Factors Associated with the Successful Separation of Corneal Epithelium in Epi-LASIK

Kyun-Hyung Kim; Joon-Heon Kim; Jong-Suk Song; Hyo-Myung Kim

doi:10.3341/jkos.2007.48.12.1623

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Kim, Kim, Song, and Kim: Factors Associated with the Successful Separation of Corneal Epithelium in Epi-LASIK

Original Article

J Korean Ophthalmol Soc 2007;48(12):1623-1629.

Published online: 30 August 2007

DOI: https://doi.org/10.3341/jkos.2007.48.12.1623

Factors Associated with the Successful Separation of Corneal Epithelium in Epi-LASIK

Kyun-Hyung Kim, M.D., Joon-Heon Kim, M.D., Jong-Suk Song, M.D. Ph.D., Hyo-Myung Kim, M.D. Ph.D.

Department of Ophthalmology, College of Medicine Korea University, Seoul, Korea

Address reprint requests to Hyo-Myung Kim, M.D. Ph.D., Department of Ophthalmology, Anam Hospital, College of Medicine, Korea University, #126-1 Anam-dong 5ga, Sungbuk-gu, Seoul 136-705, Korea, Tel: 82-2-920-5366, Fax: 82-2-924-6820, E-mail: hyomkim@kumc.or.kr

Received 27 February 2007 Accepted 14 August 2007

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

To determine the incidence and perioperative factors of flap-related complications from Epi-LASIK.

Methods

In this study, 122 eyes of 66 patients who had Epi-LASIK using Centurion SES^TM epikeratome (Norwood Eye Care, Australia) were enrolled. Associations of pre-operative corneal curvature, white-to-white distance, central corneal thickness, refractive error, dry eye, punctate corneal erosion, pannus, and history of wearing contact lenses with flap-related complications were investigated. To decrease flap-related complications, surgeons pressed patients’ eyelids with a speculum during epithelial separation, and the effect of this method was verified.

Results

Complete epithelial separation was achieved in 74 eyes (60.6%), incomplete separation in 29 eyes (23.8%), and free epithelial sheet in 19 eyes (15.6%). Thin corneas (P=.041), a history of wearing contact lenses (P=.008), and the duration of contact lens use (P=.003) significantly decreased the incidence of successful epithelial separation. Pressing down the eyelids with a speculum while separating the epithelial sheet increased the incidence of complete separation from 50.6% to 83.8% (P=.003).

Conclusions

The risk of flap-related complications from Epi-LASIK may be higher in people who use contact lenses and in people who have thin corneas. The risk can be reduced by pressing the eyelids with a speculum during epithelial separation.

Keywords: Epi-LASIK, Epithelial separation, Flap, Incomplete separation, Speculum

References

1. Duffey RJ, Leaming D. US trends in refractive surgery:2003 ISRS/AAO survey. J Refract Surg. 2005; 21:87–91.

2. Lee JB, Seong GJ, Lee JH, et al. Comparison of laser epithelial keratomileusis and photorefractive keratectomy for low to moderate myopia. J Cataract Refract Surg. 2001; 27:565–70.

3. Chen CC, Chang JH, Lee JB, et al. Human corneal epithelial cell viability and morphology after dilute alcohol exposure. Invest Iphthalmol Vis Sci. 2002; 43:2593–602.

4. Pallikaris IG, Katsanevaki VJ, Kalyvianaki MI, Naoumidi II. Advances in subepithelial excimer refractive surgery techniques: Epi-LASIK. Curr Opin Ophthalmol. 2003; 14:207–12.

5. Pallikaris IG, Kalyvianaki MI, Katsanevaki VJ, Ginis HS. Epi-LASIK:preliminary clinical results of an alternative surface ablation procedure. J Cataract Refract Surg. 2005; 31:879–85.

6. Azar DT, Ang RT, Lee JB, et al. Laser subepithelial keratomileusis: electron microscopy and visual outcomes of flap photorefractive keratectomy. Curr Opin Ophthalmol. 2001; 12:323–8.

7. Nichols KK, Nichols JJ, Mitchell L. The relation between tear film tests in patients with dry eye disease. Ophthalmic Physiol Opt. 2003; 23:553–60.

8. Kim JH, Oh CH, Song JS, Kim HM. Inadvertent stromal dissection during mechanical separation of the corneal epithelium using an epikeratome. J Cataract Refract Surg. 2006; 32:1759–63.

9. Matsumoto JC, Chu YS. Epi-LASIK update:overview of techniques and patient management. Int Ophthalmol Clin. 2006; 46:105–15.

10. Shah S, Sebai Sarhan AR, Doyle SJ, et al. The epithelial flap for photorefractive keratectomy. Br J Ophthalmol. 2001; 85:393–6.

11. Vesaluoma M, Perez-Santonja J, Petroll WM, et al. Corneal stromal changes induced by myopic LASIK. Invest Ophthalmol Vis Sci. 2000; 41:369–76.

12. Holden BA, Sweeney DF, Vannas A, et al. Effects of long-term extended contact lens wear on the human cornea. Invest Ophthalmol Vis Sci. 1985; 26:1489–501.

13. Vannas A, Holden BA, Makitie J. The ultrastructure of contact lens induced changes. Acta Ophthalmol. 1984; 62:320–33.

14. Bourne WM, Hodge DO, McLaren JW. Estimation of corneal endothelial pump function in long-term contact lens wearers. Invest Ophthalmol Vis Sci. 1999; 40:603–11.

