Archetypal analysis quantifies changes in patterns of visual field loss in eyes with acute non-arteritic anterior ischaemic optic neuropathy

Aims We characterised visual field (VF) spatial loss patterns in acute non-arteritic anterior ischaemic optic neuropathy (NAION) using archetypal analysis (AA). Methods We performed standard automated perimetry on 727 participants with acute NAION at screening, day 1 of enrolment, months 2, 6 and 12. We applied AA, an unsupervised machine learning technique, to identify and quantify distinct VF loss patterns (archetypes, ATs). We used Mann-Whitney U tests and Wilcoxon signed-rank tests to assess demographic differences and longitudinal changes in discrete variables, and linear regression to analyse continuous variables. Results AA identified 10 distinct ATs, with three especially prevalent patterns: global VF loss (AT1), inferior altitudinal loss (AT2) and inferior altitudinal with macular sparing (AT3). Between day 1 and month 2, AT1 RW significantly increased from 15.7% to 28.1% (false discovery rate, FDR-adjusted p<0.001). Asian participants consistently exhibited greater RW for AT1 compared with White participants (day 1: 40.7% vs 17.7%; FDR-adjusted p<0.001). Sex differences emerged modestly at months 2 and 6, with females having a higher RW for superior altitudinal loss (FDR-adjusted p=0.049). Older participants showed slightly greater frequency of central horizontal and mild central depression patterns (FDR-adjusted p<0.001). Conclusions AA effectively quantifies distinct, clinically significant VF spatial loss patterns in NAION, revealing significant temporal changes and demographic differences. Global VF loss represents the predominant AT, increasing notably within 2 months of disease onset. Prominent racial disparities, particularly higher severity in Asian individuals, underscore potential differences in NAION aetiology or susceptibility. These findings provide a foundation for improved disease characterisation and prognosis.