ABSTRACT
Background : Acute zonal occult outer retinopathy (AZOOR) is a rare, recently introduced sectorial outer retinopathy commonly seen in young females. The presence of AZOOR in multiple sclerosis (MS) patients can sometimes masquerade as optic neuritis. We hereby analyze an infrequent case of such an incident, as well as the comorbidities of this particular patient and the arising differential diagnostic dilemmas. Case Presentation : A 29-year-old female MS patient on cladribine presented in the emergency department (ED) due to left eye (LE) visual disturbances which appeared after Covid-19 infection. As a result of her past medical history, the case was considered to be consistent with optic neuritis. The patient was treated with high doses of intravenous methylprednisolone, but despite the treatment symptoms persisted. Ophthalmological findings were compatible with AZOOR. Conclusions : AZOOR can coexist with MS. However, it is unclear whether cladribine treatment or Covid-19 infection triggered AZOOR. Given the potential for ocular adverse effects associated with cladribine use, patients should be encouraged to report visual disturbances promptly. In addition, medical professionals must be vigilant of MS patients on cladribine complaining of visual symptoms, and refer them to an ophthalmologist as soon as possible.