Types of Laser Surgery

The Dawning of A New Era

Since the late 1970's incisional refractive surgery has treated vision abnormalities in patients all over the world allowing them to experience a new kind of freedom. It's the kind of freedom that allows people to make lifestyle choices that were not options to them before, because they were totally dependent on glasses or contact lenses. 1988 marked the dawning of a new era in refractive surgery with the advent of the Excimer laser. For as many as 25% of the population, the Excimer laser could represent the first step towards less dependence on corrective lenses.

The Excimer laser is a computer controlled ultraviolet beam of light that sculpts the cornea into the shape it requires to bring light to focus more directly on the retina, thereby reducing or eliminating a variety of refractive errors. The Excimer laser was invented in the early 1980's and has undergone numerous clinical trials since that time to refine its use and determine its safety and effectiveness. The Excimer laser is now routinely used around the world to treat nearsightedness, farsightedness and astigmatism.

What makes the Eximer such a revolutionary tool?

Each pulse of the laser disrupts the molecular bonds between the corneal cells with accuracy up to 0.25 microns (or 0.00004 of an inch) which makes it extremely accurate. The more tissue removed, the more the refractive power of the cornea is altered. Often, only 50 microns of tissue, i.e., about the thickness of a human hair, are removed to achieve the proper amount of correction.

The Excimer laser produces a "cool" or non-thermal light beam as most of its heat is dissipated into the air. This makes it ideal for corneal surgery because it eliminates the possibility of thermal damage to surrounding tissue. Its accuracy, combined with its non-thermal characteristics, provide refrac­tive surgeons with a tool that can deliver more consistent  and  predictable  results  than incisional procedures such as Radial Keratotomy.

Eximer Laser Procedures

PRK
PRK or Photo-Refractive Keratectomy treats refractive errors by removing tissue from the surface of the cornea. First, your eye is numbed using a topical, or eye drop anesthesia. Then, the surgeon removes the epithelium, a thin layer of protective skin that covers the cornea. This may be done with either a blade, a brush or even the Excimer laser. During the actual procedure, the patient stares at a fixation light. In less than a minute, the laser removes the proper amount of tissue while it reshapes the surface of the cornea.  After PRK the eye is patched until the  following morning. Because the epithelium was removed, patients may experience blurry vision for three to five days and a low to moderate amount of discomfort until the epithelium heals and covers  the treated area.  Eye drops, narcotics and possibly a contact lens are effective in reducing this postoperative discomfort. Final visual results may be fully realized anywhere from several days to a few months or more as the surface heals in accordance to each individual's healing tendencies. PRK is most often used to treat individuals whose corneal thickness is too thin for LASIK.

LASIK
LASIK or Laser in-Situ Keratomileusis treats nearsightedness, farsightedness and astigmatism by removing corneal tissue beneath the surface of the cornea. This procedure combines the accuracy of the Excimer laser with the benefits of lamellar Keratoplasty (LK). LK has been performed since 1949 to correct higher levels of nearsightedness and moderate  amounts  of farsightedness. More recently LK was refined by technological advancements of an instrument called a microkeratome that allows the surgeon to fold back a thin layer of cornea. To treat nearsightedness, a second pass of the microkeratome was required to remove corneal tissue from the inner cornea. However, the quality and accuracy of this second pass could not always be achieved.  With LASIK, instead of making a second pass with the microkeratome (as in LK), the Excimer laser removes the proper amount of corneal tissue with much greater accuracy.  How much tissue removed is controlled by the number of pulses and the size and shape of the laser beam. The corneal tissue is then folded back into its original position where it bonds after only a few minutes of drying. No stitches or eye patches are required after the procedure. Since only the edge around the corneal flap needs to heal, visual recovery is rapid and  patients  report  little  or  no postoperative pain. Additionally, there may be less risk of scarring or developing corneal haze. There is also less need for postoperative medications with LASIK than PRK. LASIK treats low to very high levels of refractive errors. However, because of the microkeratome, LASIK carries additional surgical risks.

Wave Front Technology

This new form of LASIK goes by the VISX trade name of CustomVue (individualized laser vision correction). 
A WaveScan is performed first that identifies and measures imperfections in an individual's vision 25 times more precisely than standard methods used for glasses and contact lenses. The WaveScan information is then transferred to the CustomVue laser.  This enables a doctor to measure and correct unique imperfections in each individual's vision that could never be measured before with standard methods used for glasses and contact lenses.  With the CustomVue procedure, nearsighted and astigmatic individuals have the potential to achieve a new level of vision that we call Personal Best Vision. 

Crystalens - the accommodating (focusing) intraocular lens is not just for cataract patient.

If you are over forty it will not be long before you will find it more and more difficult to change your vision from far to near.  This is because your natural crystalline lens is becoming larger and harder.  This prevents your lens from focusing as it once did and is why you may need glasses or bifocals to read this right now.  This inability to focus, or accommodate, is called presbyopia and its earliest symptom is a difficulty seeing things that are close up.  This same lens will eventually turn cloudy as it becomes a cataract. For the past 30 years, eye surgeons, have treated cataracts by replacing them with artificial lenses, or IOL's.  While million of Americans successfully undergo this proven surgery each year, in most cases, patients still require glasses for reading after cataract surgery.  This is because all previously available IOL's were stationary and did not adjust to focus, or accommodate. 

CRYSTALENS  works like the eye's natural lens to allow most patients to see images that are near, intermediate, and distant without glasses. This procedure can alleviate the need for distance and near glasses and because it is a cataract procedure the patient would also never get cataracts.

For more information contact your eye doctor or go to http://www.crystalens.com.

Comparision of PRK & LASIK

This information is presented to demonstrate the relative differences between PRK and LASIK. Additional factors such as surgeon experience and preference, type of lascr, age of patient, amount of correction and clinical protocols may effect these comparisons.

	PRK	LASIK
Range of Correction	Low to moderate	Low to severe
Wound Depth	Superficial	20% deep
Intraoperative Pain	None	None
Postoperative Pain	Low to Moderate 24 - 48 hrs.	Minimal 12 hours
Postoperative Medications	3 months possibly more	1 - 2 weeks
Functional Vision Recover	3 to 5 days	24 hours
Visual Results Fully Recognized	3 wks to several months	1 day
Return to Work	3 to 5 days	1 day
Risk of Complications	Low (less surgeon dependent)	Low (more surgeon dependent
Risk of Scarring in Central Cornea	1 - 2%	Less than 1%

     
Are You A Candidate For Laser Vision Correction?

In general, the ideal patient has a healthy cornea, and must not have had a significant increase in their prescription in the last year. People with certain medical conditions or pregnant women may not be good candidates.

Realistic Expectations
The decision to have Laser Vision Correction is an important one that ultimately, only you can make. It is important that you have realistic expectations and that your decision is based on facts, not hopes or misconceptions. The goal of any refractive surgical procedure is to reduce your dependence on corrective lenses. Laser Vision Correction does not always create 20/20 or even 20/40 vision. It cannot correct a condition known as presbyopia, or aging of the eye, that normally occurs around age 40 and may require the use of reading glasses. In fact, people over 40 who have their nearsightedness reduced with surgery may find they need reading glasses after the procedure. Your doctor will provide you with additional information and options.

The First Step
Finding out more about the health of your eye and your refractive error is your  first  step  toward visual independence. This is accomplished by calling your eye doctor and scheduling a personal consultation. Should your refractive error fall within the range of correction for Laser Vision Correction, more comprehensive tests will be necessary.  This information will help you and your doctor determine which procedure is in your best interest.

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