Unilateral choroidal effusion secondary to carotid cavernous fistula

A man in his mid-70s presented to the eye clinic with sudden onset ptosis, bilateral ophthalmoplegia associated with eye pain and sluggish pupillary reaction. MRI of the head revealed cavernous sinus thrombosis. He was treated with warfarin and a regime of steroids which improved his ophthalmoplegia. Four months following his discharge, he developed a sudden reduction in visual acuity in his right eye; and a dilated fundal examination revealed choroidal effusion. He underwent further diagnostic imaging, and he was diagnosed with right carotid cavernous fistula (CCF). He was managed conservatively with steroids, and his fistula closed spontaneously. He eventually regained his visual acuity. Our case report highlights the challenge in diagnosing CCFs and how choroidal effusion facilitated the diagnosis.