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Eye Vis (Lond). 2018 Jul 8;5:18. doi: 10.1186/s40662-018-0110-5. eCollection 2018.

Intraocular lens power calculation in eyes with previous corneal refractive surgery.

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1G.B. Bietti Eye Foundation, Rome, Italy.
2Stein Eye Institute, University of California, Los Angeles, CA USA.
St. Mary's Eye Center, Santa Monica, CA USA.



This review aims to explain the reasons why intraocular lens (IOL) power calculation is challenging in eyes with previous corneal refractive surgery and what solutions are currently available to obtain more accurate results.


After IOL implantation in eyes with previous LASIK, PRK or RK, a refractive surprise can occur because i) the altered ratio between the anterior and posterior corneal surface makes the keratometric index invalid; ii) the corneal curvature radius is measured out of the optical zone; and iii) the effective lens position is erroneously predicted if such a prediction is based on the post-refractive surgery corneal curvature. Different methods are currently available to obtain the best refractive outcomes in these eyes, even when the perioperative data (i.e. preoperative corneal power and surgically induced refractive change) are not known. In this review, we describe the most accurate methods based on our clinical studies.


IOL power calculation after myopic corneal refractive surgery can be calculated with a variety of methods that lead to relatively accurate outcomes, with 60 to 70% of eyes showing a prediction error within 0.50 diopters.


Cataract; Corneal surgery; Excimer laser; Intraocular lens power; Keratometry; LASIK; PRK

Conflict of interest statement

The study was approved by the Ethics Committee of G.B. Bietti Foundation IRCCS, Rome, Italy.Not applicable.KJH licenses the registered trademark name Hoffer® to ensure accurate programming of his formulas to Carl Zeiss-Meditec (IOLMasters), Haag-Streit (LenStar), Oculus (Pentacam AXL), Movu (Argos), Nidek (AL-Scan), Tomey (OA-2000), Topcon EU/VisiaImaging (Aladdin), Ziemer (Galilei G6) and all A-scan biometer manufacturers; but not Alcon (Verion). GS is a consultant for SIFI. The authors declare that they have no competing interests.

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