Calculation of Intraocular Lens Optical Power with Enhanced Depth of Focus

Relevance.  The new Increased Depth of Focus (EDOF) Intraocular Lens (IOL) technology is designed to improve the correction of visual acuity at a medium distance without compromising distance vision correction and provides a restoration of visual acuity in the distance and at an average distance, but at the same time a lower frequency of side optical phenomena and better contrast sensitivity compared to other multifocal IOLs (MIOL). Regardless of the technology used and the type of lens, the result of surgery and patient satisfaction depend on the optimization of the calculation of the optical strength of the IOL. To date, there is no consensus in the available literature on the choice of a formula for calculating the optical power of known EDOF IOLs.

Aim. Retrospective analysis of the accuracy of 7 formulas for optical power calculation of a new extended depth of focus intraocular lens.

Methods. The retrospective study included 34 patients (62 eyes) with implantation of a new EDOF Tecnis Symfony IOL ZXR00. The mean age of the patients was 61.9 ± 9.4 (39–87) years. IOL optical power range was +5.0 to +30.0 D, target refraction was –0.25 to 0.25 D. The average follow-up period for the patients was 12.3 ± 1.8 months. The SRK/T, Barrett Universal II, Haigis, Hoffer Q, Holladay 2, Olsen, and Kane formulas were retrospectively analyzed for effectiveness using appropriate constants. Each formula was optimized for the study group of patients to achieve an average refractive error as close to zero as possible. For each formula, the mean error (ME), mean absolute error (MAE), standard deviation (SD), median absolute error (MedAE), maximum absolute error (MaxAE), and percentage of eyes within the error range of 0.25, 0.5, 1.0, and 2.0 D were calculated.

Results. The optimized constants were LF = 2.21, a0 = 1.43, a1 = 0.39, a2 = 0.12, personalized ACD=5.68, ACD (Hoffer Q / Holladay 2) = 5.68/5.66, A-constant (SRK/T / Kane) = 119.5/119.4. For the SRK/T, Barrett Universal II, Kane and Haigis formulas the lowest MAE is shown. Application of the Hoffer Q and Holladay 2 formulas are associated with the highest MAE. The Barrett Universal II, SRK/T, Kane, and Haigis formulas were characterized by the highest percentage of reaching refraction of ±0.25 D (64, 62, 59, and 53, respectively). For all of the formulas examined, the frequency of reaching refraction of ±1.00 D was greater than 90% and within ±2.00 D greater than 97%.

Conclusion. This study was the first to retrospectively compare seven formulas for calculating the optical power of a new intraocular lens with an enhanced depth of focus. The SRK/T, Barrett Universal II, Haigis, and Kane formulas are recommended for calculating the optical power of the indicated IOL in clinical practice.

1. Pershin K.B., Pashinova N.F., Tsygankov A.Iu., Miyovich O.P., Likh I.A., Gurmizov E.P. Binocular implantation of new diffractive trifocal intraocular lens for presbyopia correction. Medical journal of the Russian Federation. 2018;24(5):228–232. (In Russ.) https://doi.org/10.18821/0869-2106-2018-24-5-228-232

2. Dick H.B., Piovella M., Vukich J., Vilupuru S., Lin L. Clinical Investigators. Prospective multicenter trial of a small-aperture intraocular lens in cataract surgery. J Cataract Refract Surg. 2017;43(7):956–968. https://doi.org/10.1016/j.jcrs.2017.04.038

3. Pershin K.B., Pashinova N.F., Tsygankov A.Iu., Legkikh S.L., Afaunova Z.Kh. Partial coherence laser interferometry and immersion ultrasonography for IOL power calculations in myopia. Cataract and refractive surgery. 2017;17(1):10–16. (In Russ.)

4. Cochener B. Clinical outcomes of a new extended range of vision intraocular lens: International Multicenter Concerto Study. J Cataract Refract Surg. 2016;42(9):1268–1275. https://doi.org/10.1016/j.jcrs.2016.06.033

5. Sachdev G., Ramamurthy S., Sharma U., Dandapani R. Visual outcomes of patients bilaterally implanted with the extended range of vision intraocular lens: A prospective study. Indian J Ophthalmol. 2018;66(3):407–410. https://doi.org/10.4103/ijo.IJO_813_17

6. Mendicute J., Kapp A., Lévy P., Krommes G., Arias-Puente A., Tomalla M., Barraquer E., Rozot P., Bouchut P. Evaluation of visual outcomes and patient satisfaction after implantation of a diffractive trifocal intraocular lens. J Cataract Refract Surg. 2016;42(2):203–210. https://doi.org/10.1016/j.jcrs.2015.11.037

7. De Silva S.R., Evans J.R., Kirthi V., Ziaei M., Leyland M. Multifocal versus monofocal intraocular lenses after cataract extraction. Cochrane Database Syst Rev. 2016;2016(12). https://doi.org/10.1002/14651858.CD003169.pub4

8. Pershin K.B., Pashinova N.F., Tsygankov A.Yu., Miyovitch O.P. The outcomes of the implantation of bifocal and trifocal IOLs for presbyopia. Cataract and refractive surgery. 2016;16(2):23–29. (In Russ.)

