The common causes of unilateral disc oedema include nonarteritic anterior ischaemic optic neuropathy (NAION) and optic neuritis (ON). As prolonged disc oedema may affect visual function, early differentiation is crucial. Therefore, this study compared the resolution time and rate of disc oedema between NAION and ON cases and identified correlated clinical factors. In this retrospective, cross-sectional comparison study, unilateral NAION or ON cases, in which disc oedema was confirmed through fundus photography, were reviewed. Optical coherence tomography data, such as structural changes in the peripapillary retinal nerve fibre layer thickness (pRNFLT), ganglion cell layer thickness at two time points of the first diagnosis, and stable states with subsided disc oedema, were analysed. The severity, resolution rate, and duration of disc oedema were compared between the two groups. This study included 33 eyes each with NAION and ON (mean age: NAION, 69.1 ± 11.8 years; ON, 61.7 ± 15.7 years). No significant differences were observed in sex, visual acuity at diagnosis, colour vision, or visual field defect severity. Mean periods of disc oedema were 1.5 ± 0.6 months in NAION and 1.3 ± 0.7 months in ON cases. At diagnosis, the mean pRNFLT in NAION cases (215.7 ± 57.6 μm) was not different from that in ON cases (199.1 ± 60.4 μm); the resolution rate of disc oedema was not significantly different between the two diseases. The resolution rate of disc oedema—which did not differ significantly—cannot be used to distinguish between NAION and ON. In both diseases, greater initial disc oedema was associated with a longer duration of oedema, but the rate of oedema resolution was faster, resulting in a narrower gap in total resolution time between mild and severe cases. Clinical trial number: not applicable. This retrospective study was approved by the Daegu Catholic University Hospital Institutional Review Board (IRB) for Human Studies (IRB number: 2025-03-012). All procedures adhered to the tenets of the Declaration of Helsinki. Informed consent was obtained verbally from all participants, with their guardians and residents as witnesses.
Moon et al. (Sun,) studied this question.