Influence of Central Corneal Thickness Change on Intraocular Pressure Measurement after LASIK and LASEK

ABSTRACT

PURPOSE: To evaluate the influence of central corneal thickness change after LASIK and LASEK to intraocular pressure (IOP) measured by Goldmann applanation tonometer and noncontact tonometer. METHODS: The pre-and post-operative IOP, central corneal thickness were measured in the 94 eyes of 47 patients who underwent refractive surgeries (LASIK and LASEK) from November 2000 to November 2001. Central corneal thickness was measured by ultrasonic pachymeter. IOP was measured by Goldmann applanation and noncontact tonometer. RESULTS: Post-operative IOP after LASIK and LASEK was significantly lower than pre-operative IOP. IOP measured with the noncontact tonometer was higher than that with Goldmann applanation tonometer in the group with thick cornea (>500micro meter in thickness) and lower in the group with thin cornea (< 500micro meter in thickness). Positive relationship between corneal thickness and measured IOP was greater in noncontact tonometer than Goldmann applanation tonometer. In noncontact tonometer, the amount of decreased IOP of LASIK group was greater than that of LASEK group. CONCLUSIONS: There was a close relationship between central corneal thickness and IOP. Measured IOP may be influenced by surgical method and type of tonometer. These findings suggest that we should be cautious when evaluating the IOP of eyes which underwent excimer laser refractive surgery because the measured IOP can be lower than actual IOP.