Sir,

We are grateful that Dan and Mihai Călugăru1 took interest in our article. The subject of optimal intensity of anti-VEGF treatment has been discussed previously following the publication of a similar claims data study, which described real-world treatment patterns of ranibizumab and aflibercept for macular oedema secondary to central retinal vein occlusion.2, 3, 4 Our study aimed to understand whether the frequency of ophthalmology visits for patients treated with ranibizumab (Lucentis) and dexamethasone implant (Ozurdex) differed in routine clinical practice in the United States for the treatment of macular oedema secondary to retinal vein occlusion (RVO).5 Comparing treatment frequency was a secondary objective in our study, with the resulting estimate of ranibizumab treatment frequency being consistent with that previously observed by Lotery and Regnier.2

We agree with Dan and Mihai Călugăru that the observed treatment patterns in our analysis should not be interpreted as the optimal treatment frequency. The frequency of treatment administration neither reflects the treatment frequency observed in clinical trials6, 7 nor provides data on visual acuity outcomes attained by the treated cohort. In our discussion, we outline the limitation that visual acuity data were not available in the claims database at our disposal for the conduct of this study.5

The Callanan et al. study aimed to demonstrate the non-inferiority of dexamethasone implant compared to ranibizumab with respect to mean average change from baseline best-corrected visual acuity (BCVA) over 12 months in patients with diabetic macular oedema. The primary outcome of non-inferiority between treatments was met; however, statistically significant and clinically meaningful differences were observed in mean change from baseline in BCVA favouring ranibizumab. Furthermore, a saw-tooth pattern in central retinal thickness (CRT), indicative of frequent fluctuation of CRT, was observed in the dexamethasone arm. This is in contrast to the sustained improvements in CRT for ranibizumab-treated eyes during the study period.8 Superiority of dexamethasone implant vs ranibizumab in anatomical outcomes was not demonstrated in the Callanan study. Moreover, the authors did not find the claim of superior anatomical outcomes associated with dexamethasone implant adequately supported by randomised clinical trial evidence.1

Studies linking treatment patterns to real-world clinical outcomes in RVO will be an important part of understanding outcomes attained by patients in routine clinical practice.