June 2016




Femtosecond laser flap creation in prior RK patients

by Maxine Lipner EyeWorld Senior Contributing Writer


Now a lot of us have hung the microkeratome on the shelf, and we feel a lot more comfortable using the femtosecond laser. Sloan Rush, MD

Femtosecond laser

Some practitioners are hesitant to create a LASIK flap with a femtosecond laser in prior RK patients. Source: John Berdahl, MD

Femtosecond LASIKA recent study found that femtosecond LASIK can be a viable option for prior RK patients.

Source: Uday Devgan, MD

Study results indicate there is no need to forego femtosecond LASIK in such patients

Aprior radial keratotomy (RK) usually makes practitioners think twice about creating a LASIK flap with a femtosecond laser. But study results published in the September/October 2015 issue of the Asia-Pacific Journal of Ophthalmology point to the fact that the femtosecond laser can be a viable option, according to Sloan Rush, MD, in private practice, Amarillo, Texas. The results indicated that LASIK flaps were able to be successfully created in 100% of the post-RK patients who were included here, he reported.

The investigation was spurred by the fact that many of the patients who underwent RK in the late 1980s and 1990s are now in a situation ripe for retreatment. As we know, many of our RK patients develop hyperopic regression, so they come back to us years later. Some of them are now in their late 40s and others in their early 50s, Dr. Rush said. Such individuals are seeking additional refractive treatment because they are now becoming presbyopic and the hyperopic refraction with which they are living has become problematic. While they may have been able to accommodate through this in the past, with the beginning of presbyopia, that is no longer possible, and they want something else done, he explained. Ideally, we dont want to offer them a refractive lensectomy, especially if there is no cataract there, Dr. Rush said. In my center we prefer not to do PRK because we know in our hands were better with LASIK, and PRK can have healing problems and take longer to recover from. Dr. Rushs top choice is LASIK, assuming that he can create a safe and successful flap.

Femtosecond RK dilemmas

While traditionally a manual microkeratome has been successfully used, some practitioners have moved away from these. Now a lot of usmyself includedhave hung the microkeratome on the shelf, and we feel a lot more comfortable using the femtosecond laser, Dr. Rush said. We like the flexibility it gives us with controlling the flap depth and the diameter. The problem in RK patients is that the femtosecond flap doesnt just lift open; it leaves little stromal bridges that have to be broken apart by an instrument, he explained, adding that in the RK patient, the prior incisions can sometimes be more fragile than the perforated edge left by the femtosecond laser. The result can be what appears to be an 8-slice pizza pie-like flap, Dr. Rush said. There is also concern about evacuation of the air bubbles left by the femtosecond laser, with the worry that in certain circumstances there may be vertical gas breakthrough via an old RK incision. You open a whole can of worms for potential complications with epithelial ingrowth or an unstable flap or irregularity when you try to lift it and 1 of the incisions is filleted open, Dr. Rush said.

However, he has experimented with many different femtosecond laser settings, trying to modulate the way it cuts the flap. Through our experience, we are aware of settings where we can cut a femtosecond flap and leave no tissue bridges behindwhere it cuts completely clean all of the way through, Dr. Rush said. This is an ideal setting to have when you have a previous RK eye, so you dont have to worry about spreading open the incision. He finds that it then lifts more like a manual microkeratome flap would, with no resistance. Included in the retrospective consecutive chart review study were 16 eyes of 8 subjects with hyperopia after RK who had undergone femtosecond laser-assisted LASIK. When each of these patients was treated, femtosecond power was increased and more spots placed to make it easier to lift the flap, Dr. Rush reported. In all cases the femtosecond flap was successfully created. We didnt have any cases of vertical gas breakthrough or epithelial ingrowth. Our refractive outcomes were similar to what you would expect to see in a virgin eye.

Clinical possibilities

Dr. Rush is hopeful about what this means clinically. Just by modulating the settings, we can come up with a good approach to offer patients the great outcomes of LASIK rather than resorting to another refractive technique like PRK or doing another surgery altogether like a refractive lensectomy, he said.

For those looking to create femtosecond flaps for such patients, Dr. Rush advised making these as deep as possible. That adds more structural integrity to the flap, and it makes it less likely to open up in an RK incision, he said. In addition, the power setting is key because you dont want any tissue bridges remaining when you lift the flap.

If there are any issues with the flap, Dr. Rush stressed the need for caution. If ever an RK incision is open or you get vertical gas breakthrough, we dont recommend proceeding with the treatment because we think its a big risk for developing epithelial ingrowth, he said. If the flap doesnt seem to cut right, he urged practitioners to refrain from trying to lift this. Overall, Dr. Rush hopes that practitioners come away from the study with the understanding that there is no need to forego femtosecond LASIK in such patients and instead offer them premature lens exchange with riskier, invasive surgery. With this study, we have shown that we can offer them something less invasive, give them good outcomes, and avoid having to do cataract surgery prematurely, he concluded.


Rush SW, et al. Femtosecond laser flap creation for laser in situ keratomileusis in the setting of previous radial keratotomy. Asia Pac J Ophthalmol. 2015;4:2835.

Editors note: Dr. Rush has no financial interests related to his comments.

Contact information

Rush: Sloan.rush@paneye.com

Related articles:

Addressing the post-RK hyperopic shift by Michelle Dalton EyeWorld Contributing Writer

Technique for cortex removal with the femtosecond laser by Ellen Stodola EyeWorld Senior Staff Writer

Femtosecond laser-assisted compared to standard cataract surgery for removal of advanced cataracts Kathryn M. Hatch, MD, Tim Schultz, MD, Jonathan H. Talamo, MD, and H. Burkhard Dick, MD, PhD

Femtosecond cataract laser upgrades by Ellen Stodola EyeWorld Staff Writer

Femto lasers in cataract surgery by Michelle Dalton EyeWorld Contributing Editor

Femtosecond laser and radial keratotomy Femtosecond laser and radial keratotomy
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