| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4018346 | Journal of Cataract & Refractive Surgery | 2013 | 6 Pages |
PurposeTo establish a corneal correction equation for the Shammas post-hyperopic laser in situ keratomileusis (LASIK) (Shammas-PHL) formula and to evaluate its accuracy in cases with and without available pre-LASIK data.SettingPrivate practices, Lynwood, California, and Mesa, Arizona, USA.DesignRetrospective comparative observational study.MethodsThe corrected corneal power (Kc) was calculated in each eye by adding the refractive change at the corneal level to the pre-LASIK keratometric (K) readings. By comparing Kc with the measured post-LASIK K readings (Kpost), the following equation was derived: Kc = 1.0457 Kpost−1.9538. This equation was combined with the Shammas original formula to obtain the Shammas-PHL formula.ResultsThe new formula was evaluated in 18 eyes with previous LASIK data and in 24 eyes with no previous LASIK data. Using the Shammas-PHL formula, the mean arithmetic prediction error was −0.03 diopter (D) ± 0.72 (SD) (range −1.57 to +1.54 D) and the median absolute error was 0.38 D in 18 eyes with available pre-LASIK data and 0.05 ± 0.58 D (range −0.56 to +1.40 D) and 0.43 D, respectively, in the 24 eyes with no pre-LASIK data.ConclusionThe Shammas-PHL formula can be used in post-hyperopic LASIK cases whether or not the pre-LASIK data are available.Financial DisclosureNo author has a financial or proprietary interest in any material or method mentioned.
