Short-Term Deterioration of Visual Acuity and Visual Fields in Nonarteritic Anterior Ischemic Optic Neuropathy

To determine the frequency and severity of further visual loss experienced by patients within ten weeks from diagnosis of acute nonarteritic anterior ischemic optic neuropathy (NAION).

Retrospective case series.

Electronic medical records (EMR) at an academic neuro-ophthalmology practice were searched for diagnosis of "NAION" and all identified charts were reviewed to determine eligibility. Patients diagnosed with acute NAION between February 2014 and December 2023 who presented within four weeks of symptom onset and were seen in follow-up within ten weeks were included. Clinically significant decline in best corrected visual acuity (BCVA) and peripheral VF were defined as decline of BCVA ≥2 Snellen lines and decrease of ≥2 decibels (dB) in mean deviation (MD) on perimetric testing.

Forty-nine eyes met inclusion and exclusion criteria. Sixty-seven percent of patients were male and average age at presentation was 66 years. Twenty-two percent of eyes demonstrated worsening of BCVA by ≥2 lines. Of these, 55% worsened by ≥4 lines and 27% by ≥8 lines. In 27% of eyes MD on perimetry worsened by ≥2 dB and in 18% by ≥4 dB. In total, 41% of eyes demonstrated clinically significant worsening of BCVA or VF.

Subacute deterioration of BCVA and/or VF following acute NAION is not uncommon while optic disc edema is present, with sizeable proportion of patients experiencing dramatic visual decline. Deterioration in visual function within the first 10 weeks of presentation does not exclude the diagnosis of NAION and further investigations should only be performed if additional clinical features are discordant with this diagnosis.