Purpose: To assess the efficacy of ranibizumab for persistent diabetic macular edema (DME) previously treated with bevacizumab and compare monthly vs treat-and-extend (TAE) dosing.
Design: 12-month, open-label, prospective randomized comparative dosing study.
Participants: 27 participants with persistent foveal-involving DME recently treated with bevacizumab.
Methods: All subjects were to receive three initial monthly 0.3 mg ranibizumab injections before randomization to monthly (n=15) or TAE (n=12) injection protocols over 12 months. Treatment interval was extended by two weeks up to a maximum interval of 12 weeks in the TAE group if central subfield thickness (CST) was ≤ 300 μm or complete absence of intraretinal or subretinal fluid on the macular cube was observed. Follow-up interval was decreased by 2 weeks if CST increased above 300 μm with associated intraretinal and/or subretinal fluid.
Main outcome measures: Change in Early Treatment of Diabetic Retinopathy Study (ETDRS) best corrected visual acuity (BCVA), CST, adverse events.
Results: Prior to study enrollment, subjects received an average of 8.6 bevacizumab injections. At month 12, mean ETDRS BCVA improved by + 5.3 letters (p<0.05) and mean CST decreased by -99.6 μm (p<0.01) in all patients. At study exit, 18.5 % of subjects gained ≥ 3 lines of vision and 3.7% of subjects lost ≥ 3 lines. Patients treated via the TAE protocol gained +8.4 letters and decreased CST by -120.2 μm whereas those treated by monthly injection gained +2.7 letters and decreased CST by -83.1 μm at month 12.
Conclusions: Following conversion to ranibizumab in eyes with persistent DME refractory to bevacizumab, significant functional and anatomic improvements were noted. Visual and anatomical outcomes were similar in TAE and monthly treatment protocols.