Purpose : Evaluation of efficacy of Memantine (N-Methyl-D-Aspartate Receptor Antagonist) on visual function of patients with acute non-arteritic ischemic optic neuropathy (NAION).

Methods : The study was conducted as interventional case series from November 2005 through November 2006 in Farabi Eye Hospital . Twenty-two patients with acute NAION of less than 8 weeks duration entered the study. Memantine was prescribed with a dose of 5 mg per day for the first week and 10 mg per day for the following two weeks. Baseline best corrected visual acuity (BCVA); visual evoked potential (VEP) and visual field was done for all patients. BCVA recording repeated 3 weeks, 3 and 6 months later. VEP and perimetry repeated 3 months after treatment.

Results : After 3 weeks, 3 and 6 months, BCVA improved -0.32±0.40 LogMAR, -0.51±0.49 and
-0.51±0.49, respectively (P=0.005, P=0.001 and P=0.001, respectively). VEP recordings after 3 months, demonstrated -8.61±14.51 db mean decrease in implicit time (P=0.019). Amplitude of voltage did not show significant difference with baseline (P=0.10). Perimetry results after 3 months showed that mean deviation (MD) improved 2.77± 3.94 db (P=0.016).

Conclusion : Memantine resulted in significant improvement of BCVA 3 weeks, 3 and 6 months after treatment of acute NAION. Memantine also resulted in significant decrease of implicit time and significant improvement of mean deviation in VEP and perimetry after 3 months.