Challenging visual acuity measurement in a child with MOGAD syndrome: a case report

Case presentation: Female, 5 years old, admitted due to frequent falls associated with visual impairment and trouble identifying colors. The patient complained of worsening her visual acuity and bilateral blurriness. This symptom begun 14 months ago. Previous comorbidities and continuous medication use were denied. After an ophthalmological evaluation, bilateral vision loss was diagnosed. On physical examination, she presented isochoric and photoreactive pupils. Because the patient did not cooperate in measuring visual acuity, a subjective assessment was conducted. She was tasked with identifying toys, games, pictures on a monitor, and colors. The patient struggled to identify the items, suggesting a reduction in peripheral vision bilaterally. Muscle strength was preserved (grade V), without pathological plantar reflex. No alterations in balance, sensitivity, and coordination were diagnosed. Brain MRI disclosed gadolinium enhancement, without expansive characteristics, affecting the intracanalicular segment of the optic nerves and the intraorbital segment of the right optic nerve, suggesting bilateral optic neuritis (ON). Retinography showed bilateral papilledema. Thus, hospitalization was recommended to perform pulse therapy with Methylprednisolone (20 mg/kg/day for 5 days). Since then, she has been scheduled for Albendazole and pulse therapy, and tests were requested for anti-MOG (positive) and anti-aquaporin IV (non-reactive). After 10 days of hospital treatment, the patients visual acuity was reassessed, showing an improvement in her condition, except for color identification ability. She is followed up by neurology and undergoing rehabilitation for better color visualization. She is on Azathioprine and Prednisolone, as well as Paracetamol for intense headaches. She had unremarkable signs for autoimmune diseases. Discussion: We presented a case of a child with MOGAD, a recently recognized inflammatory demyelinating disorder of the central nervous system. The most common findings of MOGAD attacks are severe impairment on visual acuity with a good recovery after an early management. In this case, the patient presented with isolated bilateral ON, with almost complete improvement of visual impairments, despite challenging measurement of visual acuity. We used alternative visual skills to measure the visual acuity in a child with MOGAD optic neuritis. Final comments: The diagnosis of MOGAD is necessary for appropriate management to be established. However, the difficulty of clinically assessing visual acuity can hinder this early diagnosis.