Focus on best outcomes when choosing epithelium debridement method for surface ablation
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Welcome to another edition of CEDARS/ASPENS Debates. CEDARS/ASPENS is a society of cornea, cataract and refractive surgery specialists, here to discuss some of the latest hot topics in ophthalmology.
Corneal refractive surgery continues to evolve. Yet, despite evolution of numerous new techniques, surface ablation remains a commonly used procedure, even after 25 years. Perhaps the one aspect of surface ablation that has evolved the most is the method for removal of the epithelium. This month, Inder Paul Singh, MD, and Gregg J. Berdy, MD, FACS, discuss their techniques for epithelial removal with surface ablation. We hope you enjoy the discussion.
Kenneth A. Beckman, MD, FACS
OSN CEDARS/ASPENS Debates Editor
Smoother stromal bed with alcohol
In general, there is no right or wrong method. This is not a one way or the other debate, but there are different options, and I have performed all during PRK.
I have performed mechanical, manual with the brush and used alcohol. I have even used a laser. Ultimately it will depend on the patient, but my routine method has been to use alcohol.
If you look at all of the data comparing mechanical, manual disruption or removal with alcohol, you will find in most of the published studies there are no differences between adverse events and outcomes. In fact, researchers have used electron microscopy to evaluate the smoothness of the stromal bed for all methods, and it has been shown that alcohol results in a smoother stromal bed with less skip area than even mechanical debridement. The smoother and more consistently even a stromal bed is for your laser, the better chance you will end up with an ideal ablation pattern.
For me, that is what changed my mind about alcohol. Additionally, it is an easier method in my hands compared with mechanical debridement. I believe it takes longer with a brush and can be more difficult to tell if the entire epithelium is removed and if it is truly consistent or clear. Alcohol is generally a quicker method and easier to confirm if the entire epithelium has been removed.
The ease of the procedure, the resulting consistency and the smoothness of the stromal bed make alcohol my go-to for the average PRK patient. In my experience, when you start to use a brush or when you use blades to clear up the epithelium, this can result in pitting of the stromal bed. If you have any lines, scratching or pitting on the stroma, that will affect the ablation.
The argument against alcohol is that it will cause more pain and discomfort and can leak. But the key to avoid all of these complications is to put enough pressure on the eye and enough force with the well on the cornea to keep the alcohol contained in the well. If you can do this, you will often avoid unnecessary pain and discomfort.
I use an 8-mm well during the procedure, and if enough pressure and force are exerted for 30 seconds, you can avoid leakage. I use a Weck-Cel sponge (BVI) to start to absorb the alcohol about 15 seconds before removing the well. If you have alcohol in the well while removing the well, it can spill around the eye and in the fornix and can lead to pain, injection, conjunctival edema and delayed healing postop.
I use the Weck-Cel sponge to first soak up the alcohol, making sure when I release the well there is no alcohol in it. I then quickly wash and irrigate with bottles of balanced salt solution to ensure there is no alcohol on the surface, debride the epithelium and finish the procedure.
If you do not soak up the alcohol before the well is removed, it will spill before you can irrigate the surface and flush it out. This will result in redness and a high amount of pain in your patients. If you do not use the alcohol correctly, your patients will experience this discomfort.
However, if alcohol is used correctly, this technique can limit pain and discomfort. Delayed healing has been reported, but in a study my late father and I conducted years ago, we found no differences in peeling time or discomfort when compared with mechanical debridement.
The bottom line is, there is no right or wrong way to complete this procedure. Do what is most convenient for you and what gives you the best outcomes for your patients.
- For more information:
- Inder Paul Singh, MD, can be reached at The Eye Centers of Racine and Kenosha, 3805B Spring St., Suite 140, Racine, WI 53405; email: inderspeak@gmail.com.
Faster healing with mechanical debridement
I began doing PRK in 1991 as one of the four principal investigators in St. Louis for the Visx FDA clinical trial. We performed only mechanical debridement during the trial.
As the procedure became standardized and approved, I continued to use mechanical debridement. Now, I will use a Tooke blade (ASICO) to perform the manual epithelium removal for the majority of my procedure. I also use an Amoils brush (Innovative Excimer Solutions), which is almost like a toothbrush, that you put on the surface to remove the epithelium.
The procedure has always worked well for me. I think I have good control of the procedure, and I can easily control my margins of epithelium removal. If you pay attention to what you are doing and just take off the epithelium, you will not damage any underlying structures.
This is not to say I have never tried alcohol removal. I have tried it; I used a small metal well filled with alcohol that was placed on the surface and used a Weck-Cel sponge (BVI) sponge to remove the alcohol. No matter how meticulous I was during the procedure, alcohol would invariably seep from underneath the well or roll over and spill onto the nontreated epithelial surface of the cornea and the epithelial surface of the conjunctiva.
Alcohol is epithelial toxic. Leaving it on for just seconds can damage the surface and ruin the integrity of the conjunctival epithelium, which in turn can decrease the secretion of goblet cells and alter the tear film. No matter what I did using alcohol, the epithelium never looked good. When the epithelial abrasion healed, it took longer in my mind than it did with mechanical removal.
One criticism of PRK, or what we now call advanced surface ablation, is that we break the integrity of the epithelial surface, and by the time it heals, patients can be uncomfortable. Some patients do not heal well, which leaves the patient open to possible infection and scarring of the cornea. I agree with all of that, but the sooner the epithelium heals, the less chance you have of that happening.
In my hands, I believe that the corneal epithelium has a more rapid healing time with manual removal than with alcohol removal. As a cornea and external disease specialist who treats lots of dry eye and ocular surface disease, the last thing I want to do is harm the ocular surface in any way. We are performing surgery, which is enough of an insult to the cornea, so I do not want to affect the integrity of the ocular surface or create additional problems.
Both methods are good treatments, and there are some people who love alcohol debridement. There was a time I did a surgery called LASEK, which was basically a PRK procedure that tried to preserve corneal epithelium and did not employ either a metal keratome or a femtosecond laser. A surgeon would place a well on the surface, add alcohol to loosen the epithelial attachment to the stroma, and then use an instrument that looked like a microscopic hoe to pull the epithelium back in one piece, like an accordion. The PRK would be performed, and then the surgeon would spread the epithelium back out intact to cover the laser-treated area.
What I found, and what many of my colleagues found, is the epithelium would typically slough off after 3 days. It was damaged from the alcohol exposure for that short 10 to 20 seconds. The patient would then be left with a large central abrasion.
The alcohol was not kind to the ocular surface, including areas where there was intact corneal and conjunctival epithelium. That cemented in my mind the negative aspect about using topical alcohol.
Most of us have used both methods, and it really is in the eye of the beholder and the hands of each individual surgeon. This is what matters. Look at your outcomes using both methods, and choose the procedure that gives you the best results.
- For more information:
- Gregg J. Berdy, MD, FACS, can be reached at Ophthalmology Associates, 12990 Manchester Road, Suite 200, St. Louis, MO 63131; email: gregg.berdy@youreyedoc.com.
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