EVALUATION OF THE EFFECT OF TOPICAL INTERFERON α2b AS A COMPLEMENTARY TREATMENT OF MACULAR EDEMA OF PATIENTS WITH DIABETIC RETINOPATHY: A Double-Blind Placebo-Controlled Randomized Clinical Trial Study.

Purpose: The objective of this study is to evaluate the effect of the topical interferon α2b (IFNα2b) as an adjunctive therapy in the treatment of diabetic macular edema.

Method: This was a randomized controlled clinical trial performed on patients with diabetic macular edema. Fifty eyes of 50 patients (one eye/patient) who were receiving treatment for diabetic macular edema were randomly assigned to get topical IFNα2b 1 MU/mL or artificial tear eye drop as an adjunctive therapy. The primary measure outcomes were best-corrected visual acuity and central macular thickness; the secondary goals were to assess the effect of topical IFNα2b on the intraocular pressure and its potential side effects.

Results: Baseline demographic data of the two groups were similar. The improvement in visual acuity of patients on IFN was more than the patients on artificial tear by the end of the fourth week (6.85 and 1.45 Early Treatment Diabetic Retinopathy Study letters, respectively, P = 0.001) and the eighth week (6.75 and 1.05 Early Treatment Diabetic Retinopathy Study letters, respectively, P = 0.005). The central macular thickness was also decreased correspondingly by the end of fourth week (53.1 ± 153 µm for patients on IFN and 26.6 ± 119.1 µm for patients on artificial tear, P = 0.497) and eighth week (27.9 ± 67.7 for patients on IFN and 29.2 ± 98 µm for patients on artificial tear, P = 0.957), but it was not statistically significant. Intraocular pressure was decreased on the fourth week in IFN group for 1.7 mmHg ±3 and increased for 0.1 mmHg ±2.3 in the artificial tear group (P = 0.018). No significant side effect was detected with topical IFN drop.

Conclusion: This study evaluated the short-term effects of topical IFNα2b 1 MU/mL. The drug was well tolerated and may have an effect on improvement of best-corrected visual acuity in patients with diabetic macular edema. It also had an intraocular pressure lowering effect on the studied eyes. However, further studies are needed to confirm this finding.