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  • Asymptomatic NAION Is Common in Fellow Eyes

    By Lynda Seminara
    Selected by Prem S. Subramanian, MD, PhD
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    Journal Highlights

    Journal of Neuro-Ophthalmology
    Published online June 23, 2022

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    Although sequential nonarteritic anterior ischemic optic neuropathy (NAION) occurs in about 15% of patients within five years of the initial episode, the prevalence of presumed previous asymptomatic NAION in fellow eyes is not known. Barbosa et al. reviewed the medical records of pa­tients with acute NAION to determine the frequency of a visual field (VF) defect in fellow eyes that had appeared asymptomatic. They found that 10% of fellow eyes exhibited a VF abnormality suggestive of NAION, which had not been detected previously. All defects occurred in a hemifield.

    The study included 139 patients with a diagnosis of acute NAION who were seen at the authors’ neuro-oph­thalmology facility during a period of nearly six years, ending in September 2021. Data collected from the medical charts included NAION risk factors (e.g., diabetes, hypertension, dyslipid­emia, obstructive sleep apnea, smoking history), VA data for both eyes, ocular exam results, mean deviation and shape of VF defect on automated 24-2 perim­etry in both eyes, and OCT-measured thickness of the peripapillary retinal nerve fiber layer (RNFL) and ganglion cell complex–inner plexiform layer (GCC-IP). VF defects were classified as diffuse, altitudinal (superior or inferior), or nerve fiber bundle (supe­rior or inferior). A VF was presumed to indicate previous NAION if there was corresponding pallor of the optic nerve head and OCT evidence of RNFL or GCC-IP thinning, after all other possible causes of the defect were ruled out. Any VF with more than 33% of fixation losses or more than 15% false positives were considered unreliable and excluded from analysis, as were patients who lacked VF or OCT data, did not return for follow-up, or had an ocular comorbidity that may have impeded analysis (e.g., prior stroke or retinal detachment).

    Each patient who qualified for the analysis had reliable VF data. VF defects were present in the fellow eyes of 63 patients (45.3%), and 54 defects (38.8%) were deemed to represent previous NAION. In 14 (10.1%) of the patients, a presumed prior episode of fellow-eye NAION was asymptomatic. All VF defects in asymptomatic eyes occurred in a hemifield, accompanied by new VF loss in the symptomatic eye. The most common defect in asymptomatic eyes was inferior altitudinal defect-sparing fixation (50%). In five patients, the type of defect was similar in both eyes.

    This study demonstrates that a “previous presumed asymptomatic episode of NAION in the fellow eye of patients presenting with acute NAION is not uncommon,” said the authors. They noted that clinicians may wish to reassure appropriate patients of the low risk of subsequent NAION events. 

    The original article can be found here.