Topiramate is primarily used as an antiepileptic drug. It has also demonstrated effectiveness in migraine prophylaxis, depression, trigeminal neuralgia, bipolar disorders, and idiopathic intracranial hypertension. The drug has a large number of potential ocular side effects, such as acute-onset angle closure glaucoma (ACG), acute myopia, nystagmus, diplopia, photosensitivity, suprachoroidal effusions, peri-orbital edema, and blepharospasm. Presently described is the case of a 24-year-old woman presenting with a sudden loss of vision in both eyes. Her medical history revealed that the patient had initiated topiramate use 12 days earlier. The uncorrected visual acuity was 20/400 in both eyes and the best corrected visual acuity was determined to be 20/25 in the right eye with -5.50 spherical refractive correction and 20/20 in the left eye with -6.25 spherical refractive correction. On the second day of examination, diplopia developed. The patient's clinical condition was considered to be related to the drug and topiramate was discontinued immediately. The clinical findings of the patient subsequently improved rapidly without treatment. On the fifth day of examination, her autorefractometry measurements were +0.25 -0.25 α 121° in her right eye and +0.25 in her left eye and her uncorrected visual acuity was 20/20 in both eyes with normal bilateral anterior chamber depth. She had no vision complaint or diplopia but she began to experience photosensitivity, which persisted for 4 months before regressing completely. When ophthalmologists encounter acute myopia and acute-onset ACG, especially in young patients, they should keep the use of topiramate in mind.