Two Cases of Segmental Disc Oedema and Normal Visual Acuity in Giant Cell Arteritis.

Giant cell arteritis (GCA) frequently involves the ocular circulation. Arteritic anterior ischemic optic neuropathy (AAION) is the most common presentation, producing severe vision loss with a characteristic waxy pallor of the optic disc. Optic disc ischemia in AAION is related to underlying systemic vasculitis, which must be treated aggressively with systemic steroids in order to minimize the risk of fellow eye involvement. In contrast, non-arteritic AION (NAION) is thought to result from localized hypoperfusion of the posterior ciliary arteries and mainly presents with segmental optic disc oedema. This condition is usually seen in individuals with crowded optic discs as well as predisposing vascular risk factors and does not require specific treatment. Distinguishing these two entities is important and often challenging. We describe two cases of biopsy-confirmed AAION presenting as segmental disc oedema with the absence of pallor, suggesting specific and isolated involvement of the posterior ciliary arteries in GCA affecting the ophthalmic circulation. This emphasizes the importance of maintaining a high index of suspicion for GCA, particularly when atypical features are present or systemic findings accompany acute vision loss.