Archive for the ‘wavefront’ Category

Does Pupil Size Matter in LASIK?

Saturday, November 3rd, 2012

 

Two potential side-effects of LASIK eye surgery are “starbursts” and “halos”.

The short answer is yes. The more precise answer is “It doesn’t have to matter.” The pupil acts as the apperature in a camera constricting in bright sunlight to protect and dilating under dim illumination situations to allow maximum light for visual function at night. Many pupils can be as small as 2 mm in bright light and enlarge to as much as 7 mm or more in the dark. The side-effect of halos and starbursting around lights at night is well known in LASIK and various other eye surgeries and is easy to understand if you consider that LASIK, as originally performed, treated only the central 5.5 to 6 mm of the cornea. The admonition against LASIK in patients with large pupils was easy to understand and was logical when all LASIK was conventional, as performed over 10 years ago. Today, however, we have the ability to treat with much larger treatment zones and with a technology known as “custom” or wavefront-guided LASIK. Several large studies found that pupil size had no relation to night vision problems when wavefront technology was utilized to perform the LASIK procedure. Data from studies utilizing a VISX laser with wavefront guided LASIK treatments found that night vision problems were reduced 20-fold compared to conventional LASIK. Patient satisfaction with their night-vision actually had a tendency to increase compared to night-vision satisfaction with glasses or contacts when wavefront-guided LASIK was performed.

So, as long as your LASIK surgeon is using the latest technology, you can ignore the out-dated advice warning against LASIK in large pupils. Of course, before undergoing LASIK or any other type of surgery, you should discuss all risks and concerns and be sure you understand and are comfortable with these before proceeding. Improvements in LASIK technology continue to improve success rates and reduce the risk of side-effects. To maximize your chances for success, don’t settle for just LASIK: insist on wavefront-guided LASIK.

Tags: , , , ,
Posted in lasik, LASIK Complications, wavefront | No Comments »

LASIK for Pilots (and Astronauts)

Sunday, September 23rd, 2012

Thanks to advanced LASIK, many more now are pilot candidates.

Used to be if you weren’t blessed with naturally good vision, you were disqualified from becoming an airforce pilot or astronaut. Thanks to LASIK eye surgery and some of the newer innovations in vision correction surgery, all of that has changed. After years of study, the Air Force has decided to change their long-standing policy which disqualified applicants who have had LASIK surgery from flight training and navigator training. Prior to the change, officers who had had the surgery, prior to flight school could not become Air Force aviators. Under the old policy, a select-few pilots and navigators who had already graduated from flight training could apply to have the surgery and become part of an on-going study group. The change also removes the altitude and high-performance aircraft restrictions for people who have had LASIK.

The results of the study are in, and the Air Force found that there was little to no effect on LASIK-treated eyes when subjected to high G-forces of combat fighter aircraft, the wind blast experienced during aircraft ejection, or exposure to high altitude.

Due to stresses placed on the eyes during flight combined with the active lifestyle of military members, the recommended refractive surgeries are Wave Front Guided Photorefractive Keratectomy, or WFG-PRK, and Wave Front Guided Laser In-Situ Keratomileusis, know as WFG-LASIK, using the femtosecond laser (IntraLase). The eyes are more trauma resistant after surgery using one of these methods compared to other forms of refractive surgeries.

Shortly after the Airforce and Navy removed the LASIK restriction for fighter pilots, NASA followed suit in allowing LASIK for astronauts. Prior to the removal of these restrictions, poor vision was one of the most common causes for disqualification of aviator candidates. Now thanks to LASIK eye surgery, the future is looking a lot brighter for those who want to reach for the stars. Of course, as with any surgery, there are no guarantees and individuals interested in an aviation career must still meet the vision standards dictated by the armed forces.

Tags: , , , , ,
Posted in Intralase, lasik, wavefront | No Comments »

What is the Best LASIK?

