Taking femtosecond surgery as an example, although the operation process is very short, only a few minutes, preoperative examination is essential. A strict professional preoperative examination usually takes about 2 hours, which requires more than 20 detailed and in-depth examinations such as naked eye vision, wearing glasses vision, intraocular pressure and corneal topography. For the core key data, it needs to be measured many times and compared repeatedly to ensure the parameters are correct.