jueves, 1 de marzo de 2012
Artículo acerca de FLEX-Relex Zeiss "refractiva intraestromal"
FLEx (short for "femtosecond lenticule extraction" or "femtosecond lamellar extraction") is a new all-laser refractive surgery procedure designed for the correction of myopia.
The FLEx procedure takes place entirely within the cornea and is performed exclusively with afemtosecond laser system.
Femtosecond lasers are capable of making extremely smooth and precise "cuts" within the cornea at computer-controlled depths without affecting the surface of the eye. This unique capability is what makes the new single-laser FLEx procedure possible and may provide advantages over current excimer lasers used for LASIK eye surgery.
The FLEx Procedure
The all-laser FLEx procedure consists of four steps:
The refractive surgeon uses the laser to cut a small lens-shaped segment of tissue (lenticule) within the center of the cornea.
The surgeon then makes a flap in the anterior cornea with the laser — similar to the flap created in all-laser LASIK.
The flap is lifted and the lenticule is removed and discarded.
The flap is repositioned, as in LASIK.
The removal of the lenticule reduces the curvature of the cornea, thereby reducing myopia.
A variation of FLEx is another investigational procedure called small-incision lenticule extraction (SMILE).
For these reasons, it is best to try monovision with contacts before committing to more permanent monovision with LASIK.
In the SMILE procedure, the corneal flap is eliminated. Instead, a small incision is made in the mid-periphery of the cornea with the laser, and the lenticule is removed through this self-sealing incision.
FLEx may induce fewer higher-order aberrations than LASIK or PRK, for sharper vision overall, and especially at night.
FLEx may be more accurate than LASIK when correcting relatively high amounts of myopia.
The SMILE procedure has additional potential advantages. Because no corneal flap is created, SMILE may pose less risk for post-surgical dry eye and ectasia than FLEx or LASIK.
Also, since SMILE is a no-flap procedure, there is no risk of flap displacement from trauma to the eye after surgery.
FLEx With Zeiss ReLEx
In April 2010, Carl Zeiss Meditec (Dublin, Calif.) announced the introduction of its new ReLEx application that allows eye surgeons to perform FLEx and other all-laser procedures using the company's latest VisuMax femtosecond laser.
FLEx and other procedures have been performed with VisuMax lasers on more than 1,000 eyes at a variety of locations outside the United States, according to the company's press release.
In a recent study conducted in Alexandria, Egypt, FLEx performed with the ReLEx VisuMax femtosecond laser system compared favorably with LASIK in terms of effectiveness, stability and safety, according to Zeiss.
In the study, 102 eyes with myopia and myopic astigmatism were treated with the Zeiss FLEx procedure. Prior to surgery, the mean spherical equivalent amount of myopia in all eyes was –5.07 diopters (D).
Results of the study included:
84 percent of eyes achieved uncorrected distance visual acuity (UDVA) of 20/25 or better the day after surgery.
85 percent showed UDVA of 20/20 or better one month after surgery.
At one month after surgery, mean spherical equivalent refractive error was –0.17 D of myopia.
At 3 months after surgery, 95 percent of eyes were within 1.00 D of the intended correction and 76 percent were within 0.50 D.
The Future of Refractive Surgery?
The promising early results of the FLEx procedure suggest it may someday become a popular alternative to LASIK for the correction of nearsightedness.
Currently, FLEx and SMILE all-laser vision correction procedures are not FDA-approved for use in the United States.
Carl Zeiss Meditec has received a CE Mark for use of its VisuMax femtosecond laser system for FLEx in Europe. The company says it is continuing to perform clinical research on the ReLEx system and expects its SMILE procedure will be available for use outside the United States in 2011.
Refractive surgery procedures and techniques continue to evolve at a rapid pace. If you are interested in FLEx or SMILE, schedule a consultation with an experienced refractive surgeon near you for the latest information about the approval status and availability of these new all-laser vision correction procedures.
Cost for FLEx and SMILE
The cost for FLEx and SMILE all-laser surgery to be provided by surgeons in the US has not yet been established, but it is expected to be similar to other laser eye surgery cost.