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Ahn, Ahn, Seo, Kim, and Kim: Comparison of the Refractive Error Measurement Using Different Methods in Wavefront-Guided LASEK
Original Article
Journal of the Korean Ophthalmological Society

Journal of the Korean Ophthalmological Society 2010; 51(9): 1196-1202.

Published online: 30 September 2010

DOI: https://doi.org/10.3341/jkos.2010.51.9.1196

Comparison of the Refractive Error Measurement Using Different Methods in Wavefront-Guided LASEK

Ji Min Ahn, MD1, 2, Hyun Seok Ahn, MD1, Kyoung Yul Seo, MD, PhD1, Eung Kweon Kim, MD, PhD1, Tae Im Kim, MD, PhD1

1The Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea.

2Siloam Eye Hospital, Seoul, Korea.

Address reprint requests to Tae Im Kim, MD, PhD. Department of Ophthalmology, Yonsei University Severance Hospital, #134 Sinchon-dong, Seodaemun-gu, Seoul 120-752, Korea. Tel: 82-2-2228-3570, Fax: 82-2-312-0541, tikim@yuhs.ac

Received 6 January 2010       Accepted 7 July 2010

Copyright © 2010 The Korean Ophthalmological Society

Abstract

Purpose

To predict the accuracy of preoperative refractive error measurement methods in wavefront-guided laser-assisted subepithelial keratectomy (LASEK) surgery and to formulate a nomogram for satisfactory surgical results.

Methods

The medical records of 30 patients (57 eyes) who had undergone wavefront-guided LASEK were reviewed. The ideal surgical ablation amount was defined as the sum of the real surgical ablation amount and the remaining refractive errors. Comparison between the ideal surgical ablation amount and preoperative refractive errors was made using autorefraction, manifest refraction, cycloplegic refraction, postcycloplegic refraction, wavescan, and iTrace aberrometer measurements.

Results

The refractive errors measured by the postcycloplegic refraction showed the closest relation with the ideal surgical amount, and the nomogram based on this refraction correlated statistically significantly with the ideal surgical ablation amount. The refractive error using the wavescan also showed more accurate refractive measurements than the autorefractor and iTrace aberrometer.

Conclusions

Accurate manifest refraction immediately before surgery is the most important in determining the ablation amount. Additionally, the refractive errors measured with the wavescan, which is an aberrometer used for wavefront-guided LASEK, showed a minimal amount of errors. After reviewing the results, the nomogram based on these 2 methods can be concluded to possibly contribute to an increase in the accuracy of surgery.

Keywords: iTrace aberrometer, Nomogram, Postcycloplegic refraction, Wavefront-guided LASEK, Wavescan

Figures and Tables

Figure 1
Correlation and correlation coefficient between postcycloplegic refractive error and ideal surgical ablation amount. (A)Sphere. (B) Cylinder. D=diopters; PC=postcycloplegic refraction; sph=sphere; cyl=cylinder.
jkos-51-1196-g001
Figure 2
The differences between residual spherical refractive errors after ablation and preoperative refractive errors using various methods. These graphs are showing the distribution of the residual spherical refractive errors for each of all patients. The residual refractive error is defined as the value of the amount of the ideal surgical ablation minus the preoperative refractive errors measuring with various methods. D=diopters; AR=autorefraction; MR=manifest refraction; CR=cycloplegic refraction; PC=postcycloplegic refraction.
jkos-51-1196-g002
Figure 3
The differences between residual cylindrical refractive error after ablation and preoperative refractive errors using various methods. These graphs are showing the distribution of the residual cylindrical refractive errors for each of all patients. The residual refractive error is defined as the value of the amount of the ideal surgical ablation minus the preoperative refractive errors measuring with various methods. D=diopters; AR=autorefraction; MR=manifest refraction; CR=cycloplegic refraction; PC=postcycloplegic refraction.
jkos-51-1196-g003
Table 1
Measurement of preoperative refractive error using variable methods and postoperative refractive error
jkos-51-1196-i001

*SE=spherical equivalent.

Table 2
Correlation between refractive errors obtained with preoperative evaluation test and ideal surgical ablation amount
jkos-51-1196-i002

*ICC=intraclass correlation coefficient; †SE=spherical equivalent; ‡AR=autorefraction; §MR=manifest refraction; ∥CR=cycloplegic refraction; #PC=postcycloplegic refraction.

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