title: Practical method to calculate post-LASIK corneal power: the Actual K(a+p) method.
abstract: OBJECTIVE
  To evaluate the accuracy of a practical method (the Actual K(a+p) method) of corneal power measurement for post-LASIK eyes undergoing cataract surgery.
  
  
  METHODS
  Ten eyes of 7 patients (4 male, 3 female, average age 50.10±4.01 years, with -11.01±3.55D mean refraction before LASIK), underwent post-LASIK phaco+IOL cataract surgery. We used the posterior corneal curvature as measured by the Pentacam in a method we named Actual K(a+p) to calculate the post-LASIK corneal power for IOL calculation. The refractive outcomes after cataract surgery were evaluated. The Actual K(a+p) was compared with the back- calculated corneal power (BCK), which was thought to be the benchmark of true corneal power. The corneal power estimated by other published methods, including Maloney, Shammas, Koch-Maloney, Savini, and McCulley, together with the true net power and equivalent K reading (EKR) as found by the Pentacam were also compared with the BCK.
  
  
  RESULTS
  All eyes achieved satisfied refractive status after cataract surgery. The difference between the postoperative refraction and the target refraction was 0.04±0.40D, range from -0.63D and +0.85D. Among all the methods we studied, although the Bonferroni multiple comparison tests did not detect significant differences between any two of them, the Actual K(a+p) yielded the highest agreement with the BCK, with 80% of the eyes falling within ±0.5D and 100% within ±1.0D from the BCK values.
  
  
  CONCLUSIONS
  The Actual K(a+p) method can provide encour- aging results in post-LASIK eyes undergoing cataract surgery.
authors.affiliation: Department of Ophthalmology, Xinhua Hospital Affiliated to School of Medicine, Shanghai Jiaotong University, Shanghai 200092, China.
authors.forename: Yi-Qian
authors.initials: YQ
authors.lastname: Hu
authors.forename: Xiang-Yu
authors.initials: XY
authors.lastname: Ye
authors.forename: Xiu-Li
authors.initials: XL
authors.lastname: Zhou
authors.forename: Yin
authors.initials: Y
authors.lastname: Li
authors.forename: Cheng-Hui
authors.initials: CH
authors.lastname: Xu
authors.forename: Lin-Lu
authors.initials: LL
authors.lastname: Tian
authors.forename: Huang
authors.initials: H
authors.lastname: Zhu
authors.forename: Yao-Hua
authors.initials: YH
authors.lastname: Sheng