Intravitreal Brolucizumab for Diabetic Macular Edema: Outcomes in Treatment-Naive and Anti-VEGF-Switched Eyes over 48 Weeks

Background: Brolucizumab has demonstrated efficacy for diabetic macular edema (DME) in pivotal clinical trials; however, comparative real-world data directly contrasting treatment-naive and anti-VEGF-switched eyes over a prolonged follow-up period remain limited. This case series evaluated 48-week functional, anatomical, and safety outcomes of intravitreal brolucizumab (IVBr) in treatment-naive and switched DME eyes in routine clinical practice. Methods: This retrospective, two-center case series included 21 eyes with center-involving DME treated with IVBr between May 2022 and April 2024. Eyes were classified into a treatment-naive group (n = 10), which included only eyes with no prior anti-VEGF treatment for DME, and a switched group (n = 11), which included eyes previously treated with other anti-VEGF agents but not achieving dry macula. Dry macula was defined as the absence of fovea-involving fluid on OCT. BCVA (logMAR), central retinal thickness (CRT), dry macula rate, the proportion of eyes gaining ≥2 lines of BCVA, number of injections, mean injection interval, and intraocular inflammation (IOI) were assessed at baseline and at 6, 12, 24, and 48 weeks. Results: At baseline, BCVA was 0.44 ± 0.27 in the treatment-naive group and 0.46 ± 0.28 in the switched group (p = 0.943), and CRT was 435.8 ± 150.1 μm and 461.8 ± 139.8 μm, respectively (p = 0.751). In the treatment-naive group, BCVA improved from 0.44 ± 0.27 to 0.24 ± 0.19 at week 48 (p = 0.023), and 5 eyes (50.0%) gained ≥2 lines. In the switched group, BCVA did not improve significantly (0.46 ± 0.28 to 0.41 ± 0.40; p = 0.461); 3 eyes (27.3%) gained ≥2 lines, and 1 eye (9.1%) lost ≥2 lines. CRT decreased significantly in treatment-naive eyes (435.8 ± 150.1 to 312.6 ± 106.2 μm, p = 0.020) and showed a non-significant reduction in switched eyes (461.8 ± 139.8 to 363.6 ± 127.4 μm, p = 0.067). Dry macula rates at week 48 were 40.0% and 27.3%, respectively (p = 0.659). Six switched eyes had prior intravitreal corticosteroid treatment for DME. One treatment-naive eye developed IOI, which resolved without permanent visual impairment. Conclusions: In this retrospective case series, IVBr was associated with anatomical improvement over 48 weeks, with clearer functional and anatomical responses in treatment-naive eyes than in switched eyes. However, the switched group was older and had a more heterogeneous treatment history, including prior intravitreal corticosteroid treatment. The findings should therefore be interpreted as exploratory.