Keratometry and Computerized Videokeratography in Determining Intraocular Lens Calculation.

Kim, Song Hak; Myong, Yoon Won

Original Article

Journal of the Korean Ophthalmological Society 1998;39(6):1159-1164.
Published online June 1, 1998.

Keratometry and Computerized Videokeratography in Determining Intraocular Lens Calculation.

Song Hak Kim, Yoon Won Myong

Department of Ophthalmology, College of Medicine, St. Mary`s Hospital, The Catholic University, Seoul, Korea.

인공수정체 돗수 측정에 있어 각막 만곡계와 Computerized Videokeratography 의 비교

김송학(Song Hak Kim),명윤원(Yoon Won Myong)

Abstract

The most important factor in intraocular lens power calculation is the axial length, followed by the corneal power measurement. In measuring corneal power, conventionally used keratometry evaluates only four indivisual points on the central 3mm of the corneal surface. But coinputerized videokeratography (CVK) is a new technology which maps inside and outside of the central 3mm zone using twenty or seventy hundred data maps. We studied 27 eyes of 26 patients having phacoemulsification and posterior chamber lens implantation. We calculated corneal power using keratometry and CVK. Using the SRK II and Holladay, we obtained intraocular lens power with keratometric value and five values derived. from CVK. 6 weeks later, we evaluated actual postoperative refractive errors and predictive values for each pararneters. Keratometric datas were lower than CVK datas in mean absolute error and standard deviation between actual and predicted postoperative refractive errors and were higher in percentages of cases with power prediction errors < OR =l.0, < OR =2.0 and < OR =3.0 diopters for each formula. And the average keratornetric datas were 0.25mm flatter than CVK. Conventional keratometry may provide more accurate corneal curvature value than the CVK in intraocular lens power calculation.

Key Words: Computerized videokeratography;Keratometry;Intraocular lens power