Objective: To evaluate how the change of thickness or curving of the cornea after refraction operations (PRK or LASIK) influences the intraocular pressure (IOP) during assessment with a noncontact tonometer. Place of investigation: Ophthalmological Clinic SPAM and Ophthalmological ambulance EXCIMER. Material and methods: With regard to the performed refraction operation the patientswere dividedintotwogroups.Thefirstgroupcomprised87patientswhere PRK was performed to correct myopia. The mean myopia in this group was -5.27 D ± 2.32. The second group comprised 62 patients where LASIK surgery was performed to correct myopia. The mean myopia in this group was -10.18 ± 4.36. IOP was assessed by means of a noncontact tonometer before and 6 months after surgery. Results. In the first group a mean reduction of IOP by 4.8±2.1 mm Hg occurred. The central thickness of the cornea declined on average by 55.69 ±28.9 micros and the curving of the cornea diminished on average by 3.72 D ± 1.76 D. In the second group of patients the IOP declined on average by 7.97 ± 2.04 mmHg. The central thickness of the cornea diminished by 78.75 microns ± 42.26 and the curving of the cornea by 4.65D ± 2.07In both groups a significant correlation was found between the reduction of IOP and the central thickness and curving of the cornea. Conclusion: Diminution of the thickness of the central cornea and diminution of the curving lead to lower values of the IOP. There is a direct correlation between thinning of the cornea and the decline of IOP.

        Key words: intraocular pressure, refraction operation, accuracy of assessment