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Retinal vascularization speed in retinopathy of prematurity

We read with great interest the article entitled ‘Retinal vascular speed <0.5 disc diameter per week as an early sign of retinopathy of prematurity requiring treatment’ by Solans Pérez de Larraya et al.1 In this study, the researchers reported that slower progression of the retinal vascularization is correlated with any retinopathy of prematurity (ROP) requiring treatment. We congratulate the authors for their study. However, we have some comments with regard to this publication. There seems to be a problem with the methodology of the study. As already expected, in the eyes of the infants developing any stage of ROP, the vascularization of the retina stagnates and the vascularization tends to aim towards the centre of the vitreous cavity.2 Hence, it is important to mention whether the measurement of retinal vascularization was obtained before the formation of the demarcation line and the ridge. Second, how was the analysis of vascular progression performed in a retrospective designed study? According to their methodology, a routine retinal examination was done. The measurements were obtained with clinical examination which was subjective even with referencing the optic disc diameter. The examination protocol defined for the present study has some flaws such as the measurement method, particularly in the anterior retina that needs scleral indentation to visualize it. Moreover, the frequency of follow-up examinations need to be specified as weekly, biweekly and so on. Finally, the main outcome measures for the study lacks, particularly in the eyes that need treatment. It is not clear whether they excluded patients who need laser or intravitreal injection treatment or not? The retinal vascularization speed measured in the eyes treated with laser or anti-VEGF needs to be described. We hope that our comments will be useful for further studies in this field.