Comparison of refractive outcomes using conventional keratometry or total keratometry for IOL power calculation in cataract surgery

  • Sabong Srivannaboon
  • Chareenun ChirapapaisanEmail author



To compare the refractive outcomes following cataract surgery using conventional keratometry (K) and total keratometry (TK) for intraocular lens (IOL) calculation in the SRK/T, HofferQ, Haigis, and Holladay 1 and 2, as well as Barrett and Barrett TK Universal II formulas.


Sixty eyes of 60 patients from Siriraj Hospital, Thailand, were prospectively enrolled in this comparative study. Eyes were assessed using a swept-source optical biometer (IOLMaster 700; Carl Zeiss Meditec, Jena, Germany). Posterior keratometry, K, TK, central corneal thickness, anterior chamber depth, lens thickness, axial length, and white-to-white corneal diameter were recorded. Emmetropic IOL power was calculated using K and TK in all formulas. Selected IOL power and predicted refractive outcomes were recorded. Postoperative manifest refraction was measured 3 months postoperatively. Mean absolute errors (MAEs), median absolute errors (MedAEs), and percentage of eyes within ± 0.25, ± 0.50, and ± 1.00 D of predicted refraction were calculated for all formulas in both groups.


Mean difference between K and TK was 0.03 D (44.56 ± 1.18 vs. 44.59 ± 1.22 D), showing excellent agreement (ICC = 0.99, all p < 0.001). Emmetropic IOL powers in all formulas for both groups were very similar, with a trend toward lower MAEs and MedAEs for TK when compared with K. The Barrett TK Universal II formula demonstrated the lowest MAEs. Proportion of eyes within ± 0.25, ± 0.50, and ± 1.00 D of predicted refraction were slightly higher in the TK group.


Conventional K and TK for IOL calculation showed strong agreement with a trend toward better refractive outcomes using TK. The same IOL constant can be used for both K and TK.


Keratometry Total keratometry Intraocular lens Power calculation Cataract surgery Refractive outcomes 


Compliance with ethical standards

Conflict of interest

The first author has received a speaker honorarium from Company Carl Zeiss; the second author declares that she has no conflict of interest.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the Faculty of Medicine Siriraj Hospital, Mahidol University and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.


