A 40-year-old male patient with past medical history of chronic neck pain and stiffness presented to Southampton Eye Unit with sudden painless reduction of vision in his left eye (OS). At presentation, his visual acuity (VA) was 6/6 in the right eye (OD) and 6/60 Snellen OS.

The patient denied any past history of trauma. Past medical history was remarkable for chronic neck pain and stiffness, for which the patient used to take over-the-counter ibuprofen. From the patient’s drug history, it was revealed that the patient used to take Tolperisone (Mydocalm®) regularly, a centrally-acting muscle relaxant to help alleviate his chronic neck issue. He stopped ibuprofen before starting Tolperisone. He reported that he had been taking Tolperisone tablets 150 mg/day for the last month (he skipped some days) before presentation. One week before presentation, he stopped taking Tolperisone, as he had noticed a mild visual obscuration. One week later, he reported sudden painless central visual loss in the left eye. No other pertinent medical or family history was observed. Of note, he also reported no history of strenuous activities forcing him to breathe with a closed glottis.