Refractive Outcomes of Non-Toric and Toric Intraocular Lenses in Mild, Moderate and Advanced Keratoconus: A Systematic Review and Meta-Analysis

Tal Yahalomi, Asaf Achiron, Idan Hecht, Roee Arnon, Eliya Levinger, Joseph Pikkel, Raimo Tuuminen

Research output: Contribution to journalReview articlepeer-review

9 Scopus citations


Background: To perform a systematic review and meta-analysis of the refractive outcomes of non-toric and toric intraocular lenses (IOLs) in keratoconus (KC) using different IOL power calculation formulas. Methods: A systematic search was conducted to identify studies that report on refractive outcomes of different IOL power calculation formulas in KC patients undergoing cataract surgery. Inclusion criteria were primary posterior chamber non-toric and toric monofocal intraocular lens implantation, data on the degree of KC, explicit mention of the formula used for each stage of KC, and the number of eyes in each category. We calculated and compared the absolute and mean prediction errors, percentage of eyes within 0.5 D and 1 D from target, and the weighted absolute prediction errors of IOL formulas, all were given for KC degrees I–III. Results: The bibliographic search yielded 582 studies published between 1996 and 2020, 14 of which (in total 456 eyes) met the criteria: three studies on non-toric IOL (98 eyes), eight studies on toric IOLs (98 eyes) and three studies of unknown separation between non-toric and toric IOLs (260 eyes). The lowest absolute prediction error (APE) for mild, moderate, and advanced KC was seen with Kane’s IOL power formula with keratoconus adjustment. The APE for the top five IOL power formulas ranged 0.49–0.73 diopters (D) for mild (83–94%) of eyes within 1 D from the target), 1.08–1.21 D for moderate (51–57% within 1 D), and 1.44–2.86 D for advanced KC (12–48% within 1 D). Conclusions: Cataract surgery in eyes with mild-to-moderate KC generally achieves satisfactory postoperative refractive results. In patients with advanced KC, a minority of the eyes achieved spherical equivalent refraction within 1 D from the target. The Kane’s formula with keratoconus adjustment showed the best results in all KC stages.

Original languageEnglish
Article number2456
JournalJournal of Clinical Medicine
Issue number9
StatePublished - 27 Apr 2022
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2022 by the authors. Licensee MDPI, Basel, Switzerland.


The study was supported by grants from the Finnish Eye Foundation, Finnish Medical Foundation, Finnish Ophthalmological Society, the Friends for the Blind, the Nissi Foundation, the Paulo Foundation, the Waldemar von Frenckell Foundation, and the HUS Specific Catchment Area (ERVA) Clinical Research Grants (ERV499, ERV521, EVO116, EVO117, EVO315). Tuuminen is a scientific adviser (advisory board, honoraria) to Alcon Laboratories, Inc., Allergan, Inc., Bayer AG, and Novartis AG, and has received clinical trial support (study medicines) from Bayer AG and Laboratoires Th?a. The authors have neither proprietary nor commercial interests in any medications or materials discussed.

FundersFunder number
Alcon Laboratories, Inc., Allergan, Inc.
Finnish Ophthalmological Society
Friends for the Blind
Laboratoires Th?a
Nissi Foundation
Suomen Lääketieteen Säätiö
Paulon Säätiö
Waldemar von Frenckells StiftelseERV499, ERV521, EVO116, EVO117, EVO315


    • biometry
    • intraocular lens power calculation formula
    • keratoconus
    • refractive error
    • spherical equivalent


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