Intraocular lens power calculation for eyes with high and low average keratometry readings: Comparison between various formulas. Issue 9 (September 2017)

• Record Type: Journal Article
• Authors: Reitblat, Olga; Levy, Adi; Kleinmann, Guy; Lerman, Tsahi T.; Assia, Ehud I.
• Is Part Of: Journal of cataract and refractive surgery. Volume 43:Issue 9(2017)
• Publication Date: 2017-09
• Subjects: 617.7
• DOI: 10.1016/j.jcrs.2017.06.036
• Languages: English
• ISSNs: 0886-3350

Abstract

Abstract : Purpose : To compare the accuracy of intraocular lens power prediction for eyes with average keratometry (K) readings greater than 46.00 diopters (D) and lower than 42.00 D. Setting : Ein‐Tal Eye Center, Tel‐Aviv, Israel. Design : Retrospective case series. Methods : Eyes having cataract extraction surgery with steep and flat preoperative corneal curvatures determined with the Lenstar‐LS900 device were enrolled. Refractive prediction errors for the Barrett Universal II, Haigis, Hill‐RBF, Hoffer‐Q, Holladay 1, Holladay 2, Olsen, and SRK/T formulas were compared. Optimized K values for the SRK/T formula were back‐calculated for each group. Validation was performed using an additional dataset. Results : The study comprised 171 eyes (79, K reading >46.00 D; 92, K reading <42.00 D). For K readings greater than 46.00 D, myopic errors were noted using the SRK/T and Hill‐RBF formulas and hyperopic errors using the Olsen C‐constant and Haigis (−0.31 D, −0.17 D, 0.18 D, and 0.17 D, respectively). The percentage of eyes with an absolute error within ±0.50 D from target refraction ranged from 60.8% (SRK/T) to 83.0% (Hill‐RBF). For K readings lower than 42.00 D, myopic errors were seen using the Haigis, Hill‐RBF, Hoffer‐Q, and Olsen‐C formulas (−0.31 D, −0.14 D, −0.22 D, and −0.17 D, respectively) and a hyperopic error using the SRK/T formula (0.16 D). The refractive prediction within ±0.50 D ranged between 75.0% (Haigis) and 96.7% (Barrett Universal II). Conclusions : Power calculation for eyes with flat corneas and steep corneas requires the use of specific formulas for accurate postoperative results. An adjustment method of the SRK/T formula is proposed.