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

摘要

Purpose: To develop and evaluate an algorithm for corneal power estimation in intraocular lens (IOL) power calculation after corneal laser refractive surgery in Chinese eyes. Setting: Guangdong Eye Institute, Guangdong Academy of Medical Sciences, Guangzhou, China. Design: Prospective comparative case series. Methods: Corneal parameters in Chinese eyes and German eyes were measured using a rotating Scheimpflug camera. Corneal power was simplified as a corrective algorithm: K C = 1.114 × K M + K 2 (K M = measured K reading; K 2 = K P - K A × K P × CT/1.376; K A = anterior corneal power; K P = posterior corneal power; CCT = central corneal thickness). The variation and change in K 2 induced by refractive surgery were analyzed in Chinese eyes. The corrective algorithm was identified as K C = 1.114 × K M - 6.20. The method was evaluated in Chinese cataract cases after refractive surgery using the Haigis formula. Results: No difference in anterior corneal radius (R A) or CCT between Chinese eyes and German eyes were found; however, the posterior corneal radius (R P), R A/R P ratio, keratometric index, and K 2 were different. The mean K 2 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 K 2 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). Conclusion: The algorithm was a relatively reliable method in IOL power calculation after corneal refractive surgery in Chinese eyes. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.