Anterior clinoid mucocoele presenting as progressive fluctuating visual loss mimicking inflammatory optic neuropathy

Optic nerve lesions usually produce monocular visual loss, and in compressive optic neuropathies, gradual vision loss is the more usual presentation. Mucocele in the anterior clinoid process is a rare cause of compressive optic neuropathy that can lead to monocular visual loss. A 19-year-old Sri Lankan girl presented with progressive, painless fluctuating right-sided monocular visual loss over 1-year duration. On presentation, right side visual acuity was 6/60 and fundoscopy revealed pale disk on the right side. Ocular tomography showed right-sided temporal retinal thinning. Magnetic resonance imaging revealed right anterior clinoid process mucocele causing compression and kinking of the right optic nerve. Because the right side, optic disc was already pale and retina was thinned, we decided to manage conservatively. Early imaging in compressive optic neuropathy is useful for the diagnosis and early neurosurgical intervention. Delaying the diagnosis can lead to permanent visual loss.