Bladeless LASIK: Creating a
LASIK Flap With Precision
Instead, bladeless LASIK uses two different kinds of lasers:
- Femtosecond laser. This laser directs laser energy precisely to create a thin, hinged flap, which then is lifted temporarily from the eye's surface or cornea.
- Excimer laser. Energy from this type of laser is applied to the newly exposed eye surface, where tissue is removed in a precise pattern to alter the cornea's shape.
In all LASIK procedures, including bladeless forms, the flap then is put back in place to serve as a natural "bandage" for better comfort and healing.
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Types of Bladeless LASIK, Beginning With IntraLase
The first femtosecond laser approved for bladeless LASIK in the United States was the IntraLase laser, which gained FDA approval in 2001. IntraLase Inc. later introduced several new models of this laser with advanced features.
Advanced Medical Optics (now Abbott Medical Optics) in 2007 acquired IntraLase, which was incorporated into the company's CustomVue excimer laser platform. This new, integrated system is marketed now as iLASIK.
The IntraLase femtosecond laser also can be used in combination with any other approved excimer laser for bladeless LASIK procedures.
Other bladeless laser systems also are entering worldwide and U.S. markets. These include:
- zLASIK. Ziemer Ophthalmic Systems received FDA approval in March 2008 for its portable femtosecond laser, known as the Ziemer Femto LDV. This femtosecond laser attaches to a movable arm and can be combined with any approved excimer laser system to create a flap for bladeless LASIK.
- Femtec. This femtosecond laser from 20/10 Perfect Vision received FDA clearance in 2004 and also can be combined with an approved excimer laser system for bladeless LASIK procedures.
- VisuMax. FDA-approved in 2007, the VisuMax femtosecond laser system typically is combined for bladeless LASIK with the Carl Zeiss Meditec Mel 80 excimer laser outside the United States. The Mel 80 received FDA approval in 2006. Company officials in late 2008 announced positive results at three U.S. centers where the combined laser systems have been used for bladeless LASIK.
Considering Complications: Blade Versus Bladeless
While LASIK complications are relatively rare, sometimes they are associated with the oscillating blade used with traditional microkeratomes. Metal blades might create uneven flap edges, resulting in abnormal corneal surfaces and vision defects such as irregular astigmatism.
Metal blades also have been associated with incomplete or improperly formed "buttonhole" flaps that can cause vision-threatening scars. Many eye surgeons report these types of complications are far less likely with laser-created flaps.
As an alternative to microkeratomes, bladeless LASIK creates flaps through infrared laser energy that inserts a precise pattern of tiny, overlapping spaces just below the corneal surface.
The femtosecond laser used in bladeless LASIK procedures operates at extremely high speeds (pulses of one quadrillionth of a second), allowing tissue to be targeted and divided at a molecular level without heat or impact to surrounding tissue.
Some study results show that bladeless LASIK results in significantly fewer overall LASIK complications. But eye surgeons have reported postoperative complications that appear related to laser-created flaps:
- One complication is a higher rate of light sensitivity such as photophobia. (Light sensitivity can occur with any LASIK procedure, bladeless or not.) The temporary effect resolves within a few weeks of steroid treatment (eye drops) and doesn't threaten vision.
- A second complication was reported in one study in which 19 percent of patients reported seeing a "rainbow effect" around light sources.* This effect is considered minimal and has declined with recent adjustments to the way laser-created flaps are made.
- Results of a retrospective study published in the November 2010 issue of the Journal of Cataract and Refractive Surgery found that bladeless LASIK was associated with more instances of a complication known as DLK (diffuse lamellar keratitis), causing inflammation under the flap. But microkeratomes were more likely to create epithelial defects on the eye's surface.
The tradeoff for extra safety with the use of bladeless LASIK is higher cost. Expect additional LASIK procedure costs of about $300 per eye, according to an AllAboutVision.com special report. Other eye surgeons bundle the cost of bladeless LASIK into their overall fee.
Usually patients are given the choice of having their LASIK flaps cut with a blade or created with the more expensive laser technology. But the blade vs. bladeless debate continues among eye surgeons, many of whom still prefer to use a microkeratome particularly with recent refinements in microkeratome technology that enable greater precision and creation of ultra-thin flaps.
Still, the popularity of bladeless LASIK is growing among surgeons. In 2008, a survey conducted by the American Society of Cataract and Refractive Surgery (ASCRS) found that 34 percent of LASIK surgeons preferred bladeless LASIK, and a separate survey by the International Society of Refractive Surgery of the American Academy of Ophthalmology found that 40 percent of surgeons preferred using a femtosecond laser to a bladed microkeratome for LASIK flaps.**
How Bladeless LASIK Works
The LASIK surgeon uses computer software to guide the femtosecond laser beam, which applies a series of tiny bubbles within the central layer of the cornea. The resulting corneal flap is created at a precise depth and diameter pre-determined by the surgeon.
As occurs with a mechanical microkeratome, a small section of tissue at one edge of the flap is left uncut, forming a hinge that allows the surgeon to fold back the flapfold back the flap so the cornea can be accessed and reshaped for vision correction.
How Bladeless LASIK Compares With Blade Flap LASIK
With bladeless LASIK, people with thin corneas who once were deemed unsuitable for LASIK may now be candidates. Most people have corneas that are between 500 and 600 microns thick. To maintain corneal stability and avoid serious LASIK complications such as ectasia, surgeons want to leave as much corneal thickness under the flap as possible. So, generally speaking, the thinner the corneal flap the better, because this leaves a greater amount of corneal tissue under the flap for treatment.
