Korean J Ophthalmol.  2017 Dec;31(6):479-488. 10.3341/kjo.2016.0078.

Intraocular Lens Power Calculation after Refractive Surgery: A Comparative Analysis of Accuracy and Predictability

• Kang BS
• Han JM
• Oh JY
• Kim MK
• Wee WR

• KMID: 2396698
• DOI: http://doi.org/10.3341/kjo.2016.0078

Abstract

PURPOSE
To compare the accuracy of intraocular lens (IOL) power calculation using conventional regression formulae or the American Society of Cataract and Refractive Surgery (ASCRS) IOL power calculator for previous corneal refractive surgery.
METHODS
We retrospectively reviewed 96 eyes from 68 patients that had undergone cataract surgery after keratorefractive surgeries. We calculated the formula with two approaches: IOL powers using the ASCRS IOL power calculator and IOL powers using conventional formulae with previous refractive data (Camellin, Jarade, Savini, and clinical history method) or without prior data (0, 2 and, 4 mm total mean power in topography, Wang-Koch-Maloney, Shammas, Seitz, and Maloney). Two conventional IOL formulae (the SRK/T and the Hoffer Q) were calculated with the single K and double K methods. Mean arithmetic refractive error and mean absolute error were calculated at the first postoperative month.
RESULTS
In conventional formulae, the Jarade method or the Seitz method, applied in the Hoffer Q formula with the single K or double K method, have the lowest prediction errors. The least prediction error was found in the Shammas-PL method in the ASCRS group. There was no statistically significant difference between the 10 lowest mean absolute error conventional methods, the Shammas-PL method and the Barrett True-K method calculated with using the ASCRS calculator, without using preoperative data.
CONCLUSIONS
The Shammas-PL formula and the Barrett True-K formula, calculated with the ASCRS calculator, without using history, were methods comparable to the 10 most accurate conventional formulae. Other methods using the ASCRS calculator show a myopic tendency.

Keyword

Cataract; Intraocular lens; Refractive surgical procedures

MeSH Terms

Cataract
Humans
Lenses, Intraocular*
Methods
Refractive Errors
Refractive Surgical Procedures*
Retrospective Studies

Figure

• 

  Fig. 1 A schematic study design illustration. ASCRS = American Society of Cataract and Refractive Surgery; IOL = intraocular lens; MARE = mean arithmetic refractive error; MAE = mean absolute error; Barrett True-K no Hx = Barrett True-K method without using preoperative data.

• 

  Fig. 2 Box plot of mean absolute error (MAE) of intraocular lens power prediction with various conventional methods. (A) Using preoperative data, (B) total mean power of topography, (C) no keratorefractive history before refractive surgery. Round mark (○) means outlier values which are between one and a half and three box lengths; asterisk (*) means extreme values which are more than three box lengths. DoubleK = the SRK/T formula with the double-K method; HoQDoubleK = the Hoffer Q formula with the double-K method; HoQSingleK = the Hoffer Q formula with the single-K method, SingleK = the SRK/T formula with the single-K method; Topo mean 0, 2, 4 mm = the total mean power at 0, 2, 4 mm in the topography method; W-K-M = the Wang-Koch-Maloney method.

• 

  Fig. 3 Box plot of mean arithmetic refractive error (MARE) of intraocular lens power prediction with various conventional methods. (A) Using preoperative data, (B) total mean power of topography, (C) no keratorefractive history before refractive surgery. Round mark (○) means outlier values which are between one and a half and three box lengths from either end of the box; asterisk (*) means extreme values which are more than three box lengths from either end of the box. DoubleK = the SRK/T formula with the double-K method; HoQDoubleK = the Hoffer Q formula with the double-K method; HoQSingleK = the Hoffer Q formula with the single-K method; SingleK = the SRK/T formula with the single-K method; Topo mean 0, 2, 4 mm = the total mean power at 0, 2, 4 mm in the topography method; W-K-M = the Wang-Koch-Maloney method.

• 

  Fig. 4 Box plot of mean absolute error (MAE) of intraocular lens power prediction with the American Society of Cataract and Refractive Surgery calculator. Round mark (○) means outlier values which are between one and a half and three box lengths; asterisk (*) means extreme values which are more than three box lengths. B-T-K noHx = Barrett True-K method without using preoperative data; W-K-M 0, 2 mm = Wang-Koch-Maloney method using topographic K at 0, 2 mm.

