Background/aims: Bevacizumab has been shown to be an effective treatment of macular oedema. This study assesses the response of macular oedema to bevacizumab with specific focus on the first 24 h postinjection.
Methods: Subjects with diabetic macular oedema (DMO) or exudative age-related macular degeneration (ARMD) received intravitreal bevacizumab injections. Early Treatment of Diabetic Retinopathy Study (ETDRS) visual acuity and OCT macular thickness measurements were obtained at baseline, 1, 3, 6, 24 and 48 h, 1 week and 1 month postinjection.
Results: The average baseline OCT was 452.91 microm (SD 182.96, range 249.00 to 784.00). After injection, there was a statistically significant decrease in OCT thickness within 2 h with a plateau phase out to 24 h, followed by a significant drop between 24 and 48 h, and a return towards baseline between 1 week and 1 month. Average changes in ETDRS visual acuity were not statistically significant, though many patients experienced a positive outcome.
Conclusion: While there is an immediate pressure-related effect, it appears that the anti-VEGF effects of bevacizumab require approximately 24 h to become active and persist for 2-3 weeks. These results suggest that injections at 2-3-week intervals might provide improved clinical outcomes, compared with the currently typical 4-6-week interval of injections.