A look at the resurgence of surface ablation

Surface ablation is making a comeback. Here’s why.

Removal of the epithelium for
surface ablation using an Amoil's
brush and alcohol.

Scraping of the epithelium
for surface ablation.
Source: Steven C. Schallhorn, M.D.

For a while, it looked like surface ablation was all but dead, with practitioners favoring its more marketing-friendly relation — LASIK. But recently, surface ablation has gained steam, with many practitioners once again offering this option to their patients.
Steven C. Schallhorn, M.D., director of cornea and refractive surgery, Naval Medical Center, San Diego, who continued to perform PRK at a time when others shunned the procedure, has found himself with a lot more company of late.
“Five years ago, I was almost a lone voice saying surface ablation has a lot to offer — it’s a very viable procedure,” Dr. Schallhorn said. “Many physicians downplayed surface ablation years ago. It’s re-emerging now because there are a lot of patients that are better served with surface ablation compared to LASIK.”

Renewed interest

Richard L. Lindstrom, M.D., clinical professor of ophthalmology, University of Minnesota, Minneapolis, has also seen a rekindling of interest in surface ablation. He now does selective surface ablation in about 10% of patients.
A few years ago, he only performed LASIK. He now believes that surface ablation remains a valid option for several reasons.
“The asset of surface ablation is that it removes tissue less deeply in the cornea and appears to have less of a tendency to induce ectasia,” Dr. Lindstrom said.
So, particularly for patients that make practitioners nervous about the possibility of ectasia, such as those that have thin corneas or those with non-orthogonal astigmatism, asymmetric bow ties, or unusual looking corneas, surface ablation can be a compelling option.
Some practitioners also opt for surface ablation because they believe that the resultant quality of vision is superior to that obtained via LASIK.
“There are surgeons that have abandoned LASIK in favor of surface ablation because they think that it gives a better visual acuity outcome,” Dr. Lindstrom said.
A third factor tipping the scales for some is complication rates.
“They each have potential complications, but for some surgeons, the complication rate with LASIK is higher than they’re comfortable with,” Dr. Lindstrom said. “There are some surgeons that aren’t comfortable facing the chance of potentially sight-threatening complications from bad flaps, slipped flaps, diffuse lamellar keratitis, and epithelial ingrowth, and that now favor surface ablation for that reason.”

Selecting surface patients

For most surgeons, determining which patients to offer surface ablation to is a balancing act.
“The obvious candidates are patients that have thinner corneas that are on the edge of having too little tissue remaining after a LASIK procedure” Dr. Schallhorn said. In a case where a physician chooses between using a small optical zone for treatment to preserve tissue for LASIK or going to the surface and using a standard optical zone, the latter makes sense, Dr. Schallhorn said.
He also favors surface ablation for patients that have epithelial basement membrane dystrophy, where they are more likely to have an epithelial defect as a result of a LASIK procedure, as well as for those with topographic anomalies.
“Patients would probably be better served with surface ablation if there’s an issue or question about problems that would likely arise because of LASIK,” Dr. Schallhorn said.

Avoiding the downside of surface ablation

While surface ablation has gained popularity, it still has its weaknesses, not the least of which is the discomfort that can accompany the procedure. Over the years, Dr. Schallhorn has fine-tuned his approach to handling discomfort after PRK.
“We chill the cornea with a “popsicle” (a moistened then frozen non-fragmenting sponge, as suggested by Daniel S. Durrie M.D., Overland Park, Kan.) applied for a few seconds immediately after surgery, provide the patients topical, non-preserved, tetracaine, use an ultra-high Dk bandage contact lens (Ciba Vision, Duluth, Ga.), and then monitor the patients closely in the early post-op time period,” he said. “We also give them an oral non-steroidal, ibuprofen, and a break-through oral narcotic medication.”
To avoid the pain of surface ablation, Dr. Lindstrom favors using cold BSS on the eye at the end of the procedure. He then puts a bandage contact lens on and gives the patient a non-steroidal anti-inflammatory medication to use four times a day.
“Right now I’m an Acular LS (Allergan, Irvine, Calif.) user. I tell them to use that as long as it hurts,” Dr. Lindstrom said. He also gives patients tetracaine (Alcon, Fort Worth, Texas) to use.
“I tell them that they can use it every hour for breakthrough pain,” he said. “There’s good evidence to suggest that in spite of what we have been taught, that up to a week of topical anesthetic does not interfere with epithelial wound healing.”
He also gives patients prescriptions for Vicodin (hydrocodone bitratrate, acetaminophen, Abbott Laboratories, Abbott Park, Ill.), to use when needed.
Another bugaboo with surface ablation is concern about haze.
“Everyone raises the issue of haze as the reason not to perform surface ablation, but the incidence is actually very low, and if it does occur, it can be appropriately managed,” Dr. Schallhorn said. He finds that haze often clears with a trial of steroid drops.
In cases where the haze is persistent, visually significant, and a trial of topical steroids has not helped, Dr. Schallhorn recommends mitomycin-C (MMC).
“We remove the epithelium and apply 0.02% mm for two minutes on a 6mm circular sponge, then copious irrigation,” he said. For prophylactic use in higher myopes, he recommends using 0.01% MMC for one minute.
“Think of it this way — managing haze after PRK is easier than managing ectasia after LASIK,” Schallhorn said.
Dr. Lindstrom likewise uses MMC prophylactically for higher myopes.
“When I first started, I followed the…dictum of two minutes of 0.2 mg per mL with copious irrigation,” he said. “We’re now down to 12 seconds.”
So far with this approach, Dr. Lindstrom has not seen any sight-threatening complications. There have been a few cases of haze recurrence, but only in deep PRKs in extreme myopes that had developed haze in the past.
Overall, surface ablation has become a more competitive alternative to LASIK than in the past.
In the end, in most cases, deciding which procedure to use will come down to practitioner prerogative, he said.

Editors’ note: Dr. Lindstrom is a consultant for Alcon, Advanced Medical Optics (Santa Ana, Calif.) and Bausch & Lomb (Rochester, N.Y.). Dr. Schallhorn has no related professional affiliations.

Contact Information
Lindstrom: 612-813-3633, rllindstrom@mneye.com
Schallhorn: 619-532-6702, Scschallhorn@nmcsd.med.navy.mil