Sir,

We read the article by Codenotti et al1 with interest; however, we believe that the results may be partly biased because of the study design, and some important limitations should be discussed. Firstly, only 8 out of the 13 recruited patients underwent intravitreal autologous plasmin enzyme (APE). It seems clear that a sample size that is too small may produce inconclusive results. Likewise, despite the small sample of patients and without applying any normality test, the authors used the one-way analysis of variance instead of using a non-parametric method such as Kruskal–Wallis test in order to compare the means of BCVA, macular thickness, and macular sensitivity during follow-up. A further limitation is the lack of a control group, which in this case might have a crucial role in the interpretation of the results. Moreover, the unmasked, too subjective evaluation of posterior hyaloid peeling, judged as ‘difficult’, ‘easy’ or ‘very easy’, may not be accurate. Although it is true that this is the first study investigating intravitreal injection of APE in eyes affected by focal vitreomacular traction (VMT), the authors could have compared their results with the MIVI-IIT trial,2 in which a nonsurgical resolution of VMT was obtained in up to 44% of included patients, and with other studies that used intravitreal APE, for example, in diabetic macular edema associated with VMT,3 and macular epiretinal membranes and VMT syndrome.4

Finally, the study deals with an important contradiction. In the conclusion, it is suggested that ‘a single intravitreal APE injection seems to be insufficient to induce a complete PVD in patients affected by focal VMT syndrome’, whereas in the summary and according to the authors, ‘what the study adds is that intraocular APE appears to be a useful tool in vitreoretinal surgery by obtaining an easier-to-peel posterior hyaloids—a high rate of spontaneous resolution of VMT may occur’. This point should also be clarified.