**4. Current standard method used for intraoperative corneal pachymetry measurements**

Currently, ultrasound pachymetry is the most commonly used method for intraoperative pachymetry measurements during CXL. However, pachymetry measurements using this technique are subject to limitations: only single point measurements can be obtained and it is necessary to have contact to obtain the measurements, thus making the results more prone to inter- and intra-observer variability. In addition, vulnerability to infections due to contact with the surface of the eye and inadequate sterilization of the ultrasound tip during the procedure is another concern associated with this method.
