Early Optic Nerve Head Swelling Rate Is Associated with Worsening of Visual Outcomes in Nonarteritic Anterior Ischemic Optic Neuropathy

Abstract

Purpose To characterize longitudinal OCT changes in nonarteritic anterior ischemic optic neuropathy (NAION) and to evaluate whether early rates of optic nerve head (ONH) swelling are associated with subsequent visual outcomes. Design Longitudinal cohort study based on a secondary analysis of data from the multicenter randomized QRK207 phase 2/3 NAION trial ( ClinicalTrials.gov identifier, NCT02341560). Participants Seven hundred and fifteen participants with acute NAION were imaged within 14 days of symptom onset. Methods OCT imaging was performed at predefined visits using Cirrus or Spectralis devices. Structural measures included peripapillary retinal nerve fiber layer thickness (pRNFLT), peripapillary optic nerve head volume (pONHV), and macular ganglion cell–inner plexiform layer (mGCIPL) thickness. We analyzed rates of OCT metric change between screening (mean, 8.0 ±3.2 days from symptom onset) and enrollment (mean interval, 2.5 ±1.9 days). Associations between early OCT metrics and visual outcomes at month 6 were assessed using Spearman rank correlations ( r s) and logistic regression. Main Outcome Measures Visual field (VF) total deviation and best-corrected visual acuity (BCVA), with worsening defined as 2-dB or more VF loss or 10-letter or more BCVA loss between enrollment and month 6. Results At presentation, study eyes showed pronounced ONH swelling (mean ± standard deviation: pRNFLT, 241 ±74.8 μm; pONHV, 6.70 ±1.27 mm3), followed by progressive atrophy (month 6: pRNFLT, 56.7 ±14.9 μm; pONHV, 2.7 ±0.41 mm3). Thinning of the mGCIPL was detectable within 14 days of symptom onset (–0.58 μm/day; P < 0.001). Greater rates of ONH swelling between screening and enrollment were associated with subsequent vision change relative to enrollment: each 0.15-mm3/day increase in pONHV conferred higher odds of interval VF worsening (OR, 1.84; 95% CI, 1.3–2.5; P < 0.001) and BCVA worsening (OR, 1.52; 95% CI, 1.1–2.1; P < 0.001) by month 6. Early reduction in swelling was associated with improved outcomes. Similar associations were observed at month 2 with larger effect sizes. Conclusions Increased ONH swelling rates between screening and enrollment were associated with VF and BCVA worsening between enrollment and month 6. Thinning of the mGCIPL is detectable within 14 days of NAION symptom onset, preceding overt structural atrophy. Financial Disclosure(s) Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.