Purpose : To evaluate the therapeutic effect of posterior sub-tenon methyl prednisolone in anterior ischemic optic neuropathy, No class 1 study has shown any conclusive medical or surgical treatment for non-arteritic anterior ischemic optic neuropathy (NAION). Efficacy of systemic or intravitreal steroids was suggested by some studies. This study was performed to evaluate the efficacy and safety of posterior sub-tenon injection of methyl prednisolone in eyes with acute NAION.

Methods : In a double blind randomized clinical trial, forty patients with a recent onset NAION were randomly assigned into case and control groups. The case group received a single posterior sub-tenon injection of 40 mg methyl prednisolone the control group received a sham injection. The patients had complete eye examination including visual field measurement and fluorescein angiography and systemic evaluation at the beginning. Eye examination was repeated at 2, 4, 6 and 8 week steps of the follow-up. Visual field was rechecked at the end of the follow-up. Statistical analysis used: SPSS 11.5 system, paired sample t-test independent sample t-test, χ² , and ANOVA.

Results : Visual acuity (VA) improved 0.3 logMAR (three lines of Snellen chart) in the case group (P<0.030), no visual improvement was observed in the control group (P<0.589). Comparison between the two groups showed improvement in VA (P=0.021 at two weeks, and P=0.053 at 8 weeks), visual field pattern standard deviation (PSD), (P=0.034) and optic disc edema, (P=0.000) in the treatment group. No case of globe perforation or severe intraocular pressure (IOP) rise was detected.

Conclusion : Posterior sub-tenon injection of methyl prednisolone was preferred to observation in acute NAION.