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SMILE Impairs Corneal Sensation
Less Than LASIK, Study Finds
March 2014 In a recent study, a procedure called small incision lenticule extraction (SMILE) was less likely to cause reduced corneal sensation after myopia correction compared with femtosecond laser-assisted LASIK (femto-LASIK).
Researchers in China evaluated 38 eyes of 38 patients who underwent SMILE and 33 eyes of 33 patients who underwent femto-LASIK. Corneal sensitivity was tested at five areas on the surface of the eye before surgery and at one week and one, three and six months afterward.
All corneal areas tested had reduced sensation immediately after both surgeries. But the SMILE-treated eyes showed less reduction of corneal sensation than the LASIK-treated eyes during all post-surgical visits. Also, central corneal sensitivity in the LASIK-treated eyes did not return to pre-surgical levels by the six-month follow-up visit.
Since reduced corneal sensation has been associated with post-LASIK dry eye, this finding suggests the SMILE procedure could be an acceptable option for people who are not good LASIK candidates because of dry eye risk factors.
The study report was published in February in Journal of Refractive Surgery.
Do Large Pupils Cause Problems After LASIK?
November 2013 It's been suggested that people with large pupils have a greater risk of glare and halos around lights at night after LASIK surgery than people with normal-sized pupils. But is that really true?
In a study published this month in Journal of Refractive Surgery, researchers analyzed 19 studies published in peer-reviewed journals since 2002 that investigated the effect of pupil size on LASIK outcomes.
None of the reviewed studies showed a correlation between pre-operative pupil size and persistent night vision complaints after LASIK surgery when the surgical ablation zone (the area of the cornea that's reshaped by the laser) was 6.0 mm in diameter or larger and the follow-up period was at least three months.
- Have questions about dry eye? Submit them to our dry eye expert or find answers to previously submitted questions
- Learn about iLASIK advanced laser vision correction
- This useful, one-stop guide takes you through the LASIK experience before, during and after surgery
- Get relief from dry and irritated eyes with Tears Again Hydrate omega-3 gels
Studies that did find a correlation between pupil size and night vision complaints after LASIK included patients with ablations smaller than 6.0 mm or did not specify ablation size. Studies with mixed conclusions either followed patients for fewer than three months or found that patients showed an improvement in night vision over time.
The researchers concluded that in these studies, patients with large pupils did not appear to have an increased risk of night vision problems after modern LASIK surgery (which typically involves a laser ablation zone of 6.0 mm or larger), when compared with patients with smaller pupils and when patients were examined after a follow-up period of three months or longer.
New Gene Test Could Help LASIK Candidates Avoid Certain Complications
May 2013 Why are some people bad candidates for LASIK? Because they have a genetic condition called Avellino corneal dystrophy (ACD), which causes the development of white or grayish granular deposits in the cornea.
Normally these spots develop slowly, over many years, causing a gradual clouding of vision. But LASIK surgery can worsen the density of the cloudiness to the point of severely diminished vision.
A new gene test offered by Avellino Laboratory USA may be crucial in identifying people who carry the ACD gene and therefore should not receive LASIK. According to a study that was published in Ophthalmic Epidemiology, one out of every 870 people is at risk of carrying the gene.
Often people with ACD do develop the small white spots in time to be disqualified by their LASIK surgeon. But for those who don't yet have any spots in their cornea, the Avellino-GENE Detection System (AGDS) Test offers a safe way to discover if they carry the gene.
The AGDS Test involves a cheek swab that is sent to Avellino Lab USA for testing. Results are available in a couple of days. Typically the test costs around $100, though some clinics include it in the overall cost for LASIK surgery. It is not covered by insurance, but people can use their Flex Spending Accounts to pay for it.
Accelerated Corneal Crosslinking Procedure Receives CE Approval; Designed to Strengthen Eye Surface After LASIK
WALTHAM, Mass., February 2012 A procedure called Lasik Xtra, which is designed to strengthen the cornea after LASIK, has received CE approval for marketing in the European Union. It was just approved in Canada as well.
Marketed by Avedro, Inc., Lasik Xtra is a corneal crosslinking procedure that applies the company's VibeX riboflavin ophthalmic solution to the eye's surface (cornea), and then uses Avedro's KXL System to irradiate the cornea with UV-A rays. Lasik Xtra is an accelerated form of crosslinking Avedro says it takes two minutes which makes it more convenient to combine with LASIK.
Avedro said that in April it will report on studies that show the procedure has helped people who received hyperopic LASIK, which tends to regress more than myopic LASIK, to maintain the vision correction they had received from LASIK.
Although corneal crosslinking has not received FDA approval yet, Avedro's VibeX solution has received orphan drug approvals from the agency. Orphan drug status is usually conferred on treatments for rare medical conditions (in this case, keratoconus, which is a gradual thinning of the cornea).
Could Monovision LASIK Cause Strabismus?
ATLANTA, June 2011 In people with a history of strabismus, caution may be in order when considering monovision LASIK or a monovision mode of fitting contact lenses or implanting intraocular lenses.
In a recent review of the clinical records of 12 of his patients, pediatric ophthalmologist Zane F. Pollard, MD checked for a link between switching to monovision and the subsequent onset of strabismus, an eye misalignment that causes blurry vision.
Monovision is a type of vision correction in which one eye is corrected for distance vision and the other is corrected for near vision. The eyes continue to work together to focus, but one or the other eye will carry more of the load, depending on whether it's looking near or far. It is a popular option for people with presbyopia. Monovision can be induced with LASIK, contact lenses or intraocular lens implantation during cataract surgery.
