Visual acuity in patients with keratoconus: a comparison with matched regular myopic astigmatism

  • Michael MimouniEmail author
  • Riham Najjar
  • Gilad Rabina
  • Igor Vainer
  • Igor Kaiserman



To compare uncorrected distance visual acuity (UDVA) and best-corrected distance visual acuity (CDVA) between patients with keratoconus (KC) and matched patients with regular myopic astigmatism.


This retrospective study included consecutive patients diagnosed with KC between 2008 and 2013 at Care-Vision Laser Centers, Tel-Aviv, Israel, and matched patients with regular myopic astigmatism. Data included were central corneal thickness (CCT), spherical equivalent (SE), cylinder (CYL), mean keratometric power, maximum keratometric power (Kmax), UDVA, CDVA, and defocus equivalent (DEQ).


The KC group included 734 patients with a mean age of 33.8 ± 9.5 years. The matched, control group included 1462 patients with a mean age of 33.2 ± 9.7 years (p = 0.14). The mean SE and CYL of the KC group were − 3.34 ± 3.29D and − 3.01 ± 1.99D, respectively, compared to − 3.34 ± 2.92D (p = 0.98) and − 2.97 ± 1.35 (p = 0.58). Mean K (46.8 ± 3.3D versus 44.0 ± 1.8D, p < 0.0001) and Kmax (48.4 ± 4.0D versus 45.3 ± 2.0D, p < 0.0001) were statically significant higher in the KC group. CCT was significantly thinner in the KC group (444 ± 49 versus 527 ± 40 μm, p < 0.0001). The KC group had a better UDVA than the non-KC group (1.10 ± 0.68 versus 1.22 ± 0.64 logMAR, p < 0.0001). CDVA was significantly lower in the KC group (p < 0.001).


For defocus equivalents above 6D, the KC group had better UDVA than the non-KC group in spite of worse CDVA.


Keratoconus Astigmatism UDVA CDVA Defocus equivalent 


Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

This study followed the tenets of the Declaration of Helsinki. The research was approved by the Institutional Review Board of the Barzilai Medical Center.

Informed consent

Due to the retrospective nature of this study, there was no need for a signed informed consent from patients.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of Ophthalmology, Rambam Health Care Campus and Ruth Rappaport Faculty of MedicineTechnion-Israel Institute of TechnologyHaifaIsrael
  2. 2.Department of Ophthalmology, Barzilai Medical Center, Ashkelon and the Faculty of Health SciencesBen-Gurion University of the NegevBeer ShebaIsrael
  3. 3.Division of OphthalmologySourasky Medical Center, Sackler School of MedicineTel AvivIsrael
  4. 4.Care-Vision Laser CentersTel-AvivIsrael

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