We read with interest the paper by Wimpissinger et al, comparing the sutureless 23-gauge (23GA) system with a standard 20-gauge (20GA) system for pars plana vitrectomy, in a randomised clinical trial.1 We aim to highlight a few issues in the design, methodology and analysis.

The authors have analysed postoperative pain and conjunctival injection as primary outcome measures. The effort by the assessor to elicit a response on the degree of pain is likely to be biased if they are not masked, as in this study. …