Monday, September 17th, 2012

Many consumers are confused by the various claims made by advertisers about LASIK. Many LASIK providers claim to have the “latest technology” or “most advanced technology”. Some consumers assume that LASIK provided anywhere is the same. Is there a difference between different types of LASIK and is so is there any “best LASIK”?

LASIK is a general term referring to a vision correction procedure consisting of two steps: the creation of a flap and reshaping of the cornea underneath the flap. Both steps of the LASIK procedure have had refinements over the years and several different medical companies have offered instruments used in the procedure. LASIK surgeons are free to use instruments from any company they choose to perform vision correction. And just like the making any purchase decision: a car, a computer, a dishwasher etc., a variety of factors, including cost, quality and reliability can come into play in deciding what instruments a LASIK surgeon decides to use. Not surprisingly, the better quality instruments cost more to purchase and use than lower quality instruments.

So what are the various choices in LASIK technology? Basically it comes down to customization and precision. The more “customizable” and precise the technology, the safer and more reliable the oucome.

The iFS model of IntraLase laser is the most sophisticated laser to make the LASIK flap.

For the flapmaking step of the LASIK procedure, at present, the most sophisticated and safest method is using AMO’s iFS laser. It has the lowest complication rate and offers the most secure flaps.

AMO’s CustomVue technology uses wavefront mapping to yield the highest quality vision with fewest side-effects.

For the vision correction part of the LASIK procedure, the undisputed best method to reshape the cornea is using AMO’s CustomVue technology. This method gives the highest percentage of 20/20 results and the lowest incidence of night time side effects such as starbursting around headlights.

So while selecting the “best” car or refrigerator may not be obvious, the clear choice for the best LASIK procedure is the OmniLase technique: the combination of a customized LASIK flap with the iFS laser combined with AMO’s CustomVue technology.

 

Tags: , , , ,
Posted in Intralase, lasik, LASIK Complications, lasik cost, wavefront | 1 Comment »

Wavefront Technology and LASIK

Sunday, September 2nd, 2012

Optical aberrations can effect the quality of vision after LASIK

 
Early in the history of LASIK eye surgery, a small sub-group of patients complained about the quality of their vision.  Some actually had 20/20 levels of vision but described issues of “vision not being crisp” or “poor contrast”.  Some complained of disturbed night vision: star-bursting or halos around lights.  Out of a desire to solve these patients complaints, the science of wave-front guided LASIK science was born.

A standard LASIK procedure is based solely on a patient’s eyeglass prescription. A wavefront-guided LASIK is a treatment based on all of the eye’s measured optical aberrations. These aberrations are measured with a sophisticated device called a wavefront-analyzer, which essentially takes a “fingerprint” of the eye. This unique “fingerprint” is then recorded and used to correct vision with a sophisticated, computer-controlled laser.

But the use of a wavefront-analyzer to perform LASIK added time and cost to the procedure.  A “shortcut” was developed to reduce time and cost: the wavefront-optimized LASIK procedure.  An “optimized” LASIK procedure was designed to be aberration-neutral, neither creating nor reducing aberrations. The treatment is still based on the refractive prescription in glasses. It does not measure and cannot correct optical aberrations in the eye.

A wavefront-optimized procedure is better than a standard LASIK procedure because it tends to reduce the incidence and severity of new aberrations. A wavefront-guide procedure is even better than a wavefront-optimized procedure because it actually measures and treats pre-existing higher-order aberrations Wavefront-guided LASIK procedures, just like optimized, can minimize induction of spherical aberrations. But it can also measure and treat other higher-order aberrations.

There is no disputing that wavefront-guided LASIK uses much higher technology and is more expensive than standard or wavefront-optimized LASIK. But the real advantage of a wavefront-guided LASIK is more than just higher technology. Studies have demonstrated that a wavefront-guided LASIK results in better outcomes and better visual quality — especially when it comes to vision at night or in a dark environment, or when there is a high visual demand.

A wavefront-optimized LASIK procedure tends to reduce the incidence of visual side-effects as compared to standard LASIK but for the ultimate in outcomes, choose a wavefront-guided LASIK procedure.