Dr. Pollard and his associates wanted to know if the monovision produced new strabismus or whether the strabismus onset was related to a previously existing strabismus. The patients' near eyes were converted to distance vision, and they were asked to use reading glasses for near work. Of the 12 people, seven experienced a realignment of their eyes to normal, while five needed surgery to achieve normal alignment.
The researchers concluded that while monovision works for most people, those with a previous history of strabismus may not be suitable candidates for it, and if they do have monovision correction, the difference in refractive powers for the eyes should probably be kept small, such as 1.25 to 1.50 diopters. Dr. Pollard commented that most of his monovision surgery patients developed strabismus after two years, even though their pre-surgery monovision trial with a contact lens had suggested that they could probably tolerate monovision.
The study report appeared on the American Journal of Ophthalmology website ahead of print in June.
Kamra Corneal Inlay Shows Promise for Near Vision
IRVINE, Calif., December 2010 Ninety-seven percent of people implanted with the Kamra corneal inlay over a three-year period achieved J3 vision or better, with a mean near vision acuity of J1, according to a presentation at the American Academy of Ophthalmology's annual meeting in late October.
J3 and J1 are measurements on the Jaeger near point eye chart, used to determine how well you can see printed letters when reading up close. The type scale ranges from J1 (smallest) to J20.
Also, 91 percent achieved intermediate visual acuity of 20/32, so they were able to not only read the newspaper, but also see computer screens and road signs, all without glasses or contact lenses.
The procedure involves making a corneal flap. The Kamra inlay is donut-shaped and is placed in the center of the cornea of the non-dominant eye; then the flap is placed over it. The inlay uses "pinhole" optics to block peripheral light but allow central light to come into the eye, which improves near vision. The Kamra inlay is removable if necessary.
AcuFocus launched the Kamra intracorneal inlay in Europe and Asia in October. It is still in testing in the United States.
Is It Safe To Have LASIK After Cataract Surgery
To Refine Your Vision?
ALICANTE, Spain, December 2010 A retrospective study of 100 eyes showed that after cataract surgery with either monofocal or multifocal intraocular lens (IOL) implantation, LASIK was generally safe and effective in refining vision even further.
Also, hyperopic LASIK for farsightedness provided a less predictable outcome in the multifocal IOL eyes.
The study appeared in the Journal of Refractive Surgery in August.
Renamed the Vue+, PresbyLens May Undergo
Expanded Clinical Testing Soon
ReVision Optics, which is developing the inlay, has renamed it Vue+ and filed with the FDA to expand the trial to three years and 400 presbyopic subjects.
The Vue+ is a small, contact lens-type device that is inserted under the surface of the eye to reshape it, for improved near vision.
UPDATE: As of September 2012, the product is now called Raindrop Near Vision Inlay.
Femtosecond-Only Laser Vision Correction Introduced
DUBLIN, Calif., May 2010 Carl Zeiss Meditec has released its new ReLEx vision correction method outside the United States. ReLEx uses only the VisuMax Femtosecond laser, as opposed to other LASIK methods that use a combination of a femtosecond laser or a microkeratome (blade) to create the flap and an excimer laser to correct the vision problem.
In the ReLEx version of LASIK, a flap is cut and a piece of tissue called a lenticule is created under the eye's surface. The tissue is lifted out, and the flap is replaced on the eye.
In a release, Carl Zeiss Meditec CEO Ludwin Monz commented that the system would deliver "unprecedented workflow benefits" to refractive surgery practices.
The VisuMax Femtosecond laser can be used for vision correction procedures other than LASIK, such as the FLEx (femtosecond lamellar extraction) method and the SMILE (small incision lamellar extraction) method. ReLEx allows for small flap sizes, too. As of April 10, ReLEx procedures had been performed on more than 1,000 eyes outside the U.S.
PresbyLens Clinical Trials Begin
ReVision Optics is developing the procedure and conducting the trials, which will treat 30 eyes in Greenwood Village, Colo., and Houston during the first study phase.
The PresbyLens is very thin, is made of a biocompatible material similar to that of a contact lens and is inserted in the cornea, reshaping just the center of it in order to improve near vision. The procedure takes about 20 minutes. The PresbyLens is already approved for sale in Europe.
UPDATE: As of September 2012, the product is now called Raindrop Near Vision Inlay.
Microwave Energy Used in Vision Correction Procedure
WALTHAM, Mass., April 2010 A new type of vision correction surgery called Keraflex applies microwave energy in a ring-shaped pattern to the periphery of the cornea to flatten it and thereby reduce or eliminate myopia.
The energy causes collagen in the cornea to shrink, which makes it flatter, and in that respect is similar to CK, which uses radiofrequency energy to achieve the same type of collagen shrinkage.
During the microwave procedure, the surgeon controls the temperature of the cornea with a coolant, then applies the microwave energy to the cooled area. The method is designed to avoid damage to the outer layer of the cornea.
The procedure may appeal to those who have less severe myopia than those who normally choose LASIK and who may have fears about undergoing LASIK. The microwave energy procedure involves no cutting of eye tissue and does not permanently alter the cornea.
According to Avedro, Inc., the company that is developing the Keraflex procedure and the Vedera KXS machine that delivers the microwave energy, the procedure is in clinical testing in Europe and is planned for testing in the United States this year.
Please click here for more LASIK and other refractive surgery news from 2009.
[Page updated March 3, 2014]
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