Sir,
We would like to thank Călugăru and Călugăru1 for their comments on our paper, Central retinal vein occlusion: modifying current treatment protocols.
Although bevacizumab is widely used in common practice, there are no large-scale randomized control trials that have studied bevacizumab. Even the quoted paper1 had a relatively small cohort of 57 patients. It is difficult to extrapolate recommendations especially with regard to long-term outcomes until larger studies have been conducted.
Although the 2 mg ranibizumab dose in the Relate study2 did show a better anatomical response compared with the other doses, this was not mirrored in visual outcomes. In addition, with the absence of a commercially available 2.0 mg dose and in the context of a visual acuity guided strategy, it would be difficult to advocate quadrupling the dose of ranibizumab.
There have been no large studies that have looked into treat and extend for treating CRVO. However, we did not advocate this particular strategy. We proposed gradually extending the follow-up periods based on the data from HORIZON, which showed that in the second year patients followed up every 3 months post vision.3 Hence with regard to certain patients following them closely would allow identification of early recurrences. Furthermore, we believe that the mandatory treatments during extension cycles typically reserved for age-related macular degeneration (AMD) is unnecessary in CRVO. In AMD, each recurrence is associated with a drop in final visual acuity as evidenced by a difference in final visual outcomes between monthly and PRN dosing regimens.4 In diabetic macular edema and in CRVO, the pathology is quite different and as evidenced by the SHORE study, there is no difference between the patients treated using a PRN regimen and maximum monthly dose regimen.5 Hence with regard to the treatment, PRN would seem to be the ‘better’ dosing option, and the standard Treat and extend would overtreat a significant number of patients.
The data from Călugăru and Călugăru1 regarding the use of bevacizumab in cases of ischemic CRVO included 21 patients with ischemic CRVO/HRVO. These data are important, however, was not included because of the relatively small number. It would be interesting to study the effects of bevacizumab in ischemic CRVO on a larger scale.
Switching to aflibercept,6 although still a relatively novel approach to treating resistant CRVO, has been gaining significant traction in real-world practice. It is a more appealing option than using steroids and there are mounting data that it might be a good option.7, 8 However, this has yet to be confirmed with larger studies conducted in a prospective manner.
Finally, we appreciate the in-depth analysis and the debate with regard to treating CRVO, and we acknowledge that this is a serious disease that requires aggressive and timely intervention to preserve vision.
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Ashraf, M., Souka, A. & Singh, R. Response to: ‘Comment on Central retinal vein occlusion: modifying current treatment protocols’. Eye 30, 1396–1397 (2016). https://doi.org/10.1038/eye.2016.84
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DOI: https://doi.org/10.1038/eye.2016.84