Site Overlay

Sources of refractive errors in calculating the optical power of intraocular lenses in the treatment of cataract patients

Volume 11, Issue 1

Original Article / Published: November 2023


Т. Kirova, A. Kalaydzhiev, L. Voynov, G. Yordanov

Department of “Ophthalmology, Otorhinolaryngology and Oral Surgery”, Clinic of Ophthalmology, Military Medical Academy, Sofia


Purpose: Cataract surgery is the most common surgical procedure worldwide, the goal of which is not only to restore the patient’s vision, but to obtain a perfect refractive result that meets the expectations of complete independence from glasses. Unexpected poor refractive outcome after cataract surgery (refractive error) is an unsolved problem, despite increasingly better postoperative outcomes. Improving the postoperative refractive outcome requires an analysis of the sources of refractive errors. This is also the purpose of the present study.

Methods: The subject and object of the study were cataract patients with indications for surgical treatment by phacoemulsification (FE) and implantation of an artificial intraocular lens (IOL). The results of the operations of 235 eyes in 160 patients (80 women and 80 men) who underwent surgery in the eye clinic of the Academy of Medical Sciences-Sofia for the period 2018-2020 were analyzed.

Results: Of all the measured keratometric parameters, only the value of the cylinder before phacoemulsification is a risk factor, as when it rises above ±1.0D, the risk doubles, and when the value exceeds 2.0D, it becomes 2.4 times greater. The ratio of POC to AL is a statistically significant risk factor for the occurrence of refractive error, with a ratio of POC/AL <0.30, the risk is 2.3 times greater. Conclusion: In the present study, in 62.6% of cases or 2/3 of the eyes, the set Target was successfully met with a minimum permissible refractive error of AE<±0.50D. This determines the effectiveness of the surgical procedure as high.


  1. Попова Г.Д. Източници на рефрактивни грешки при изчисляване на оптичната сила на интраокуларните лещи при лечение на пациенти с катаракта; дисертационен
    труд- 2018г-София;1-2;5- 6;10-28
  2. Olsen T, Nielsen PJ. Immersion versus contact technique in the measurement of axial length by ultrasound. Acta Ophthalmol 1989; 67:101-102
  3. Olsen T. Improved accuracy of intraocular lens power calculation with the Zeiss IOLMaster, Acta Ophthalmologica Scandinavica.2007; V ol.85:84-87.
  4. Olsen T., Hoffmann P. C constant: new concept for ray tracing assisted intraocular lens power calculation. J Cataract RefractSurg, 2014; 40: 764-773
  5. Norrby S. Sources of error in intraocular lense power calculation. J.Cataract Refract Surg. 2008- Vol.34; 368-376
  6. European Registry of Quality Outcomes for Cataract and Refract Surgery
  7. Bending A, Montan P, Stenevi U, Kugelberg M, Zetterstrom C,
  8. Lundstrom M, Aiming for emetropia after cataract surgery: Swedish National Cataract Registry study. J Cataract Refract Surg. 2012 Jul;38(7):1181-6
  9. Norrby S. Sourses of errors in intraocular lens power calculation. J. Cataract. Refract. Surg.-2008 – Vol.34 – P.368-376
  10. John P. Fang, Warren Hill, Li Wang, Victor Chang, Douglas D Koch, Advanced Intraocular Lens Power Calculations
  11. John P. Fang, Warren Hill, Li Wang, Victor Chang, Douglas D Koch, Advanced Intraocular Lens Power Calculations
  12. Тахчиди Х.П., Панталеев Е.Н., Бессарабов А.Н., Формула расчета оптической сили IOL на основе параметризованного схематичного стандартного артефакичного глаза.
  13. Hagis W, Lege B, Miller N, Schneider B. Comparisson of immersion ultrasound biometry and partial coherence interfer- ometry for intraocular lens calculation according to Haigis.
    Graefe’s Arch Clin Exp Ophthalmol. 2000; 238(9):765-773
  14. Rajan MS, Keilhorn I, Bell JA. Partial coherence laser interferometry vs conventional ultrasound biometry in intraocular lens power calculation. Eye (Lond). 2002;16(5):552-556
  15. Cvetkovic A, Sreckovic S, Petrovic M. Comparison of biometric values and intraocular lens power calculations obtained by ultrasound and optical biometry, SER J EXP CLIN RES
  16. Hashemi H, et al. White-to-white corneal diameter distribution in an adult population. J Curr. Ophthalmology, 2015, 27:21-24
  17. Kalogeropolus C, Aspiotis M, Stefaniotou M et al. Factors influencing the accuracy of the SRK formula in the intraocular lens power calculation. Doc. Ophthalmol., 1994, v.85(3), p.223-242


intraocular lenses, cataract patients

How to cite this article:

Т. Kirova, A. Kalaydzhiev, L. Voynov, G. Yordanov. Sources of refractive errors in calculating the optical power of intraocular lenses in the treatment of cataract patients. Journal of Endourology and Minimally Invasive Surgery (Bulgaria), 2023; 11(1): 50-55

Corresponding author

Dr. Tanislava Kirova
Clinic of ophthalmology, Military Medical Academy, Blvd“ Georgi Sofiiski” 6, Sofia-1000, Bulgaria