15. Bruce AS, Brennan NA. Corneal pathophysiology with contact lens wear. Surv Ophthalmol. 1990; 35:25–58.

16. Liesegang TJ. Physiologic changes of the cornea with contact lens wear. CLAO J. 2002; 28:12–27.

17. Liu Z, Pflugfelder SC. The effects of long-term contact lens wear on corneal thickness, curvature, and surface regularity. Ophthalmology. 2000; 107:105–11.

18. Braun DA, Anderson Penno EE. Effect of contact lens wear on central corneal thickness measurements. J Cataract Refract Surg. 2003; 29:1319–22.

19. Madigan MC, Holden BA. Reduced epithelial adhesion after extended contact lens wear correlates with reduced hemidesmosome density in cat cornea. Invest Ophthalmol Vis Sci. 1992; 33:314–23.

Figure 1.

(A) Diagram of corneal surface to describe punctate erosion. The whole cornea was divided into 5 parts: superior, inferior, nasal, temporal, and central (4 mm in diameter in the center). (B) Diagram of the corneal surface to describe pannus.

The whole cornea was divided into 4 parts: superior, inferior, nasal, and temporal.

Figure 2.

(A) Normal orbital structure with speculum (arrow). (B) Changes after pressing down the eyelids. Increased mtraorbital pressure makes the eyeball to protrude and corneal curvature steeper.

Figure 3.

Hypothesis for incomplete separation. (A) In the early stage, the curvature of the cornea is so steep that it is enough to make counter-force against the separator. (B) In the middle stage, counter-force keeps up. (C) In the late stage, the curvature of the cornea flattens gradually and the decreased counter-force may cause incomplete separation.

Table 1.

Preoperative patients parameter and flap-related complications

Parameters	Mean (±SD)			P
Parameters	Complete flap	Incomplete flap	Free flap	P
No. of cases (%)	74 (60.6%)	29 (23.8%)	19 (15.6%)
Amount of ablation	-4.32±1.8D	-4.31± 1.5 D	-4.17±1.3D	.934
Corneal thickness	547±27 μm^†,‡	536±26 μm;^†	534±31 μm;^‡	.041^*
White-to-white distance	11.5±0.3 mm	11.5±0.4 mm	11.7±0.3 mm	.095
Corneal curvature (5 mm)	42.8± 1.4	43.2±1.5	42.2±1.9D	.079

^* Statistically significant. One-way ANOVA

^†,‡ The same symbols indicate significant difference between groups based on Tukey's multiple comparison test.

Table 2.

Dry eye and flap-related complications

Tearfilm break-up time (second)	Incidence (%)			Total
Tearfilm break-up time (second)	Complete flap	Incomplete flap	Free flap	Total
< 5	5 (62.5)	1 (12.5)	2 (25)	8
5- 9	8 (61.5)	3 (23.1)	2 (15.4)	13
10 ≤	61 (60.4)	25 (24.8)	15 (14.8)	101

Chi-square, P=.914

Table 3.

Punctate erosion and flap-related complications

Punctate erosion^*	Incidence (%)			Total
Punctate erosion^*	Complete flap	Incomplete flap	Free flap	Total
0	57 (58.2)	23 (23.5)	18 (18.3)	98
1	7 (58.4)	4 (33.3)	1 (8.3)	12
2	5 (71.4)	2 (28.6)	0 (0)	7
2 <	3 (60)	1 (20)	1 (20)	5

Chi-square, P=.857

^* Sum of each scale of five corneal regions (superior, inferior, nasal, temporal, and central) graded using a 0-4 scale.

Table 4.

Pannus and flap-related complications

Pannus^*	Incidence (%)			Total
Pannus^*	Complete flap	Incomplete flap	Free flap	Total
0	71 (60.2)	28 (23.7)	19 (16.1)	118
1	2 (66.7)	1 (33.3)	0 (0)	3
1 <	1 (100)	0 (0)	0 (0)	1

Chi-square, P=.866

^* Numbers of quadrant of corneal involvement.

Table 5.

Contact lens wear and flap-related complications

	Incidence (%)			Total	P
	Complete flap	Incomplete flap	Free flap	Total	P
Contact lens use
Non user	41 (75.9)	7 (13)	6 (11.1)	54	.008^*
user	33 (48.5)	22 (32.4)	13 (19.1)	68	.008^*
Type of contact lens
Soft contact lens	24 (47.1)	18 (35.3)	9 (17.6)	51	.648
Hard contact lens	9 (53)	4 (23.5)	4 (23.5)	17	.648

Chi-square

^* Statistically significant.

Table 6.

Pattern of contact lens wear and flap-related complications

Pattern	Mean±SD			P
Pattern	Complete flap	Incomplete flap	Free flap	P
Frequency of CL wear (day/week)	4.06±2.03	6.10±1.09	5.38±1.69	.133
Period of CL wear (year)	6.72±4.21	9.53±4.07^†	5.43±4.04^†	.003^*

^* Statistically significant. One-way ANOVA

^† The same symbols indicate significant difference between groups based on Tukey's multiple comparison test.

Table 7.

Eyeball protrusion method and flap-related complications

Method	Incidence (%)			Total
Method	Complete Incomplete	Free flap	flap flap	Total
Conventional method	43 (50.6%)	25 (29.4%)	17 (20.0%)	85
Eyeball protrusion method	31 (83.8%)	4 (10.8%)	2 (5.4%)	37

Chi-square, P= .003

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