title: Bilateral nonarteritic anterior ischemic optic neuropathy: comparison of visual outcome in the two eyes.
abstract: BACKGROUND
  In patients with bilateral sequential nonarteritic anterior ischemic optic neuropathy (NA-AION), previous studies have reported conflicting results on whether or not the visual outcome is similar in the 2 eyes. The authors investigated this issue in 174 consecutive patients with bilateral NA-AION.
  
  
  METHODS
  At the first visit, all patients had a detailed ophthalmic and medical history and comprehensive ophthalmic evaluation. Visual evaluation was performed by recording Snellen visual acuity and visual fields with kinetic perimetry. The same ophthalmic evaluation was performed at each follow-up visit. The data on the difference in visual acuity, which was converted to logarithm of the minimum angle of resolution (logMAR) form, and visual field defects between the first eye and the second eye of each patient at the initial visit and at the final follow-up were analyzed. A similar subgroup analysis was performed on patients treated with systemic corticosteroids.
  
  
  RESULTS
  At presentation, both initial visual acuity and visual field defects were significantly better in the second eye than in the first eye (P < 0.0001). As a predictor of initial visual acuity in the second eye, the initial logMAR of the first eye only explained 7.0% (R2) of the total variation in the initial logMAR of the second eye. Intraclass correlation (ICC) between the paired eyes was 0.19 (95% confidence interval [CI], 0.04-0.33), indicating poor agreement. The absolute difference in initial visual field grade between the 2 eyes was 0.5 or greater in 78%. The weighted kappa statistic for agreement between visual field defects of the 2 eyes was 0.27 (95% CI, 0.19-0.36), indicating poor agreement. At the final follow-up, a difference in logMAR of at least 0.3 between the paired eyes was found in 38% of the steroid-treated group and 45% of the untreated group. For visual field grade, there was a difference of at least 0.5 in 70% of those who were treated with steroid and in 76% of those not treated. The ICC for logMAR and weighted kappa for visual field grade for the paired eyes was below 0.60 for both the groups. The findings indicated poor agreement between the 2 eyes.
  
  
  CONCLUSIONS
  The results show that in patients with bilateral sequential NA-AION, there are large differences between the visual acuity and visual field findings of paired eyes at initial and final visit, whether or not treated with steroids. It is not possible to predict the visual acuity and visual field grade in the second eye based solely on the first eye.
authors.affiliation: Department of Ophthalmology and Visual Sciences (SSH), College of Medicine, University of Iowa, Iowa City, Iowa; and Department of Biostatistics (MBZ), College of Public Health, University of Iowa, Iowa City, Iowa.
authors.forename: Sohan Singh
authors.initials: SS
authors.lastname: Hayreh
authors.forename: M Bridget
authors.initials: MB
authors.lastname: Zimmerman
mesh_terms: D005123:Eye / Q000503:physiopathology*; D005260:Female; D005451:Fluorescein Angiography; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D018917:Optic Neuropathy, Ischemic / Q000503:physiopathology*; D012189:Retrospective Studies; D013223:Statistics as Topic; D014792:Visual Acuity / Q000502:physiology*; D058609:Visual Field Tests; D014794:Visual Fields / Q000502:physiology*