This procedure’s advance will revitalize refractive surgery, crosslinking.
While I am delighted with all the corneal topics covered in this month’s issue of Ophthalmology Management, I need to dive into detail about one: epi-Bowman keratectomy (EBK). It’s been a long time coming. I have been involved with EBK for several years, so when I heard Helen Wu, MD, speak about the latest advances in surface ablation, including EBK (page 22) at a conference, I invited her to write about it. I feel — as do many others — that this is the most significant breakthrough in surface ablation in many years, just as SMILE is to lamellar refractive laser surgery. Statistically-significant faster re-epithelialization occurs with EBK, with dramatically less pain and faster return of vision as well.
EBK involves the use of a disposable device with no moving parts. The surgeon holds a shaft with a polymeric tip at the end, which scoops up the corneal epithelium in strips and sheets, leaving an intact basement membrane and Bowman’s layer.
In well-designed, prospective randomized studies, the clinical results of EBK are superior to mechanical and laser-assisted epithelial removal techniques for both PRK and epi-off crosslinking.1-4 What is the explanation?
Theoretical advantage No. 1: As the epithelium is gently removed in strips and sheets, the fewest possible number of epithelial cells are ruptured, with the least amount of pro-inflammatory cytokines released into the stroma.
Theoretical advantage No. 2: Though basement membrane and Bowman’s layer are removed from the central cornea by the excimer laser, the basement membrane remains intact at the edge of the ablation, which facilitates its rapid reconstitution as the epithelial cells slide and divide their way centrally. Though transepithelial PRK offers this advantage as well, the first advantage — preserving as many intact epithelial cells as possible during the removal process — appears to offer the biggest clue as to why EBK was superior to laser scrape PRK in M. Taieb, MD’s study in Israel.3
It is entirely possible that there are other theoretical and real advantages to EBK that we have not yet envisioned or discovered.
Regarding epithelium-off crosslinking, Rohit Shetty, MD, of India provides ample evidence that EBK provides superior clinical results when compared to mechanical epithelial removal.4
EBK is now widely used internationally for both surface ablation and epithelium-off crosslinking. More recently, EBK has become a popular method for epithelial removal in the United States as well.
I believe that EBK and SMILE — both flap-free options — have the potential to revitalize the laser vision correction market in the United States and abroad. EBK will be used for lower refractive errors, and SMILE for higher refractive errors. Why this division? Since it is more challenging to completely remove the thinnest lenticules, SMILE will be performed for corrections above four diopters (though this problem may have been circumvented outside the United States by creating a plano correction in addition to the refractive lenticule, so that the total lenticule thickness is greater). EBK will be used for lower myopic corrections and for any patient needing astigmatic or hyperopic correction (until FDA approves SMILE for astigmatism and hyperopia). The next few months and years will tell the tale.
Dr. Wu’s article isn’t this issue’s only standout. First, we have discussions about the present and future of corneal crosslinking.
Another article looks at those surgeons who have taken the plunge into the corneal inlay arena and made them a success with patients.
Practice administrator Patti Barkey offers solutions for navigating prescription issues with dry eye patients.
And, I give some pointers on how to avoid obstacles when opening your own dry eye center. OM
- Shetty R, Nagaraja H, Pahuja NK, et al. Safety and efficacy of epi-Bowman keratectomy in photorefractive keratectomy and corneal collagen cross-linking: A pilot study. Current Eye Research. 2016;41:623-629.
- Mrukwa-Kominek E, Bubaa-Stachowicz B, Kucharzewski P, et al. Visual outcomes and quality of vision after Epithelial Bowman keratectomy as a method of myopia and myopic astigmatism correction. Poster presented at: 20th ESCRS Winter Meeting. Athens. Feb. 26-28, 2016.
- McDonald MB, Taieb M. Refractive nightmares. Presented at: America Academy of Ophthalmology 2015 Annual Meeting. Las Vegas: Nov. 14-17, 2015.
- McDonald MB, Shetty R. Refractive nightmares. Presented at: American Society of Cataract and Refractive Surgery, 2016 Annual Meeting. Boston: April 25-29, 2016.