Postmarketing surveillance of corneal edema, Fuchs dystrophy, and amantadine use in the veterans health administration

Purpose: To determine the proportion of patients who were dispensed amantadine and diagnosed with corneal edema or Fuchs dystrophy within specified time frames. Methods: Postmarketing surveillance study. The national Veterans Health Administration pharmacy and clinical databases were used to identify a cohort of veterans without a prior history of corneal edema, Fuchs dystrophy, or a prescription for amantadine. During fiscal years 2005-2006, 2 databases were used to identify patients with new diagnoses of corneal disease and new prescriptions for amantadine. Patients from each were cross-referenced. The outcome measure was concurrent diagnosis of corneal edema or Fuchs dystrophy and new prescription for amantadine within specified intervals. Results: Thirty-six (0.27%) patients among the 13,137 who were dispensed amantadine were diagnosed with corneal edema or Fuchs dystrophy within the 2-year study period. The relative risk of corneal edema for a person prescribed amantadine was 1.7 (95% confidence interval: 1.1-2.8). In 12 (0.09%) patients, the corneal diagnoses were recorded within a month of being prescribed amantadine. Conclusions: Retrospective examination of a large national medical database revealed that amantadine was temporally associated with a small proportion of patients diagnosed with corneal edema or Fuchs dystrophy. Although additional studies are needed to confirm the risk of corneal edema with amantadine, the development of corneal edema in persons prescribed amantadine warrants clinical attention. In such a situation, physicians may consider stopping amantadine to see if the edema subsides.