Reliability of the IOLMaster in measuring corneal power changes after photorefractive keratectomy

PURPOSE: To test the accuracy of the IOLMaster (Carl Zeiss) in detecting corneal power changes after photorefractive keratectomy (PRK). SETTING: Department of Ophthalmology, 2nd University of Naples, Naples, Italy. METHODS: Two hundred twenty-five consecutive eyes that had PRK (mean -5.13 diopters D] +/- 2.98 SD] range +0.25 to -16.25 D]) were analyzed. The data included preoperative and postoperative (1, 3, and 6 months) subjective refraction and computerized keratometry. Statistical analysis was performed to determine the correlation between the changes in the subjective refraction at the corneal plane and the changes in keratometry. RESULTS: The mean difference between the changes in refraction and the measured corneal changes was 0.75 +/- 1.13 D (range -3.84 to +7.68 D) at 1 month, 0.92 +/- 1.10 D (range -0.87 to +7.93 D) at 3 months, and 0.75 +/- 0.98 D (range -1.70 to +3.85 D) at 6 months. The difference was significant (P<.001). CONCLUSION: Automated keratometry provided by the IOLMaster did not accurately reflect the effective refractive changes after PRK, particularly in eyes that had a high dioptric treatment.