Anterior Clinoid Process Mucocele: A Case Presenting with Sudden Vision Loss

Background: Mucoceles are benign encapsulated lesions filled with mucus located in parasinus cavities. The occurrence rate of the anterior clinoid process is varying significantly in different studies. Visual disturbances, diplopia, and retrobulbar pain are among the common manifestations of anterior clinoid process mucocele. To our knowledge, 17 cases of Anterior clinoid process mucocele with visual involvements have previously been reported. Aim: We aim to report a rare case of a middle-aged man with a large sphenoid mucocele admitted due to the loss of vision in his left eye. Case presentation: A 46-year-old man with a sudden vision loss in his left eye was admitted to Loghman Hakim Hospital. In physical examination positive relative afferent pupillary defect (RAPD) was evident. The visual acuity of his right eye was normal, while his left eye had no light perception. Moreover, his visual field was normal on the right side. He had no other medical complaints. Conclusion: Clinoid mucoceles causing cranial neuropathy are extremely rare. The proper diagnosis and prompt treatment are necessary to avoid permanent complications. With proper surgical intervention, recurrence of the mucoceles can be avoided.