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

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

• Kim KH
• Kim JH
• Song JS
• Kim HM

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.

Keyword

Epi-LASIK; Epithelial separation; Flap; Incomplete separation; Speculum

MeSH Terms

Contact Lenses
Cornea
Epithelium, Corneal*
Eyelids
Humans
Incidence
Refractive Errors
Surgical Instruments

Figure

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  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.

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  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.

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  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.

Reference

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