Surface ablation again turns to laser

November 17, 2013

When asking the question, “What’s the ideal surface ablation: Laser, scraping, or alcohol?” it is not surprising that the response from Marguerite B. McDonald, MD, favors an approach known as Epi-Bowman Keratectomy (EBK).

New Orleans-When asking the question, “What’s the ideal surface ablation: Laser, scraping, or alcohol?” it is not surprising that the response from Marguerite B. McDonald, MD, favors an approach known as Epi-Bowman Keratectomy (EBK).           

Dr. McDonald said she has reviewed 50 articles outlining pros and cons for removing the epithelium during surface ablation.

“Most of the studies were [more than] 15 years old, small-series, and non-comparative,” said Dr. McDonald, clinical professor of ophthalmology, New York University Langone Medical Center.

Scrape came first, she said, and remains popular.

Low-tech, inexpensive, and effective, scraping’s negative effects are well-documented, she said, showing that even experienced surgeons leave behind basement cells and nests of epithelium cells, which can lead to irregular astigmatism.

It is also easy, Dr. McDonald said, to nick the stroma, again leading to irregular astigmatism and haze.

Alcohol is a popular method as well, because it is low-tech, inexpensive, effective, and faster than scraping-but not as fast as laser removal.

The peer-reviewed literature Dr. McDonald reviewed offered conflicting views: some studies report alcohol-treated eyes have a higher amount of postoperative pain, whereas other studies report less pain.

Laser removal is the fastest method, but requires skill and judgment because the epithelial layer differs in thickness across the cornea. This ablation produces the smallest epithelial defect possible, she said, and leaves a sharp edge to the epithelial defect, which most surgeons feel is desirable because it leads to faster epithelialization. 

But these early papers do not ask the right question, Dr. McDonald said. 

“The more gentle you are removing the epithelium, the quicker the patient will heal,” Dr. McDonald said, citing anecdotal evidence from both the United States and Israel.

The future lies in methods more like EBK, which removes the epithelium in layers without damaging Bowman’s layer.

Epithelial cell residue is collected within the tip in 8 to 10 seconds. 

In an ongoing clinical trial with the EBK by Tayeb Matzliah, MD, Israel, 95% of 50 eyes were completely healed within 72 hours.

There were zero reports of haze and zero enhancements.

What goes around comes back again, Dr. McDonald said, as surgeons discuss the best ways to debride the epithelium and minimize a painful, slow visual recovery.

 

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