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Measuring corneal power for intraocular lens power calculation after refractive surgery. Comparison of methods
Jin Hyung Kim1, D o-Hyung Lee, Choun K i Joo
1Department of Ophthalmology, Kangnam St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, South Korea.
Purpose:
To find a more accurate and predictable method for intraocular lens (IOL) power calculation in eyes after refractive surgery.
Setting:
Department of Ophthalmology, Kangnam St. Mary's Hospital, Seoul, Korea.
Methods:
The accuracy of the following methods for calculating IOL power in 132 eyes after PRK or LASIK was compared: manual keratometry, hard contact lens, refraction-derived keratometry at the corneal plane, and the refraction-derived keratometry at the spectacle plane. Based on this comparison, the IOL power was calculated in the 2 eyes of a patient using refraction-derived keratometry at the spectacle plane with the SRK II formula. Cataract surgery with IOL implantation was then performed.
Results:
The largest corneal power values were obtained using a manual keratometer and the smallest using refraction-derived keratometry at the spectacle plane (P <.001). In the patient having cataract surgery with IOL implantation, near target refraction was achieved with minimal error in IOL power.
Conclusions:
If the corneal power is known before refractive surgery, the use of the smallest value of those obtained using refraction-derived keratometry and the hard contact lens method is recommended. However, if the corneal power before refractive surgery is unknown, the use of the hard contact lens method is recommended.
