Anti-VEGF antibody injections result in sustained improvement in vision in diabetic macular edema

June 29, 2011

An anti-vascular endothelial growth factor (VEGF) antibody fragment given intraocularly significantly and rapidly improves vision in patients with diabetes and macular degeneration. The improvements are sustained up to 2 years, said David S Boyer, MD.

An anti-vascular endothelial growth factor (VEGF) antibody fragment given intraocularly significantly and rapidly improves vision in patients with diabetes and macular degeneration. The improvements are sustained up to 2 years, said David S Boyer, MD.
     Diabetic retinopathy is the most common microvascular complication of diabetes and increases with the duration of the illness. About 10% of patients with diabetes develop diabetic macular edema. Swelling in the central retina accounts for most vision loss in diabetic retinopathy. Unfortunately, 93% of patients with diabetic retinopathy and 63% with vision-threatening diabetic retinopathy are unaware they have any diabetic retinopathy, said Boyer, an ophthalmologist at Retina-Vitreous Associates in Beverly Hills, California.
     Laser photocoagulation has been the standard treatment for diabetic macular edema since 1985, but vision improvement after the procedure is uncommon, he said.
     In 2 double-masked, phase III trials, the anti-VEGF antibody fragment ranibizumab was studied in 366 patients with loss of vision (best corrected visual acuity 20/40 to 20/320 on a Snellen chart) and diabetic macular edema on retinal imaging. Approximately 70% of patients had received some form of prior therapy, usually laser photocoagulation. They were randomized to receive monthly ranibizumab (0.5 mg or 0.3 mg) or sham intraocular injections. Patients were eligible for rescue macular laser starting at month 3: 72% of sham-treatment patients and 33% of ranibizumab recipients received laser rescue.
     The mean duration of diabetes in the randomized groups was 14.5 to 16.6 years. Their mean hemoglobin A1c levels were 7.6% to 7.7%.
     The primary outcome-the proportion of patients gaining 15 or more standardized eye chart letters (≥3 lines) in best corrected visual acuity at month 24-was 18.1% in the sham-treatment group, 44.8% in the ranibizumab 0.3-mg group, and 39.2% in the ranibizumab 0.5-mg group in study 1; and 12.3%, 33.6%, and 45.7%, respectively, in study 2.
     “The vision improvement occurred as soon as week 1, seemed to go up in both groups after 6 or 7 months-6 or 7 injections-and then stabilized over the entire 24-month period,” said Boyer.
     The mean change in best visual acuity was +2.6 lines in the sham-treatment group, +12.5 lines in the ranibizumab 0.3-mg group, and +11.9 lines in the ranibizumab 0.5-mg group in study 1; and +2.3 lines, +10.9 lines, and +12.0 lines, respectively, in study 2.
     Some 54% to 62% of ranibizumab recipients achieved a Snellen acuity of 20/40 or better, compared with approximately one third receiving sham injections. An acuity of 20/40 or better is required in some states for driving privileges, he noted. Contrast sensitivity and retinal anatomy also improved significantly in the ranibizumab groups compared with the controls.
     Patient-reported function on the National Eye Institute Visual Function Questionnaire improved by 7 or more points (on a 1- to 100-scale) in the ranibizumab groups, which was significantly greater than the 4.0- to 4.4-point improvement in the sham injection group.
     One third of those receiving active therapy had 2 or more steps of improvement on the Retinopathy Severity Scale, compared with 7% of those receiving sham injections.