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Transepithelial PRK corrects long-term effects of radial keratotomy
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Transepithelial PRK with application of mitomycin C can treat refractive instability after radial keratotomy, according to a study.
In two hospitals in Iran, 22 eyes of 22 consecutive patients who had undergone RK 17 to 22 years previously, with refractive error stable for at least 1 year, transepithelial PRK was performed. Based on topography, wavefront and refractive data, the epithelium and stroma were ablated in a single step using the corneal wavefront-guided transepithelial PRK nomogram of the Schwind Amaris 1050RS laser. Immediately after, MMC was applied to the stromal bed for 30 to 40 seconds, followed by balanced salt solution irrigation.
At 6 months, mean cylinder decreased, although not significantly. Mean higher-order aberrations, spherical aberration and coma were significantly reduced. Mean uncorrected distance visual acuity improved, and corrected distance visual acuity improved or remained stable in most eyes, with one eye losing two lines and two eyes losing one line.
The correction of post-RK refractive error has shown limited success with all procedures. Due to the irregularity of the corneal surface, PRK is usually associated with regression and haze. The authors explained that in the transepithelial approach, the epithelium acts as a natural mask, thinning over stromal protrusions and thickening over dips, leading to maximum correspondence between topography and ablation. In addition, MMC effectively prevents haze formation, as shown by the study.
“Transepithelial PRK might prove to be a promising and effective procedure in treating residual aberration and refractive error,” the authors said. “Large, prospective and comparative studies are required to show the efficacy of transepithelial PRK in comparison to several refractive surgeries for post-RK patients.”
“In clinical practice, there are few surgical options for these patients. The results of LASIK, conventional or customized PRK are guarded due to high corneal irregularity and technical difficulties,” one of the study authors, Nima Koosha, MD, told Healio.com/OSN. “With combining topo-guided and transepithelial PRK, the epithelium serves as a masking device and topo-guided ablation corrects both low- and higher-order aberrations. According to our study, both visual aberrometric results were very good and safety index was high, as there were no significant complications such as haze formation.” – by Michela Cimberle
Disclosures: The authors report no relevant financial disclosures.
Perspective
Back to TopMassimo Camellin, MD
Transepithelial PRK is the safest option to correct any refractive error following incisional surgery. The procedure is quite easy but requires a particular platform (Schwind Amaris). Results are not always perfect in all cases, but it is possible to perform further enhancements.
We are facing now some of the long-term consequences of RK. Patients are experiencing a significant hyperopic shift, and because most of them are about 50 years old, this adds up to the sight problems caused by presbyopia. By treating their astigmatism and hyperopia, we can significantly reduce their discomfort.
I have more than 15 years of personal experience with this approach, with more than 600 treated cases. The first results I published have been confirmed over the years, and I continue to perform this customized surgery in a lot of old RK patients. Only in a few specific cases, where the incisions are very ectatic, they need stitches, and very rarely, we have to perform corneal transplantation.
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