Journal of Ophthalmic and Vision Research

Published date: Nov 10 2025

Journal Title: Journal of Ophthalmic and Vision Research

Issue title: ‎Volume 20 - 2025

Pages: 1 - 8

DOI: 10.18502/jovr.v20.17679

Firouze Hatamifirouze.hatami1376@gmail.comOphthalmic Research Center, Research Institute for Ophthalmology and Vision Science, Shahid Beheshti University of Medical Sciences, Tehran

Sina Khosravi Mirzaeisinakhosravi1997@gmail.comOphthalmic Research Center, Research Institute for Ophthalmology and Vision Science, Shahid Beheshti University of Medical Sciences, Tehran

Mohammad Ali Javadima_javadi@yahoo.comOphthalmic Research Center, Research Institute for Ophthalmology and Vision Science, Shahid Beheshti University of Medical Sciences, Tehran

Sepehr Feizisepehrfeizi@yahoo.comOcular Tissue Engineering Research Center, Research Institute for Ophthalmology and Vision Science, Shahid Beheshti University of Medical Sciences, Tehran

Sare Safisaresafi.s@gmail.comOphthalmic Epidemiology Research Center, Research Institute for Ophthalmology and Vision Science, Shahid Beheshti University of Medical Sciences, Tehran

Seyed Bagher Hosseinihoseiniba@gmail.comOphthalmic Research Center, Research Institute for Ophthalmology and Vision Science, Shahid Beheshti University of Medical Sciences, Tehran

Purpose: To compare the refractive accuracy of different intraocular lens (IOL) power calculation formulas in eyes with keratoconus (KCN) undergoing cataract surgery.

Methods: This retrospective case series included the medical records of patients with KCN who underwent optical biometry and cataract surgery with IOL implantation. The predicted spherical equivalent (SE) values were calculated using the Holladay 1, Hoffer Q, SRK/T, and SRK II formulas. Additionally, a subgroup analysis was performed for eyes with available data on anterior chamber depth to compare the accuracy of Haigis, Barrett Universal II, Barrett True-K, EVO 2.0, Kane, and Kane KCN formulas. The mean prediction error (PE), mean absolute error (MAE), median absolute error, and the percentage of eyes within a PE of ±0.25 diopters (D), ±0.50 D, ±0.75 D, and ±1.00 D were calculated.

Results: Forty-seven eyes of 30 patients were included. The MAE was significantly different among the Holladay 1, Hoffer Q, SRK/T, and SRK II formulas. The Holladay 1 and Hoffer Q formulas led to a hyperopic refractive shift. The SRK/T and SRK II formulas tended toward a myopic refractive outcome. The MAE was lowest for the SRK/T formula (0.39 D), followed by the Holladay 1 (0.48 D), Hoffer Q (0.59 D), and SRK II (0.87 D). Statistical analysis revealed a significantly lower MAE for the SRK/T formula compared to the Hoffer Q and SRK II formulas (P < 0.05). The percentage of eyes within a PE of ±0.50 D was 70.2% for SRK/T, 57.44% for Holladay 1, 48.93% for Hoffer Q, and 29.78% for SRK II. The subgroup analysis comprising 11 eyes showed no significant difference among six other formulas (Haigis, Barrett Universal II, Barrett True K, EVO 2.0, Kane, and Kane KCN), with Barrett True-K having the least MAE.

Conclusion: The SRK/T was the most accurate IOL power calculation formula in this study, and Holladay 1 could be an alternative choice. SRK II had the lowest accuracy in predicting refractive outcomes. Among modern formulas, Barrett True-K demonstrated the highest accuracy in eyes with KCN.

Keywords: Cataract Surgery, Intraocular Lens Power Calculation Formula, Keratoconus

1. Krachmer JH, Feder RS, Belin MW. Keratoconus and related noninflammatory corneal thinning disorders. Surv Ophthalmol 1984;28:293–322.

2. Asimellis G, Kaufman EJ. Keratoconus. StatPearls Publishing; 2017.

3. Thebpatiphat N, Hammersmith KM, Rapuano CJ, Ayres BD, Cohen EJ. Cataract surgery in keratoconus. Eye Contact Lens 2007;33:244–246.

4. Aiello F, Nasser QJ, Nucci C, Angunawela RI, Gatzioufas Z, Maurino V. Cataract surgery in patients with keratoconus: Pearls and pitfalls. Open Ophthalmol J 2017;11:194–200.

5. Thebpatiphat N, Hammersmith KM, Rapuano CJ, Ayres BD, Cohen EJ. Cataract surgery in keratoconus. Eye Contact Lens 2007;33:244–246.

6. Melles RB, Holladay JT, Chang WJ. Accuracy of intraocular lens calculation formulas. Ophthalmology 2018;125:169– 178.

7. Yahalomi T, Achiron A, Hecht I, Arnon R, Levinger E, Pikkel J, et al. Refractive outcomes of non-toric and toric intraocular lenses in mild, moderate and advanced keratoconus: A systematic review and meta-analysis. J Clin Med 2022;11:2456.

8. Camps VJ, Piñero DP, Caravaca-Arens E, de Fez D, Pérez- Cambrodí RJ, Artola A. New approach for correction of error associated with keratometric estimation of corneal power in keratoconus. Cornea 2014;33:960–967.

9. Kamiya K, Shimizu K, Igarashi A, Miyake T. Assessment of anterior, posterior, and total central corneal astigmatism in eyes with keratoconus. Am J Ophthalmol 2015;160:851– 857.e1.

