Comparison of LASIK Mode Ablation and PRK Mode Ablation in LASEK Using MEL-80 Excimer Laser

Youngdon Kim; Damho Lee; Haksu Kyung

doi:10.3341/jkos.2014.55.11.1625

Journal List > J Korean Ophthalmol Soc > v.55(11) > 1009832

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Kim, Lee, and Kyung: Comparison of LASIK Mode Ablation and PRK Mode Ablation in LASEK Using MEL-80 Excimer Laser

Original Article

J Korean Ophthalmol Soc 2014;55(11):1625-1630.

Published online: 2 September 2014

DOI: https://doi.org/10.3341/jkos.2014.55.11.1625

Comparison of LASIK Mode Ablation and PRK Mode Ablation in LASEK Using MEL-80 Excimer Laser

Youngdon Kim, MD¹, Damho Lee, MD, PhD², Haksu Kyung, MD, PhD¹

¹Department of Ophthalmology, National Medical Center, Seoul, Korea

²Vision Eye Center, Seoul, Korea

Address reprint requests to Damho Lee, MD, PhD, Vision Eye Center, #867 Nonhyeon-ro, Gangnam-gu, Seoul 135-892, Korea, Tel: 82-2-548-3579, Fax: 82-2-540-1431, E-mail: damholee@naver.com

Received 28 September 2013 Revised 22 July 2014 Accepted 3 October 2014

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose

We compared laser assisted in situ keratomileusis (LASIK) mode and photorefractive keratectomy (PRK) mode ablation methods in laser subepithelial keratomileusis (LASEK) surgery using the MEL-80 excimer laser.

Methods

All patients were followed up for a minimum of 1 year. The PRK mode group consisted of 46 eyes of 23 patients and the LASIK mode group consisted of 97 eyes of 56 patients. The central corneal thickness (CCT), ablation thickness, manifest refractive error and uncorrected visual acuity were compared preoperatively, 1 month and 1 year postoperatively. Spherical equivalent (SE) of cycloplegic refraction at postoperative 1 month and the uncorrected visual acuity (UCVA) ratios of 1.0 or better at postoperative 1 year were compared between the two groups to evaluate clinical efficacy.

Results

The SE of refractive error, CCT and target corneal ablation thickness of the two groups were not significantly different preoperatively. The PRK mode group obtained an actual ablation mean thickness of 82.8% of the target and the LASIK mode group obtained an actual ablation mean thickness of 94.1% of the target at postoperative 1 month. In each group, a statistically significant difference was observed between the actual corneal ablation thickness and target corneal ablation thickness. In the PRK mode group, the mean SE of postoperative 1 month cycloplegic refraction was +0.24 ± 0.47 D and in the LASIK mode group, +0.87 ± 0.54 D, indicating a statistically significant difference between the two groups. One year postoperatively, the UCVA ratios of 1.0 or better were 83% in the PRK mode group and 96% in the LASIK mode group, showing a statistically significant difference between the two groups. However, SE of manifest refractive error and CCT in the two groups were not statistically different at postoperative 1 year.

Conclusions

The LASIK mode ablation method showed better results than the PRK mode ablation method in postoperative UCVA prognosis after LASEK surgery using the MEL-80 excimer laser.

Keywords: Corneal ablation thickness, LASEK, LASIK mode ablation, MEL-80 excimer laser

References

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Table 1.

Demographic data

	PRK mode	LASIK mode	p-value^∗
The number of subjects (eyes/patients)	46/23	97/56
Age (years)	30.3 ± 9.1	28.8 ± 7.8	0.315
Preoperative SE (diopter)	−4.21 ± 1.19	−4.04 ± 1.19	0.421
Preoperative CCT (μm)	540 ± 38	540 ± 33	0.980
Target corneal ablation thickness (μm)	87 ± 17	86 ± 6	0.780

Values are presented as mean ± SD.

PRK = photorefractive keratectomy; LASIK = laser assisted in situ keratomileusis; SE = spherical equivalent of cycloplegic refractive error;

CCT = central corneal thickness.

^∗ From the unpaired t-test.

Table 2.

Postoperative one month data

	PRK mode	LASIK mode	p-value^∗
Actual corneal ablation thickness (μm)	72 ± 19	81 ± 19	0.009
Difference between target & actual corneal ablation thickness (μm)	15 ± 12	6 ± 13	<0.001
CCT (μm)	469 ± 42	460 ± 35	0.19
SE (diopter)	+0.24 ± 0.47	+0.87 ± 0.54	<0.001

Values are presented as mean ± SD.

PRK = photorefractive keratectomy; LASIK = laser assisted in situ keratomileusis; CCT = central corneal thickness; SE = spherical equivalent of postoperative 1 month cycloplegic refractive error.

^∗ From the unpaired t-test.

Table 3.

Postoperative one month and one year data

		POD 1 month	POD 1 year
CCT (μm)	PRK mode group	469 ± 42	482 ± 40
	LASIK mode group	460 ± 35	475 ± 35
	p-value	0.19	0.30
MR (diopter)	PRK mode group	−0.10 ± 0.54	−0.35 ± 0.61
	LASIK mode group	−0.09 ± 0.86	−0.25 ± 0.65
	p-value	0.93	0.40
UCVA of 1.0 or better (%)	PRK mode group	−	83
	LASIK mode group	−	96
	p-value	−	0.02

Values are presented as mean ± SD.

POD = postoperative day; PRK = photorefractive keratectomy; CCT = central corneal thickness; MR = spherical equivalent of manifest refractive error; LASIK = laser assisted in situ keratomileusis; UCVA = uncorrected visual acuity.

Table 4.

The number of shots and target corneal ablation thickness according to refractive error presented by MEL-80 manufacturing company

Refractive error (diopter)	PRK mode (number of shots)	LASIK mode (number of shots)	Target corneal ablation thickness (μm)
-3	4052	4270	67
-5	5188	5606	92
-7	6302	6853	115
-9	7264	7947	137

PRK = photorefractive keratectomy; LASIK = laser assisted in situ keratomileusis.

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