9. Pershin K.B., Pashinova N.F., Konovalova M.M., Tsygankov A.Yu., Konovalov M.E., Temirov N.E. Short term analysis of new single-piece aspheric diffractive trifocal intraocular lens implantation. Ophthalmology in Russia. 2019;16(1):19–25. (In Russ.) https://doi.org/10.18008/1816-5095-2019-1-19-25

10. Cochener B., Boutillier G., Lamard M., Auberger-Zagnoli C. A comparative evaluation of a new generation of diffractive trifocal and extended depth of focus intraocular lenses. J Refract Surg. 2018;34(8):507–514. https://doi.org/10.3928/1081597X-20180530-02

11. Torun Acar B., Duman E., Simsek S. Clinical outcomes of a new diffractive trifocal intraocular lens with Enhanced Depth of Focus (EDOF). BMC Ophthalmol. 2016;16(1):1–9. https://doi.org/10.1186/s12886-016-0389-8

12. Mencucci R., Favuzza E., Caporossi O., Savastano A., Rizzo S. Comparative analysis of visual outcomes, reading skills, contrast sensitivity, and patient satisfaction with two models of trifocal diffractive intraocular lenses and an extended range of vision intraocular lens. Graefe’s Arch Clin Exp Ophthalmol. 2018;256(10):1913–1922. https://doi.org/10.1007/s00417-018-4052-3

13. Kohnen T., Suryakumar R. Extended depth-of-focus technology in intraocular lenses. J Cataract Refract Surg. 2020;46(2):298–304. https://doi.org/10.1097/j.jcrs.0000000000000109

14. Kohnen T. The burden of too many intraocular lens choices. J Cataract Refract Surg. 2020;46(2):167. https://doi.org/10.1097/j.jcrs.0000000000000128

15. Pershin К.B., Pashinova N.F., Tsygankov А.Yu., Antonov E.A. First experience of multifocal and toric extended depth of focus intraocular lenses implantation (short-term analysis). Ophthalmology in Russia. 2021;18(3):408–414. (In Russ.) https://doi.org/10.18008/1816-5095-2021-3-408-414

16. Pershin K.B., Pashinova N.F., TsygankovA.Iu., Legkih S.L., Lih I.A. Biometry in lOL power calculations as a factor of successive cataract surgery. Cataract and refractive surgery. 2016;16(2):15–22. (In Russ.)

17. Bellucci R., Cargnoni M., Bellucci C. Clinical and aberrometric evaluation of a new extended depth-of-focus intraocular lens based on spherical aberration. J Cataract Refract Surg. 2019;45(7):919–926. https://doi.org/10.1016/j.jcrs.2019.02.023

18. Kohnen T., Böhm M., Hemkeppler E., Schönbrunn S., De Lorenzo N., Petermann K., Herzog M. Visual performance of an extended depth of focus intraocular lens for treatment selection. Eye. 2019;33(10):1556–1563. https://doi.org/10.1038/s41433-019-0443-x

19. Schallhorn S.C., Teenan D., Venter J.A., Hannan S.J., Schallhorn J.M. Initial clinical outcomes of a new extended depth of focus intraocular lens. J Refract Surg. 2019;35(7):426–433. https://doi.org/10.3928/1081597X-20190530-01

20. Ganesh S., Brar S., Pawar A., Relekar K.J. Visual and refractive outcomes following bilateral implantation of extended range of vision intraocular lens with micromonovision. J Ophthalmol. 2018;2018. https://doi.org/10.1155/2018/7321794

21. Monaco G., Gari M., Di Censo F., Poscia A., Ruggi G., Scialdone A. Visual performanceafter bilateral implantation of 2 new presbyopia-correcting intraocular lenses: Trifocalversus extended range of vision. J Cataract Refract Surg. 2017;43(6):737–747. https://doi.org/10.1016/j.jcrs.2017.03.037

22. Pedrotti E., Carones F., Aiello F., Mastropasqua R., Bruni E., Bonacci E., Talli P., Nucci C., Mariotti C., Marchini G. Comparative analysis of visual outcomes with 4 intraocular lenses: Monofocal, multifocal, and extended range of vision. J Cataract Refract Surg. 2018;44(2):156–167. https://doi.org/10.1016/j.jcrs.2017.11.011

23. Ruiz-Mesa R., Abengózar-Vela A., Aramburu A., Ruiz-Santos M. Comparison of visual outcomes after bilateral implantation of extended range of vision and trifocal intraocular lenses. Eur J Ophthalmol. 2017;27(4):460–465. https://doi.org/10.5301/ejo.5000935

24. Pandit R.T. Monocular clinical outcomes and range of near vision following cataract surgery with implantation of an extended depth of focus intraocular lens. J Ophthalmol. 2018;2018:8205824. https://doi.org/10.1155/2018/8205824