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Modified corneal measurement most accurate after LASIK
HOUSTON — The most accurate method to determine postoperative corneal refractive power after LASIK is to adjust corneal measurements based on the amount of refractive change induced by the surgery, according to a study.
Researchers here compared five methods of measuring the cornea to determine the most accurate way of measuring corneal refractive power after LASIK. They evaluated 100 eyes of 63 patients using computerized videokeratography, keratometry, the Gaussian optics formula and values of the videokeratography and keratometry as modified according to the amount of LASIK-induced refractive change. They compared all these measurements using the patient’s clinical history refraction as the standard.
Postoperative computerized videokeratography and keratometry values were higher than clinical history results, and Gaussian results were lower. The differences between the clinical history results and both postop videokeratography and keratometry values increased significantly, proportionally to the amount of myopic correction. The most accurate results were found by modifying the postop values of the videokeratography according to the amount of LASIK-induced change. In these results, 70% of the values were within 0.5 D and 94% were within 1 D of clinical history results.
The study is published in the April issue of Ophthalmology.