Background: In anterior ischemic optic neuropathy (AION), it is important not to miss the diagnosis of giant cell arteritis (GCA) because this requires immediate steroid treatment to prevent involvement of the second eye and possible blindness. A missed diagnosis also might lead to fatal systemic complications.
Materials and methods: Observational case report.
Results: A 79-year-old woman noticed decreased visual and visual field loss in the right eye. At presentation, right visual acuity was 10/20 (ETDRS chart 2000). There was a right relative afferent pupillary defect of 0.6 log units. Asked for symptoms of GCA she complained about temporal and occipital headache, jaw claudication combined with malaise, and myalgia of the upper limbs. Laboratory tests showed normal inflammatory markers. Repeated tests confirmed ESR and CRP to be within the normal range. GCA being suspected, ultrasound of the superficial temporal arteries and temporal artery biopsy were performed unilaterally on the right side. Histology showed a chronic inflammatory cell infiltrate consistent with active GCA. The patient was treated with high-dose corticosteroids (250 mg methylprednisolone, three times/day, initially) and symptoms rapidly resolved, but visual loss remained unchanged.
Conclusion: The case presented here proves that GCA with typical related visual loss (AION) is possible even when both ESR and CRP are in the normal range. Therefore, in the presence of typical symptoms, the clinician must not rely solely on laboratory testing, but start steroid therapy immediately and order a temporal artery biopsy.