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Epithelium integral in refractive surgery outcomes, surgeon says
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ALICANTE, Spain — The corneal epithelium plays a critical role in modulating healing after refractive surgical procedures, and taking steps to address epithelial ingrowth is important to preventing poor visual outcomes, according to a surgeon speaking here.
"When you make large abrasions in the corneal epithelium, you get three to six sheets of cells moving from the periphery to the center," said Harminder S. Dua, MD, of Nottingham University, England, at the Alicante Refractiva International meeting. "When they meet, the lines of contact between [the cells], which [when] stained with fluorescein look like dendritic figures, affect vision."
Such irregularities will eventually disappear, and only then will patients recover their full potential visual function, he said.
Dr. Dua noted that LASEK represents a good example of this process because the short-term outcomes vary according to the conditions of the epithelial flap.
"If you have a damaged epithelial flap, which is no longer viable, and you put it back into place, there will be a new epithelial layer growing underneath it. The two layers of epithelium will compete with each other, and until the new healthy epithelium takes over and the damaged, more superficial layer falls off, vision will remain poor," Dr. Dua said.
Conversely, if the flap is healthy, recovery is faster because the healthy flap prevents keratocyte activation. There is little haze and the patient's vision improves within 3 days after surgery, he said.
Epithelial ingrowth may also develop under a LASIK flap when there is a discrepancy between the flap and the underlying stromal bed. In particular, the risk is highest after LASIK re-treatments, he noted.
"This happens particularly when, to re-lift the flap, the surgeon makes a small opening and peels it off," he said. Such maneuvers often lead to epithelial tearing and abrasion, which triggers a chain of healing processes and consequent epithelial ingrowth, he said.
To avoid this, Dr. Dua suggested cutting along the previous LASIK flap edge using a fine needle before lifting the flap.
"By doing this, I have a zero rate of epithelial ingrowth following LASIK enhancement," he said.