Femtosecond phenomenon: Burgeoning alternative applications
Femtosecond phenomenon: Burgeoning alternative applications
Considering new possibilities for femtosecond technology from lenticule extraction to etching flaps with the femtosecond laser and more, this technology is making inroads in many areas of ophthalmology, according to Ginny L. Kullman, M.D., assistant professor, Ochsner Medical Center, New Orleans. In the September-November 2010 issue of Seminars in Ophthalmology, Dr. Kullman, together with Roberto Pineda, M.D., assistant professor of ophthalmology, Harvard Medical School, Boston, and director of refractive surgery, Massachusetts Eye and Ear Infirmary, Boston, reviewed the latest advances in this area.
“I was doing my fellowship at Massachusetts Eye and Ear and we had a research core review project —the topic was technological advances in the field of ophthalmology,” Dr. Kullman said. “I wanted to target it more to cornea as I was doing a cornea fellowship.” Dr. Kullman felt that there was a lot of burgeoning interest in the femtosecond laser, which she was intrigued by, and she had just done a femtosecond corneal tattooing procedure with Dr. Pineda—something that she saw as a novel technique. Spurred by this, she decided to review the latest alternative applications for the femtosecond laser.
Traditionally, the femtosecond laser has been used in the refractive arena. “It was originally approved for refractive surgery and cutting LASIK flaps,” Dr. Kullman said. “It had a secondary indication for the implantation of the intracorneal rings.” Interest has since expanded into indications running the gamut from cataract to retina.
Broadening applications
Dr. Kullman found that use of the femtosecond laser for cataract surgery was one of the leading areas of interest. “There are a lot of femtosecond lasers under study for the different stages of cataract surgery,” she said.
The femtosecond technology can help in a number of ways. “We can use the femtosecond laser for anterior capsulotomy, lens fragmentation, the main cataract incision, and if there's any astigmatism, that can be addressed as well,” Dr. Kullman said. “The idea is that we can specifically determine the size, shape, and diameter of the capsulorhexis, which is important for centering the accommodating and premium IOLs for the refractive outcome of those lenses.” The hope is that the femtosecond laser will improve visual outcomes for those patients desiring premium or accommodating lenses.
In the refractive surgery domain, Dr. Kullman found that there are a lot of novel techniques that are being investigated. “One is the FLEx [femtosecond lenticular extraction] procedure, which is refractive laser surgery, but it obviates the need for the excimer laser,” she said. “It's all done with the femtosecond laser, and we produce an intrastromal lenticule that's extracted either with the hinge, which is the FLEx procedure, or without the hinge through a small incision, which is called small-incision lenticule extraction, or SMILE.” These two techniques are basically the same with a slight variation in the incision used to remove the lenticule. “You don't have the full side cut for the SMILE incision,” Dr. Kullman said. “For those patients it's the bladeless laser.”
Work in the initial FLEx trials was targeted at those with very low myopia. “It didn't have an exact nomogram designed, but I think the more patients that they experiment on, the more reproducible results can be,” Dr. Kullman said.
In addition, investigators considered an intrastromal technique to correct presbyopia, which involved using the laser to deliver some intrastromal circumferential cuts. “This is interesting because we're not creating a flap, and there's no tissue being removed,” Dr. Kullman said. “By shifting the biomechanics of the cornea, the idea is that we can improve near vision.”
The group targeted for study here were emmetropic patients of presbyopic age. Results with the technique showed that patients' near vision improved, but there was a downside. “Unfortunately, for some of the patients, their distance vision dropped a few lines, so it's a tradeoff,” Dr. Kullman said. “But there's no pain and no risk of infection.”
Future possibilities
Dr. Kullman thinks that one of the newer applications is going to be implementing the femtosecond laser for lamellar keratoplasty surgeries. “Anterior lamellar keratoplasty is pretty straightforward because we're not going very deep and just removing the top 100 or 200 microns of cornea,” she said. “Posterior lamellar surgery is still relatively novel as far as how deep we can go with the laser, but I think that they're trying to prepare tissue for DSEK surgeries now with the femtosecond laser.” On the downside, there are concerns about endothelial cell loss, and there can be a learning curve. Even so, Dr. Kullman is optimistic.
Another possible application of the femtosecond laser may be in conjunction with collagen crosslinking. “Classically when we create a corneal ablation, we remove the epithelium and apply the riboflavin and the UV [ultraviolet] light,” Dr. Kullman said. “We found one study looking at making a flap [with the femtosecond laser] without lifting it, injecting the riboflavin into the flap, and treating the UV flap on an intact epithelium.” Patients were followed for 26 months. “There was stabilization of the keratometry readings, and for some patients [these readings] even decreased,” Dr. Kullman said.
Overall, Dr. Kullman thinks that there's a lot of exciting femtosecond technology on the horizon. However, she pointed out that there are still some logistics that need to be addressed. “I'm imagining doing cataract surgery with a laser and logistically how that would work with transporting a patient from the laser to the OR suite or if it's possible to put the laser in the OR suite,” Dr. Kullman said. “If we can get around those issues, I think that it's very promising and exciting for a certain subset of patients.” EW
Editors' note: Dr. Kullman has no financial interests related to her comments.