  1. 1.
    Sano M, Hiraoka T, Ueno Y (2016) Influence of posterior corneal astigmatism on postoperative refractive astigmatism in pseudophakic eyes after cataract surgery. BMC Ophthalmol 16:212CrossRefGoogle Scholar
  2. 2.
    Reitblat O, Levy A, Kleinmann G, Abulafia A, Assia EI (2016) Effect of posterior corneal astigmatism on power calculation and alignment of toric intraocular lenses: comparison of methodologies. J Cataract Refract Surg 42:217–225CrossRefGoogle Scholar
  3. 3.
    Savini G, Næser K (2015) An analysis of the factors influencing the residual refractive astigmatism after cataract surgery with toric intraocular lenses. Invest Ophthalmol Vis Sci 13:827–835CrossRefGoogle Scholar
  4. 4.
    Savini G, Hoffer KJ, Lomoriello DS, Ducoli P (2017) Simulated keratometry versus total corneal power by ray tracing: a comparison in prediction accuracy of intraocular lens power. Cornea 36:1368–1372CrossRefGoogle Scholar
  5. 5.
    Kirgiz A, Atalay K, Kaldirim H, Cabuk KS, Akdemir MO, Taskapili M (2017) Scheimpflug camera combined with placido-disk corneal topography and optical biometry for intraocular lens power calculation. Int Ophthalmol 37:781–786CrossRefGoogle Scholar
  6. 6.
    Saad E, Shammas MC, Shammas HJ (2013) Scheimpflug corneal power measurements for intraocular lens power calculation in cataract surgery. Am J Ophthalmol 156:460–467CrossRefGoogle Scholar
  7. 7.
    Srivannaboon S, Chotikavanich S, Chirapapaisan C, Kasemson S, Po-ngam W (2012) Precision analysis of posterior corneal topography measured by Visante Omni: repeatability, reproducibility, and agreement with Orbscan II. J Refract Surg 28:133–138CrossRefGoogle Scholar
  8. 8.
    Aramberri J, Araiz L, Garcia A, Illarramendi I, Olmos J, Oyanarte I, Romay A, Vigara I (2012) Dual versus single Scheimpflug camera for anterior segment analysis: precision and agreement. J Cataract Refract Surg 38:1934–1949CrossRefGoogle Scholar
  9. 9.
    Chan TCY, Biswas S, Yu M, Jhanji V (2017) Comparison of corneal measurements in keratoconus using swept-source optical coherence tomography and combined Placido-Scheimpflug imaging. Acta Ophthalmol 95:486–e494. CrossRefGoogle Scholar
  10. 10.
    Rosner B (2000) Fundamental of biostatistic. Duxbury, CaliforniaGoogle Scholar
  11. 11.
    Shajari M, Kolb CM, Petermann K, Böhm M, Herzog M, de’Lorenzo N, Schönbrunn S, Kohnen T (2018) Comparison of 9 modern intraocular lens power calculation formulas for a quadrifocal intraocular lens. J Cataract Refract Surg 44:942–948CrossRefGoogle Scholar
  12. 12.
    Fabian E, Wehner W (2019) Prediction accuracy of total keratometry compared to standard keratometry using different intraocular lens power formulas. J Refract Surg 35:362–368CrossRefGoogle Scholar
  13. 13.
    Wang L, Koch DD, Hill W, Abulafia A (2017) Pursuing perfection in intraocular lens calculations: III. Criteria for analyzing outcomes. J Cataract Refract Surg 43:999–1002CrossRefGoogle Scholar
  14. 14.
    Aristodemou P, Cartwright NK, Sparrow JM, Johnston R (2011) Intraocular lens calculations. Ophthalmology 118:1221CrossRefGoogle Scholar
  15. 15.
    Lachin JM (1992) Power and sample size evaluation for the McNemar test with application to matched case-control studies. Stat Med 11:1239–1251CrossRefGoogle Scholar
  16. 16.
    Tang M, Wang L, Koch DD, Li Y, Huang D (2012) Intraocular lens power calculation after previous myopic laser vision correction based on corneal power measured by Fourier-domain optical coherence tomography. J Cataract Refract Surg 238:589–594CrossRefGoogle Scholar
  17. 17.
    Qazi MA, Cua IY, Roberts CJ, Pepose JS (2007) Determining corneal power using Orbscan II videokeratography for intraocular lens calculation after excimer laser surgery for myopia. J Cataract Refract Surg 33:21–30CrossRefGoogle Scholar
  18. 18.
    Kwitko S, Marinho DR, Rymer S, Severo N, Arce CG (2012) Orbscan II and double-K method for IOL calculation after refractive surgery. Graefes Arch Clin Exp Ophthalmol 2250:1029–1034CrossRefGoogle Scholar
  19. 19.
    Shammas HJ, Hoffer KJ, Shammas MC (2009) Scheimpflug photography keratometry readings for routine intraocular lens power calculation. J Cataract Refract Surg 35:330–334CrossRefGoogle Scholar
  20. 20.
    Ayala M, Strandås R (2015) Accuracy of optical coherence tomography (OCT) in pachymetry for glaucoma patients. BMC Ophthalmol 15:124Google Scholar
  21. 21.
    Gullstrand A (1911) Einfihrung in die Methoden der Dioptrik des Auges des Menschen. Hirzel, LeipzigGoogle Scholar
  22. 22.
    Stenstrom S (1964) Optics and the eye. Goteborg, AkademiforlagetGoogle Scholar
  23. 23.
    Olsen T (1986) On the calculation of power from curvature of the cornea. Br J Ophthalmol 70:152–154CrossRefGoogle Scholar
  24. 24.
    Hoffer KJ, Aramberri J, Haigis W, Olsen T, Savini G, Shammas HJ, Bentow S (2015) Protocols for studies of intraocular lens formula accuracy. Am J Ophthalmol 160:403–405CrossRefGoogle Scholar
  25. 25.
    Aristodemou P, Knox Cartwright NE, Sparrow JM, Johnston RL (2011) Intraocular lens formula constant optimization and partial coherence interferometry biometry: refractive outcomes in 8108 eyes after cataract surgery. J Cataract Refract Surg 37:50–62CrossRefGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Department of Ophthalmology, Faculty of Medicine Siriraj HospitalMahidol UniversityBangkokThailand

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