Background Acute or rapidly progressive visual impairment in children is a medical emergency which needs early recognition and optimal management strategies. Among the different causes of acute visual impairment in children, optic neuritis (ON) is an acquired disorder of the optic nerve due to inflammation, demyelination or degeneration and it is treatable. It may also represent a sentinel attack or relapse of a chronic demyelinating disorder such as multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein (MOG) antibody associated diseases.

Objectives This is to report a case series of three children presenting with acute visual impairment due to optic neuritis.

Methods This is a retrospective, descriptive case series by reviewing medical records of initial admission and follow-up.

Results Three patients were included in this case series.

Case 1: a 6-year-old girl suffered from acute visual impairment which was started on the right side and then involved bilaterally. Other systemic and neurological examinations were normal. Visual acuity was just perception of light on both eyes. She had a previous episode of acute disseminated encephalomyelitis (ADEM) 4 months ago. Investigations revealed positive MOG-IgG with negative anti-aquaporin 4 (AQP4) antibodies. MRI brain showed T2 hyperintense lesions with contrast enhancement of bilateral optic nerves. She was diagnosed as MOG-optic neuritis. Her vision fully recovered with intravenous methylprednisolone and immunoglobulin.

Case 2: a 10-year-old girl presented with a relapsing bilateral optic neuritis. At the first presentation, her visual acuity was perception to light only on both eyes. Anti-aquaporin 4 antibody was positive and bilateral optic nerves enlargement with contrast enhancement was seen in MRI brain. Her vision almost fully recovered with intravenous methylprednisolone. She had relapsed with acute visual impairment, intractable hiccups and vomiting, 3 months later. She was diagnosed as bilateral optic neuritis with area postrema syndrome; therefore, the second cycle of intravenous methylprednisolone was started again together with mycophenolate mofetil for long-term immunosuppression. However, her vision only partially recovered with visual acuity 6/20 on the right side and 6/60 on the left.

Case 3: a 7.5-year-old boy presented with acute onset of bilateral visual impairment with sensory impairment below T4 level. His blood inflammatory markers were normal and anti-aquaporin 4 and anti-MOG antibodies were also negative. Features of bilateral optic neuritis and transverse myelitis in spinal cord from C4 to T5 were seen in MRI studies. The diagnosis was NMOSD with negative AQP4-IgG. His vision also fully recovered after receiving intravenous methylprednisolone therapy.

Conclusions Optic neuritis should always be considered in children with acute visual impairment. Complete neurological and ophthalmological examinations are essential features of the clinical evaluation. Ophthalmology referral is required. Magnetic resonance imaging (MRI) study of the brain and orbits with gadolinium contrast provides confirmation of the diagnosis and underlying causes in most cases. Other tests including lumbar puncture, antibody testing for MOG and AQP4 antibodies are also recommended. Accurate and early diagnosis of optic neuritis is crucial as prompt aggressive treatment may result in a good prognosis on vision and mitigation of long-term disability.