Most microkeratomes previously cut flaps that generally ranged in thickness from 140 to 180 microns. Femtosecond lasers, on the other hand, can create flaps as thin as 100 microns. So at one time, bladeless LASIK had a distinct advantage over microkeratomes in terms of the ability to make thinner flaps. This meant that people with thinner-than-average corneas who may not have been good candidates for conventional LASIK could safely have all-laser LASIK performed on their eyes.
But newer types of microkeratomes now make flaps that are as thin as those created with femtosecond lasers, according to AllAboutVision.com Advisory Board member and refractive surgeon Brian S. Boxer Wachler, MD. Flaps made with either technology now consistently can be made as thin as 100 microns.
Refractive surgeons also say that PRK is and was an option for qualified candidates with thin corneas, because no flap is created in this procedure. Instead, the eye's surface is reshaped directly with the excimer laser.
In some cases bladeless LASIK may cause fewer LASIK complications. Femtosecond lasers create corneal flaps with more defined, angled edges, unlike the thinner, microkeratome-cut "knife-edge" flaps that might tear more easily.
Laser-made flaps also can be created with more accuracy, says Vance Thompson, MD, a Sioux Falls, S.D., refractive surgeon with experience using femtosecond lasers since early 2002. Dr. Thompson also is an AllAboutVision.com Advisory Board member.
"Parameters such as side cut angle and hinge size are adjustable with the laser flap method but not with the blade flap method," Dr. Thompson said. "The laser flap method allows the surgeon to create a more customized flap for the patient."
Dr. Thompson said corneas are oval, not perfectly round. He said blade-created flaps are round, whereas a laser can create an oval flap in whatever shape is needed to better match the cornea.
"Also, with the blade flap maker, we cannot vary hinge location," Dr. Thompson said. "But with the laser flap maker, we can place the hinge wherever we want for 360 degrees."
Dr. Thompson said an inverted side cut also can be made so the flap angles in as it goes deeper, rather than angling out as occurs with a blade flap. He said cornea flaps are less weakened when created by a laser.
This difference in flap structure and architecture also may improve flap adherence and reduce the chance of surface cells of the cornea growing underneath and pushing up the flap (epithelial ingrowth) to create an irregular corneal surface with accompanying vision defects.
Dr. Thompson said that some microkeratome flaps, instead of adhering to the cornea, still can be lifted easily many years after surgery.
However, Dr. Boxer Wachler said that new technology has resolved many previous problems associated with flaps produced with microkeratomes. He supports conventional LASIK with microkeratomes in uncomplicated LASIK cases for the procedure's cost savings and convenience.
Certain flap complications may be avoided. Complications such as "buttonholed" or partially formed flaps associated with microkeratomes might be avoided with the femtosecond laser. But Dr. Boxer Wachler says buttonholes have been reported with femtosecond lasers as well.
You may have less chance of an eye infection or contamination during creation of the bladeless flap. This is because the tear film and other debris are not "dragged in" under the flap, as can occur with a blade flap maker.
You may develop temporary eye redness. All-laser LASIK now uses a low vacuum suction ring to hold the eye, compared with a higher vacuum used for microkeratomes. The time needed for newest versions of femtosecond lasers used to create flaps is about 10 seconds, although older laser flap-making technology can take up to a minute.
This amount of time for the suction ring to remain on the eye may slightly increase chances of some superficial bleeding on the white part of the eye (subconjunctival hemorrhage) for all types of LASIK. This temporary eye bleeding is not vision-threatening. It is strictly a cosmetic issue and resolves on its own in about three weeks, if the redness occurs at all.
People who have had previous corneal surgery often are candidates for bladeless LASIK. Dr. Thompson reports that he now uses laser-created flaps for most people who have undergone previous corneal surgeries such as radial keratotomy (RK), a now obsolete vision correction surgery that involved making cuts into the cornea.
But Dr. Boxer Wachler points out an increased risk of epithelial ingrowth for any form of LASIK performed over RK. He said PRK is the preferred procedure in these cases, because of risks involved with creating a flap of any kind.
More surgeon experience with computer-guided laser creation of LASIK flaps and further analysis of their results should confirm whether bladeless LASIK is a significant advance.
Other Uses for Bladeless LASIK
Less traditional approaches using all-laser LASIK are under investigation. In August 2008, the American Journal of Ophthalmology reported that bladeless LASIK helped sharpen vision following refractive lens exchange (RLE).
In the study, RLE was performed using multifocal intraocular lenses that provide greater ability to see at all distances following a procedure. Bladeless LASIK then was used to refine visual outcomes.
Investigators said more study is needed. Proper testing also is needed to help devise an appropriate treatment plan and select the right candidates for RLE combined with bladeless LASIK.
What Happens After the Bladeless LASIK Procedure?
Recovery is similar to that of traditional LASIK. Following surgery, some people (as with traditional LASIK) have reported feeling eye irritation for up to two days.
Study results have shown that a bladeless procedure may produce a lower incidence of dry eye after LASIK. Fewer enhancement ("touch-up") procedures seem to be required when bladeless LASIK is performed. But Dr. Boxer Wachler says that thin flap microkeratome LASIK also now has a lower incidence of dry eyes.
If you have lingering questions about whether bladeless LASIK is right for you, be sure to discuss them in-depth with your eye surgeon.
**Femtosecond laser use in U.S. increasing, but some still prefer microkeratomes. Ocular Surgery News. May 2009.
[Page updated May 2013]
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