Aim: The aim of the study was to examine possible changes in eye axial length before and after ultrasound phacoemulsification cataract surgery and if one exists, another aim of the study was to detect in which way and how much it affected the best corrected visual acuity of the patient. Study type: Prospective cohort study. Patients and methods: The study included 30 adults of both gender who successively underwent ultrasound phacoemulsification cataract surgery and who consented to the study. Exclusion criteria were irregular astigmatism, previous corneal keratoplasty procedure, previous refractive eye surgery, corneal disease and keratoconus. Keratorefractometry, the best corrected visual acuity, and residual refraction as well as axial eye length ultrasound measurement were performed on every patient on day of surgery and one month after intraocular lens implantation. Differences in measured variables before and after cataract surgery were analyzed. Ultrasound aplanation biometry and eye axial length measurement were performed on the Nidek US - 4000 ultrasonic biometric device. All ultrasound phacoemulsification cataract surgeries were performed on the Infinity device by the same surgeon. Results: Out of 30 patients who underwent cataract surgery, 7 patients had a change in eye axial length. The differences in their eye axial lengths were not significant comparing to the 23 patients who did not have such a change in their eye axial length. The best corrected visual acuity before and after cataract surgery was without significant difference between the two groups of patients considering whether the eye axial length changed or not. The median of cumulative ultrasound energy input in the eye was significantly lower in subjects with an eye axial length change compared to those who had no confirmed change. Conclusion: The change in eye axial length was not significant compared to the 23 patients who did not have such a change. Patients with an altered eye axial length had no major change in refraction because the axial length alteration was small.