Diagnostic Dilemma: Incipient Non-Arteritic Anterior Ischemic Optic Neuropathy vs. Steroid-Responsive Inflammatory Optic Neuropathy.

Abstract

Objective: To highlight the diagnostic challenge of differentiating incipient non-arteritic anterior ischemic optic neuropathy (NAION) from inflammatory optic neuropathy in resource-limited settings.

Methods: A male in his mid-50s with four days of painless progressive left-eye vision loss. Examination: OD crowded disc (CDR 0.3), OS 360°-disc edema (OCT RNFL 182 μm), Grade 1 RAPD, 360° visual field constriction. Investigations: OCT 30-2 fields, FFA (delayed disc filling, late leakage), HRCT brain/orbit, B-scan (ONSD 6.02 mm), labs (BP 126/82, PP2BS 146 mg/dL, elevated lipids and ESR, nonreactive VDRL). Treatment: aspirin 75 mg OD + prednisolone 1 mg/kg OD for a one-week trial.

Results: At one week: OS edema resolved (RNFL 104 μm), vision improved to 6/9 OS, RAPD resolved; steroids tapered over 10 days. At two weeks: OS 6/6, fields markedly improved. At 10 weeks: maintained on pred 5 mg OD + aspirin; no recurrence.

Discussion: The case highlights the complexity of distinguishing incipient NAION from steroid-responsive inflammatory optic neuropathy, particularly when clinical and angiographic features overlap. The dramatic improvement following a short steroid trial suggested an underlying inflammatory component despite the presence of structural risk factors for NAION. This therapeutic response emphasizes the diagnostic value of monitored steroid trials in ambiguous presentations. In resource-limited environments, such an approach may offer a pragmatic adjunct to standard diagnostic protocols.

Conclusions: Rapid steroid response favored an inflammatory component over pure NAION. A crowded OD disc predisposed to NAION underscores the necessity for nuanced, individualized management. Therapeutic trials may aid diagnosis where advanced tests are inaccessible.