10. Kim J, Whang WJ, Kim HS. Analysis of total corneal astigmatism with a rotating Scheimpflug camera in keratoconus. BMC Ophthalmol 2020;20:475.

11. Kane JX, Connell B, Yip H, McAlister JC, Beckingsale P, Snibson GR, et al. Accuracy of intraocular lens power formulas modified for patients with keratoconus. Ophthalmology 2020;127:1037–1042.

12. Watson MP, Anand S, Bhogal M, Gore D, Moriyama A, Pullum K, et al. Cataract surgery outcome in eyes with keratoconus. Br J Ophthalmol 2014;98:361–364.

13. Saglik A, Celik H. Comparison of Holladay equivalent keratometry readings and anterior corneal surface keratometry measurements in keratoconus. Int Ophthalmol 2019;39:1501–1509.

14. Hashemi H, Heidarian S, Seyedian MA, Yekta A, Khabazkhoob M. Evaluation of the results of using toric IOL in the cataract surgery of keratoconus patients. Eye Contact Lens 2015;41:354–358.

15. Savini G, Abbate R, Hoffer KJ, Mularoni A, Imburgia A, Avoni L, et al. Intraocular lens power calculation in eyes with keratoconus. J Cataract Refract Surg 2019;45:576– 581.

16. Wang KM, Jun AS, Ladas JG, Siddiqui AA, Woreta F, Srikumaran D. Accuracy of intraocular lens formulas in eyes with keratoconus. Am J Ophthalmol 2020;212:26– 33.

17. Heath MT, Mulpuri L, Kimiagarov E, Patel RP, Murphy DA, Levine H, et al. Intraocular lens power calculations in keratoconus eyes comparing keratometry, total keratometry, and newer formulae. Am J Ophthalmol 2023;253:206–214.

18. Ghiasian L, Abolfathzadeh N, Manafi N, Hadavandkhani A. Intraocular lens power calculation in keratoconus: A review of literature. J Curr Ophthalmol 2019;31:127–134.

19. Krumeich JH, Daniel J, Knülle A. Live-epikeratophakia for keratoconus. J Cataract Refract Surg 1998;24:456–463.

20. Holladay JT, Prager TC, Chandler TY, Musgrove KH, Lewis JW, Ruiz RS. A three-part system for refining intraocular lens power calculations. J Cataract Refract Surg 1988;14:17–24.

21. Hoffer KJ. The Hoffer Q formula: A comparison of theoretic and regression formulas. J Cataract Refract Surg 1993;19:700–712.

22. Retzlaff JA, Sanders DR, Kraff MC. Development of the SRK/T intraocular lens implant power calculation formula. J Cataract Refract Surg 1990;16:333–340.

23. Retzlaff J. A new intraocular lens calculation formula. J Am Intraocul Implant Soc 1980;6:148–152.

24. Sanders DR, Kraff MC. Improvement of intraocular lens power calculation using empirical data. J Am Intraocul Implant Soc 1980;6:263–267.

25. Haigis W, Lege B, Miller N, Schneider B. Comparison of immersion ultrasound biometry and partial coherence interferometry for intraocular lens calculation according to Haigis. Graefes Arch Clin Exp Ophthalmol 2000;238:765– 773.

26. Barrett G. Barrett Universal II Formula. http://calc.apacrs.org/barrett_universal2105/

27. Barrett True K. Formula - For prior myopic or hyperopic lasik/prk/rk + kc. https://calc.apacrs.org/ Barrett_True_K_Universal_2105/

28. Yeo TK. EVO formula. https://www.evoiolcalculator.com/

29. Kane JX. Kane formula. www.iolformula.com https://doi.org/10.1007/978-3-031-50666-6_46.

30. ULIB. Optimized IOL constants for the ZEISS IOLMaster 2016. http://ocusoft.de/ulib/c1.htm

31. Cooke DL, Cooke TL. Comparison of 9 intraocular lens power calculation formulas. J Cataract Refract Surg 2016;42:1157–1164.

32. Tomidokoro A, Oshika T, Amano S, Higaki S, Maeda N, Miyata K. Changes in anterior and posterior corneal curvatures in keratoconus. Ophthalmology 2000;107:1328–1332.

33. Camps VJ, Piñero DP, Caravaca E, De Fez D. Preliminary validation of an optimized algorithm for intraocular lens power calculation in keratoconus. Indian J Ophthalmol 2017;65:690–699.

34. Piñero DP, Camps VJ, Caravaca-Arens E, Pérez-Cambrodí RJ, Artola A. Estimation of the central corneal power in keratoconus: Theoretical and clinical assessment of the error of the keratometric approach. Cornea 2014;33:274– 279.

35. Kamiya K, Iijima K, Nobuyuki S, Mori Y, Miyata K, Yamaguchi T, et al. Predictability of intraocular lens power calculation for cataract with keratoconus: A multicenter study. Sci Rep 2018;8:1312.

36. Garzón N, Arriola-Villalobos P, Felipe G, Poyales F, García- Montero M. Intraocular lens power calculation in eyes with keratoconus. J Cataract Refract Surg 2020;46:778–783.

37. Haigis W. Occurrence of erroneous anterior chamber depth in the SRK/T formula. J Cataract Refract Surg 1993;19:442–446.

38. Sheard RM, Smith GT, Cooke DL. Improving the prediction accuracy of the SRK/T formula: The T2 formula. J Cataract Refract Surg 2010;36:1829–1834.

39. Hoffer KJ, Aramberri J, Haigis W, Olsen T, Savini G, Shammas HJ, et al. Protocols for studies of intraocular lens formula accuracy. Am J Ophthalmol 2015;160:403–405.e1.