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Transepithelial PRK leads to fast visual recovery less postoperative discomfort
Most patients were happy with results at 1 month after treatment.
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ABU DHABI — Transepithelial PRK with a laser leads to faster visual rehabilitation, less postoperative discomfort and no symptoms of erosion, according to a surgeon here.
Shady T. Awwad, MD, presented his early results with the Schwind Amaris at an industry symposium held at the World Ophthalmology Congress.
“I was skeptical initially. Then one of my colleagues convinced me to try it, and I had to admit that results were in many ways better compared to traditional PRK,” Dr. Awwad said. “From being a skeptic, I became an adopter, and now I am an advocate of this system.”
In a study, Dr. Awwad compared results of two groups of 70 eyes with similar baseline conditions treated with either traditional PRK or transepithelial PRK. Mean manifest refraction spherical equivalent was around –4.5 D in both groups, with a mean cylinder of 0.83 D in the traditional group and 0.68 D in the transepithelial group.
Refraction was effectively corrected with both treatments. However, patients in the transepithelial group reported significantly less postoperative discomfort in the first 3 days, particularly at day 2. Epithelial healing was quicker, taking an average of 2.6 days in the transepithelial group compared with 3.4 days in the traditional group. Visual recovery was also significantly faster in the transepithelial group.
After 1 month, 60% of the transepithelial patients were 20/20 compared with 43% of the traditional patients; 83% of the transepithelial patients were 20/25 compared with 66% in the traditional group.
“At 3 months, results were comparable, but to me it was nice to see that patients recovered faster,” Dr. Awwad said. “Another thing I want to mention is the consistency. Most patients improved at the same time, while with traditional PRK, there is a lot of interindividual variation. Some patients improve fast. Some take 3 or 4 months, and we have to hold them by the hand and explain to them that it will eventually get better. With transepithelial PRK, we have of course a couple of outliers, but the vast majority is happy by 1 month.”
In Dr. Awwad’s opinion, the inconsistent results with traditional PRK may be due to the differential humidity created on the eye surface by removal of the epithelium. With alcohol and even more with mechanical scraping, there are areas that are completely denuded and areas in which residual epithelium is present, leading to unequal stromal hydration.
Symptoms
Dr. Awwad found that symptoms of subclinical recurrent erosion are rare with transepithelial PRK.
“These symptoms typically manifest themselves as sharp pain and eyelid sticking to the eyeball, mainly in the morning upon awakening. They can go on for months and in some cases may require PTK treatment,” he said.
At 3 months, nearly 16% of the traditional PRK group reported pain symptoms, and 10% had sticking eyelids. In the transepithelial group, the percentages of these two symptoms were 1.4% and 1.8%, respectively.
“With regular PRK, the area of epithelium removal is larger than the zone treated by the laser. This untreated area is what I call the watershed annulus, and it’s typically here that erosion occurs,” Dr. Awwad said.
In the same area, epithelial erosion may occur after removal of the contact lens.
“In our study, 14% of the patients who had regular PRK called back or came back to the clinic a couple of days after contact lens removal with symptoms of erosion. This did not occur in any of the patients who had transepithelial PRK,” he said.
Limitations
With its many advantages, transepithelial PRK is a patient-friendly procedure, Dr. Awwad said.
“Also, take into consideration that patients like to know that it is a truly all-laser procedure, and this is a great marketing tool,” he said.
There are cases, however, in which the transepithelial approach is not suitable. In relatively thin corneas, in which ablation depth and optical zone diameter need to be strictly limited, the laser might end up performing a functional optical zone that is larger than desired. In corneas that have undergone previous refractive procedures, the epithelium profile will be different than expected, and this might lead to miscalculation. Also, low myopes with less than –2 D of error or low to moderate hyperopes should be excluded.
“Indication will broaden as the technology evolves. We are working at including OCT profiles and measurements of the epithelium for an even more accurate delivery of the treatment,” Dr. Awwad said. – by Michela Cimberle
For more information:
Shady T. Awwad, MD, can be reached at the American University of Beirut Medical Center, P.O. Box 11-0236, Beirut, Lebanon; email: sa11@aub.edu.lb.
Disclosure: Dr. Awwad has no relevant financial disclosures.
Perspective
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Michiel H.A. Luger, MD
As this study demonstrates, the downside of traditional surface ablation (PRK, LASEK, epi- LASIK) has been greatly reduced with the introduction of new ablation profiles by Schwind, allowing transepithelial refractive correction. The visual recovery is faster with less discomfort.By reducing the barriers for traditional surface ablation, the transepithelial approach has made PRK much more appealing to the patient. Being no-touch, the procedure is comfortable, there is less postoperative pain and the visual recovery process is shorter. Before transepithelial PRK, surface ablation was just an alternative option when patients did not qualify for LASIK. Now, it is frequently the primary choice of patients.
Long-term stability and effectiveness have been shown in studies with a follow-up of at least 1 year. However, longer follow-up is always helpful, and further studies on the variations in epithelial profiles would be useful to allow for customization in individual cases.
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