Siponimod-related bilateral cystoid macular oedema and intravenous fluorescein angiographic findings in a patient with stable proliferative diabetic retinopathy without history of diabetic macular oedema

Siponimod is a sphingosine-1-phosphate receptor modulator used as disease-modifying therapy for relapsing-remitting multiple sclerosis similar to Fingolimod which has been known to cause dose dependent fingolimod associated macular oedema (FAME). We report a case of delayed onset bilateral cystoid macular oedema in a patient with stable proliferative diabetic retinopathy who developed cystoid macular oedema in the setting of siponimod (Mayzent; Novartis Pharmaceuticals; Cambridge, Massachusetts, USA) use. As with FAME, cystoid macular oedema resolved in the patient's eyes with drug cessation and adjunctive topical anti-inflammatory therapy. We highlight unique fluorescein angiographic findings within this class of drugs as well as the clinical challenge posed by comorbid diabetic and inflammatory ophthalmic pathology.