Objectives: The aim of the study was to determine the influence of the main corneal incision on postoperative astigmatism. The following parameters were observed during the study: visual acuity without correction before and after surgery, spherical equivalent, corneal topography, number of corneal endothelial cells, additional diagnoses of patients, subjective impression of surgical knife quality and knife resterilization. Materials and methods: The research was conducted at the Clinic for Ophthalmology, Clinical Hospital Center Split. 23 patients were included. The time spent collecting data was 6 months (January 2021 - July 2021) During and after the survey, the rights and personal data of respondents are protected in accordance with the Patients' Rights Protection Act (OG 169/04, 37/08) and the protection of personal data (OG 103 / 03-106 / 12), and the research is harmonized with the provisions of the Code of Medical Ethics and Deontology (OG 55/08, 139/15) and the rules of the Declaration of Helsinki (1964-2013). For the implementation of the research, the approval of the Ethics Committee of the Clinical Hospital Center in Split under number 2181-147 / 01/06 / M.S.-20-02 was requested and obtained. Patients were examined by an ophthalmologist. Visual acuity (SC, CC, spherical equivalent), intraocular pressure by applanation Goldmann tonometry, fundus in mydriasis with a superfield non-contact lens and biomicroscopic examination of the anterior segment of the eye were recorded. Results: Of the 23 patients included in this study, 10 (43.48%) were men and 13 (56.52%) were women. The median age of the respondents was 73 (56-88). Visual acuity after surgery is significantly better. Postoperative astigmatism is statistically significantly lower than preoperative astigmatism. No statistically significant difference was shown when using a resterilized and a new knife. There is a negative correlation between preoperative astigmatism and postoperative astigmatism. Conclusions: Visual acuity improved after surgery. An incision size of 2.2 millimeters has a beneficial effect on postoperative astigmatism. A comparison of the cylinder axis on the autokeratorefractometer and the Pentacam found a difference in values, but did not prove statistically significant. Postoperative astigmatism is statistically significantly lower than preoperative astigmatism. We found no statistically significant difference in the induction of postoperative astigmatism in patients operated with resterilized and non-sterilized disposable microkeratomas. We showed a positive correlation of postoperative change in astigmatism, however it is not statistically significant. There is a negative correlation between preoperative astigmatism and postoperative astigmatism.