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.