuropathy.

Abstract

To examine structural changes in retinal layers over time in patients with non-arteritic anterior ischaemic optic neuropathy (NAION) and determine the layers that predict visual outcomes. The optical coherence tomography parameters in NAION eyes at <2 months, 2-5 months, and 6-18 months from the onset were compared to age-matched normal controls. Generalised estimating equation analysis was used to analyse the changes over time and regression analysis was performed to identify the layer that could predict visual field outcomes. Less than 2 months from the onset, the peripapillary retinal nerve fibre layer (RNFL) (p = 0.001) and macular outer nuclear layer (ONL) (p = 0.024) were significantly thicker in the NAION eyes than in the control eyes. The average peripapillary RNFL, macular RNFL, and ganglion cell layer and inner plexiform layer (GCIPL) showed reductions in thickness within 2-5 months (peripapillary RNFL: -19.8 μm/month, p < 0.001, macular RNFL: -14.5 μm/month, p < 0.001, GCIPL: -26.8 μm/month, p < 0.001). The change of thickness in temporal and superior peripapillary RNFL, GCIPL, inner nuclear layer (INL), and ONL by 2-5 months was associated with the final visual field results (p = 0.018, p < 0.001, p = 0.040, p = 0.020, and p = 0.002, respectively). The peripapillary RNFL swelling initially observed started to decrease within 2-5 months along with macular RNFL and GCIPL thinning. The rate of thickness changes in the peripapillary RNFL, GCIPL, INL, and ONL by 2-5 months was associated with visual field outcomes.