Corneal power estimation for intraocular lens power calculation after corneal laser refractive surgery in Chinese eyes

PurposeTo develop and evaluate an algorithm for corneal power estimation in intraocular lens (IOL) power calculation after corneal laser refractive surgery in Chinese eyes.SettingGuangdong Eye Institute, Guangdong Academy of Medical Sciences, Guangzhou, China.DesignProspective comparative case series.MethodsCorneal parameters in Chinese eyes and German eyes were measured using a rotating Scheimpflug camera. Corneal power was simplified as a corrective algorithm: KC = 1.114 × KM + K2 (KM = measured K reading; K2 = KP − KA × KP × CT/1.376; KA = anterior corneal power; KP = posterior corneal power; CCT = central corneal thickness). The variation and change in K2 induced by refractive surgery were analyzed in Chinese eyes. The corrective algorithm was identified as KC = 1.114 × KM − 6.20. The method was evaluated in Chinese cataract cases after refractive surgery using the Haigis formula.ResultsNo difference in anterior corneal radius (RA) or CCT between Chinese eyes and German eyes were found; however, the posterior corneal radius (RP), RA/RP ratio, keratometric index, and K2 were different. The mean K2 was −6.23 diopters (D) ± 0.24 (SD) in Chinese eyes and −6.12 ± 0.23 D in German eyes (P<.01). The mean change in K2 induced by refractive surgery was −0.02 ± 0.06 D. The median absolute prediction error in IOL power calculation was 0.43 D (range 0.01 to 1.80 D).ConclusionThe algorithm was a relatively reliable method in IOL power calculation after corneal refractive surgery in Chinese eyes.Financial DisclosureNo author has a financial or proprietary interest in any material or method mentioned.