• 

  Fig. 5 Box plot of mean arithmetic refractive error (MARE) of intraocular lens power prediction with the American Society of Cataract and Refractive Surgery calculator. Round mark (○) means outlier values which are between one and a half and three box lengths from either end of the box; asterisk (*) means extreme values which are more than three box lengths from either end of the box. B-T-K noHx = Barrett True-K method without using preoperative data; W-K-M 0, 2 mm = Wang-Koch-Maloney method using topographic K at 0, 2 mm.

Reference

1. Hamilton DR, Hardten DR. Cataract surgery in patients with prior refractive surgery. Curr Opin Ophthalmol. 2003; 14:44–53.

2. Speicher L. Intra-ocular lens calculation status after corneal refractive surgery. Curr Opin Ophthalmol. 2001; 12:17–29.

3. Koch DD, Liu JF, Hyde LL, et al. Refractive complications of cataract surgery after radial keratotomy. Am J Ophthalmol. 1989; 108:676–682.

4. Odenthal MT, Eggink CA, Melles G, et al. Clinical and theoretical results of intraocular lens power calculation for cataract surgery after photorefractive keratectomy for myopia. Arch Ophthalmol. 2002; 120:431–438.

5. Seitz B, Langenbucher A, Nguyen NX, et al. Underestimation of intraocular lens power for cataract surgery after myopic photorefractive keratectomy. Ophthalmology. 1999; 106:693–702.

6. Borasio E, Stevens J, Smith GT. Estimation of true corneal power after keratorefractive surgery in eyes requiring cataract surgery: BESSt formula. J Cataract Refract Surg. 2006; 32:2004–2014.

7. Hoffer KJ. Intraocular lens power calculation for eyes after refractive keratotomy. J Refract Surg. 1995; 11:490–493.

8. Aramberri J. Intraocular lens power calculation after corneal refractive surgery: double-K method. J Cataract Refract Surg. 2003; 29:2063–2068.

9. Camellin M, Calossi A. A new formula for intraocular lens power calculation after refractive corneal surgery. J Refract Surg. 2006; 22:187–199.

10. Savini G, Barboni P, Zanini M. Intraocular lens power calculation after myopic refractive surgery: theoretical comparison of different methods. Ophthalmology. 2006; 113:1271–1282.

11. Jarade EF, Tabbara KF. New formula for calculating intraocular lens power after laser in situ keratomileusis. J Cataract Refract Surg. 2004; 30:1711–1715.

12. Seitz B, Langenbucher A. Intraocular lens calculations status after corneal refractive surgery. Curr Opin Ophthalmol. 2000; 11:35–46.

13. Savini G, Hoffer KJ, Carbonelli M, Barboni P. Intraocular lens power calculation after myopic excimer laser surgery: clinical comparison of published methods. J Cataract Refract Surg. 2010; 36:1455–1465.

14. Shammas HJ, Shammas MC, Garabet A, et al. Correcting the corneal power measurements for intraocular lens power calculations after myopic laser in situ keratomileusis. Am J Ophthalmol. 2003; 136:426–432.

15. Wang L, Booth MA, Koch DD. Comparison of intraocular lens power calculation methods in eyes that have undergone LASIK. Ophthalmology. 2004; 111:1825–1831.

16. Smith RJ, Chan WK, Maloney RK. The prediction of surgically induced refractive change from corneal topography. Am J Ophthalmol. 1998; 125:44–53.

17. Barrett GD. An improved universal theoretical formula for intraocular lens power prediction. J Cataract Refract Surg. 1993; 19:713–720.

18. Wang L, Hill WE, Koch DD. Evaluation of intraocular lens power prediction methods using the American Society of Cataract and Refractive Surgeons Post-Keratorefractive Intraocular Lens Power Calculator. J Cataract Refract Surg. 2010; 36:1466–1473.

19. Chen X, Yuan F, Wu L. Metaanalysis of intraocular lens power calculation after laser refractive surgery in myopic eyes. J Cataract Refract Surg. 2016; 42:163–170.

20. Abulafia A, Hill WE, Koch DD, et al. Accuracy of the Barrett True-K formula for intraocular lens power prediction after laser in situ keratomileusis or photorefractive keratectomy for myopia. J Cataract Refract Surg. 2016; 42:363–369.

21. Shammas HJ, Shammas MC. No-history method of intraocular lens power calculation for cataract surgery after myopic laser in situ keratomileusis. J Cataract Refract Surg. 2007; 33:31–36.