Contact information
Kullman: 508-842-3995, gkullman@ochsner.org
by Maxine Lipner Senior EyeWorld Contributing Editor
Considering new possibilities for femtosecond technology from lenticule extraction to etching flaps with the femtosecond laser and more, this technology is making inroads in many areas of ophthalmology, according to Ginny L. Kullman, M.D., assistant professor, Ochsner Medical Center, New Orleans. In the September-November 2010 issue of Seminars in Ophthalmology, Dr. Kullman, together with Roberto Pineda, M.D., assistant professor of ophthalmology, Harvard Medical School, Boston, and director of refractive surgery, Massachusetts Eye and Ear Infirmary, Boston, reviewed the latest advances in this area.
“I was doing my fellowship at Massachusetts Eye and Ear and we had a research core review project —the topic was technological advances in the field of ophthalmology,” Dr. Kullman said. “I wanted to target it more to cornea as I was doing a cornea fellowship.” Dr. Kullman felt that there was a lot of burgeoning interest in the femtosecond laser, which she was intrigued by, and she had just done a femtosecond corneal tattooing procedure with Dr. Pineda—something that she saw as a novel technique. Spurred by this, she decided to review the latest alternative applications for the femtosecond laser.
Traditionally, the femtosecond laser has been used in the refractive arena. “It was originally approved for refractive surgery and cutting LASIK flaps,” Dr. Kullman said. “It had a secondary indication for the implantation of the intracorneal rings.” Interest has since expanded into indications running the gamut from cataract to retina.
Broadening applications
Dr. Kullman found that use of the femtosecond laser for cataract surgery was one of the leading areas of interest. “There are a lot of femtosecond lasers under study for the different stages of cataract surgery,” she said.
The femtosecond technology can help in a number of ways. “We can use the femtosecond laser for anterior capsulotomy, lens fragmentation, the main cataract incision, and if there's any astigmatism, that can be addressed as well,” Dr. Kullman said. “The idea is that we can specifically determine the size, shape, and diameter of the capsulorhexis, which is important for centering the accommodating and premium IOLs for the refractive outcome of those lenses.” The hope is that the femtosecond laser will improve visual outcomes for those patients desiring premium or accommodating lenses.
In the refractive surgery domain, Dr. Kullman found that there are a lot of novel techniques that are being investigated. “One is the FLEx [femtosecond lenticular extraction] procedure, which is refractive laser surgery, but it obviates the need for the excimer laser,” she said. “It's all done with the femtosecond laser, and we produce an intrastromal lenticule that's extracted either with the hinge, which is the FLEx procedure, or without the hinge through a small incision, which is called small-incision lenticule extraction, or SMILE.” These two techniques are basically the same with a slight variation in the incision used to remove the lenticule. “You don't have the full side cut for the SMILE incision,” Dr. Kullman said. “For those patients it's the bladeless laser.”
Work in the initial FLEx trials was targeted at those with very low myopia. “It didn't have an exact nomogram designed, but I think the more patients that they experiment on, the more reproducible results can be,” Dr. Kullman said.
In addition, investigators considered an intrastromal technique to correct presbyopia, which involved using the laser to deliver some intrastromal circumferential cuts. “This is interesting because we're not creating a flap, and there's no tissue being removed,” Dr. Kullman said. “By shifting the biomechanics of the cornea, the idea is that we can improve near vision.”
The group targeted for study here were emmetropic patients of presbyopic age. Results with the technique showed that patients' near vision improved, but there was a downside. “Unfortunately, for some of the patients, their distance vision dropped a few lines, so it's a tradeoff,” Dr. Kullman said. “But there's no pain and no risk of infection.”
Future possibilities
Dr. Kullman thinks that one of the newer applications is going to be implementing the femtosecond laser for lamellar keratoplasty surgeries. “Anterior lamellar keratoplasty is pretty straightforward because we're not going very deep and just removing the top 100 or 200 microns of cornea,” she said. “Posterior lamellar surgery is still relatively novel as far as how deep we can go with the laser, but I think that they're trying to prepare tissue for DSEK surgeries now with the femtosecond laser.” On the downside, there are concerns about endothelial cell loss, and there can be a learning curve. Even so, Dr. Kullman is optimistic.
Another possible application of the femtosecond laser may be in conjunction with collagen crosslinking. “Classically when we create a corneal ablation, we remove the epithelium and apply the riboflavin and the UV [ultraviolet] light,” Dr. Kullman said. “We found one study looking at making a flap [with the femtosecond laser] without lifting it, injecting the riboflavin into the flap, and treating the UV flap on an intact epithelium.” Patients were followed for 26 months. “There was stabilization of the keratometry readings, and for some patients [these readings] even decreased,” Dr. Kullman said.
Overall, Dr. Kullman thinks that there's a lot of exciting femtosecond technology on the horizon. However, she pointed out that there are still some logistics that need to be addressed. “I'm imagining doing cataract surgery with a laser and logistically how that would work with transporting a patient from the laser to the OR suite or if it's possible to put the laser in the OR suite,” Dr. Kullman said. “If we can get around those issues, I think that it's very promising and exciting for a certain subset of patients.” EW
Editors' note: Dr. Kullman has no financial interests related to her comments.
Contact information
Kullman: 508-842-3995, gkullman@ochsner.org
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