Amantadine-induced corneal edema: A case and literature review

PURPOSE: To present a case of irreversible corneal edema after 10 years of amantadine use. A literature review was carried out to describe the clinical characteristics and outcomes of amantadine-induced corneal edema. OBSERVATIONS: A 36-year-old woman presented with a 6-week history of gradually progressive bilateral painless visual loss with visual acuity (VA) of 20/350 and 20/300 in the right and left eye, respectively. Examination showed bilateral diffuse central corneal edema with multiple Descemet membrane folds without endothelial guttata, keratic precipitates or intraocular inflammation. This did not respond to hypertonic saline drops and empirical treatment for presumed herpetic endotheliitis with oral acyclovir. Medication review revealed the use of amantadine 100mg daily for the past 10 years, prescribed by her neurologist for fatigue. Despite discontinuing amantadine, corneal edema was irreversible due to a markedly reduced endothelial cell count of 625 (right) and 680 cells/mm(2) (left). CONCLUSIONS AND IMPORTANCE: This case highlights the need to consider amantadine as a cause of unexplained bilateral non-guttae corneal edema. A literature review of 33 case reports revealed broadly similar features of amantadine-induced corneal edema; whilst most cases had favorable outcomes with median VA 20/25 (interquartile range IQR 20/20–20/30) and complete resolution of corneal edema within 30 days (IQR 14–35) of amantadine discontinuation, most experienced low endothelial cell density 759 cells/mm(2) (IQR 621–1078). Taken together, screening specular microscopy ought to be considered for those in whom amantadine is likely required long-term.