Optic neuritis probably induced by isotretinoin.

Isotretinoin is a drug indicated in dermatology for the treatment of acne and used off-label for other skin and mucosal disorders. Most patients treated with isotretinoin develop mild adverse effects that do not affect the course of treatment. However, it can have less common unpredictable effects that are more serious and must be known by those who habitually use this drug in clinical practice. A 16-year-old girl weighing 63 kg with no relevant past medical history or treatment for chronic disease was evaluated in our department for moderate, predominantly facial juvenile acne that had not been controlled with topical treatment (adapalene and benzoyl peroxide in combination) or oral antibiotics (oral doxycycline 50mg for 2 months, interrupted 2 months before she started treatment with oral retinoids). Three months after starting treatment with oral isotretinoin (30mg daily, 0.47mg/kg/d), the patient began to notice vision loss and blurred vision in her right eye. She did not report pain with eye movements, impaired color vision, photophobia, or headache. The patient was evaluated by an ophthalmologist, who detected a peripheral visual field deficit in the right eye and established the clinical diagnosis of retrobulbar optic neuritis. Slit lamp examination and funduscopy showed normal findings in both eyes. The intraocular pressure was within the normal range in both eyes. On suspicion of an adverse reaction to isotretinoin, the patient was referred urgently to our clinic; when she attended she had reduced the daily dose from 30 to 20mg and her vision had improved considerably. At that time it was decided to stop treatment. Nuclear magnetic resonance imaging was requested to rule out demyelinating disease and the patient was referred to the neurology department. The general neurological examination was normal. A lumbar puncture revealed no pathological findings. The visual evoked potential responses revealed P100 waves with prolonged latency, decreased amplitude, and altered morphology and confirmed the pres-