J Korean Ophthalmol Soc.  2010 Sep;51(9):1196-1202. 10.3341/jkos.2010.51.9.1196.

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

• Ahn JM
• Ahn HS
• Seo KY
• Kim EK
• Kim TI

• KMID: 2122285
• DOI: http://doi.org/10.3341/jkos.2010.51.9.1196

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.

Keyword

iTrace aberrometer; Nomogram; Postcycloplegic refraction; Wavefront-guided LASEK; Wavescan

MeSH Terms

Humans
Keratectomy, Subepithelial, Laser-Assisted
Medical Records
Nomograms
Refractive Errors

Figure

• 

  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.

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  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.

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  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.

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