 

New aberrations created from standard LASIK can cause “starbursting” at night. Wavefront-guided LASIK can minimize or eliminate starbursting.

 

 

Tags: , ,
Posted in lasik, LASIK Complications, lasik cost, wavefront | No Comments »

LASIK: A Good Procedure Gets Better

Tuesday, August 2nd, 2011

LASIK has it’s roots in a procedure first performed over 50 years ago.  A Columbian ophthalmologist described performing a procedure termed “keratomileusis” or corneal reshaping procedure to correct extreme amounts of nearsightedness using a bladed microkeratome and a lathe.  Others began performing the procedure and refined it with better instrumentation and techniques to yield better results and improved safety.  Eventually the excimer laser was introduced to replace the lathe in the reshaping part of the procedure and the term LASIK (laser assisted in-situ keratomilieusis) was applied to the “new” procedure. With the improved precision brought about by the excimer laser came wider acceptance of the procedure and eventual FDA approval.
  As with most things in medicine, continued improvements and refinements have taken place.  Two of the bigger refinements were the addition of wavefront technology to improve the final optics of the reshaped cornea and the introduction of a second laser: the femtosecond laser (IntraLase).  Today’s LASIK procedure is far advanced from earlier generation procedures.  Outcomes are improved with higher levels of 20/20 vision, lower levels of side-effects such as night vision difficulties and a safety profile that surpasses that of contact lens wear. 
   If you are contemplating LASIK or any other vision correction procedure, you should not presume that you will automatically benefit from all the refinements that have taken place.  Upgrading and replacing equipment is an expensive proposition and some doctors and LASIK centers may not be willing to invest in new technology.  That puts the responsibility on you, the patient, to investigate and determine if you are comfortable with the technology to be used in your procedure.  If you have made the decision that improvements in the LASIK procedure have now made it a viable option for you, it is up to you to determine whether you, in fact, will be receiving this better procedure.

Tags: , ,
Posted in Intralase, lasik, wavefront | No Comments »

Night Vision and LASIK

Sunday, March 13th, 2011
CustomVue technology actually increases patient night vision satisfaction.

CustomVue technology actually increases patient night vision satisfaction.

Night glare and starbursts are a potential side-effect of any eye surgery.
Night glare and starbursts are a potential side-effect of any eye surgery.

Many people who have never had eye surgery, if they are careful observers, can notice some starburst, halo, glare, or shadows in their vision under low light conditions, especially if they need to wear glasses or contact lenses. It is common to notice one or more of these after LASIK eye surgery, especially during the early postoperative period. These side effects generally diminish with time but some patients will notice one or more of these even with excellent correction, sometimes for a long time or even indefinitely. Of those patients who do notice these side effects, most will find them annoying and it is possible that some patients may feel they cause mild to serious visual impediments.
The LASIK procedure creates a change in curvature in the central part of the cornea. If changing the corneal curvature also results in distortion of the cornea then aberrations in vision quality may result. These aberrations in vision may be most noticeable at night, when the pupil opens wide. This can result in seeing a halo type effect or perhaps just a decreased contrast or sharpness of vision. Regardless of how it is described, there are some patients who feel that their night or reduced light vision is poor even when their uncorrected vision is good or excellent in normal lighting. This may be a significant issue for some patient for night driving, playing tennis or baseball at night or other similar activities, even before refractive surgery is performed. A technology developed by AMO/VISX termed CustomVue and utilized in the iLASIK procedure was developed in an effort to improve night vision. The CustomVue technique makes use of a wavefront analyzer to measure and correct visual aberrations. Clinical studies show that more patients are actually satisfied with their night vision after LASIK when this technique is used. The wavefont guided CustomVue technique should not be confused with the wavefront optimized technique utilized by the Wavelight/Allegretto laser. Only the CustomVue technology associated with iLASIK results in better night vision.

Tags: , , , , , , , ,
Posted in lasik, Uncategorized, wavefront | 1 Comment »