Chances are you know someone—a family member, friend, or co-worker—who is enjoying the tremendous benefit of living without glasses or contacts after laser vision correction surgery. You have seen the new freedoms this surgery can bring, and want to learn more about these procedures and how you may benefit from LASIK and other laser eye procedures. LASIK is a quick, pain-free, long-lasting vision correction surgery which has been performed for over twenty years with amazing results.
What is LASIK?
LASIK, which stands for Laser-Assisted In Situ Keratomileusis, is a minimally invasive procedure intended to reduce a patient’s dependency on glasses and contacts. To achieve this goal, LASIK permanently changes the shape of the cornea. The cornea is the clear surface layer of the eye that allows light to enter and create an image on the retina, thus permitting sight. The bending and focusing of light is called refraction. If the cornea and the eye are not just right, the image on the retina can become blurred or distorted. This type of vision problem is called a refractive error.
What is a Refractive Error?
There are actually three types of refractive errors, all of which can be treated through LASIK and other laser vision correction surgeries.
Myopia or Nearsightedness
People who have myopia are said to be nearsighted, meaning that close objects can be seen clearly but the patient has trouble seeing distant objects. This refractive error occurs because the cornea focuses the light rays from distant objects in front of the retina, instead of on the retina, causing those images to be blurry or distorted.
Hyperopia or Farsightedness
With hyperopia, commonly called farsightedness, the opposite occurs. The patient is able to see distant objects clearly, but close objects become blurry or distorted. With hyperopia, the cornea focuses the light from close objects behind the retina, instead of on the retina, causing those close-up objects to appear distorted or blurry.
Astigmatism
Astigmatism can cause near and far objects to appear blurry or distorted. With astigmatism, distortions in the shape of the cornea cause incoming light rays to bend variably. This inability to focus the light onto the retina prevents images—both near and far—from becoming clear and sharp. To visualize what happens to an eye with astigmatism, imagine the health eye as a half tennis ball. Astigmatism is the result of squeezing that tennis ball half to produce an oblong, rather than round, shape.
How does LASIK correct refractive errors?
During LASIK surgery, the cornea is re-shaped—thus changing its light-focusing abilities—using a precise and controlled laser. LASIK changes the cornea so that light can focus on the retina to allow for clearer and sharper vision.
What is Laser Light?
Laser light is not like the light from the sun or a light bulb, which are made of energies that scatter in all directions. Laser light is also not like other forms of light, including x-rays, cosmic rays, and gamma rays. Unlike these, laser light is not radiation.
Laser light is called coherent light because it is made of a single color or wavelength and all of the rays travel in the same direction. The light itself is safe for medical use. However, it becomes medically effective only when mirrors and lenses create a high concentration of the laser light.
The Excimer Laser
A laser creates light much like a light bulb, but is more precise and sophisticated. The excimer laser works by passing an electric current through a tube containing a special gas (argon fluoride). The resulting reaction produces ultraviolet light energy.
Excimer lasers are precise instruments that can be directed, focused, and intensified to control the release of the machine’s laser beam. Light, in the Excimer laser system, passes through a system of mirrors that direct the light into a thin pinpointed beam. The surgeon and a highly specialized computer system control all aspects of the laser surgery, from preprogramming its beam to the actual surgical procedure itself.
The LASIK Procedure
A specialized instrument called a microkeratome gently creates an incision in the corneal surface. A small “flap” of the cornea is pulled back and a laser is used to reshape the cornea. Once the flap is repositioned, it heals rapidly and again becomes a part of the cornea.
Reshaping Vision
Instead of relying on heat, which can be less exact, the excimer laser works by focusing a very concentrated amount of light into a small area. This allows LASIK to affect only the desired treatment area, thus preventing unintended changes in surrounding tissues.
The LASIK technique harnesses this exact and focused beam of energy to reshape the tissue located directly beneath the surface of the cornea. When an eye heals from the surgery, the surface will be more normally shaped and allow light to enter properly into the retina.
With LASIK, a specialized computer is used to identify a patient’s specific eye problems. The precision of these computers is such that they can pinpoint even the slightest problem with any person’s vision. The LASIK surgery is performed with the patient lying on their backs in a comfortable and pleasant surrounding.
In using LASIK to treat myopia, as seen in this picture, the laser creates a circular area by moving very slightly. The concave area produced by the laser is directly over the visual axis, thus producing the correct angle of refraction. When the surgery is complete, the flap is placed over the area and it quickly adheres back to the corneal surface.
What are the newest Laser Eye Surgery techniques that you use?
The recent advancements in LASIK and other laser eye surgeries have improved the surgery to such precision that the already low incidence of side effects has shrunk to almost none. In addition, the new technologies such as CustomVue, WavePrint, and IntraLase systems allow for a precision unheard of before now.
The San Diego Eye Institute is pleased to offer these innovative technologies to all of our clients.
What is WavePrint?
Most Laser Eye Surgeries begin with a WavePrint scan of your eye. The WavePrint System consists of three separate VISX-branded technologies: the WavePrint Map, 3D ActiveTrak™ Eyetracker, and Variable Spot Scanning (VSS).
The WavePrint mapping system makes a finely detailed map of your eye. This "map" allows the system to locate the particular details of your eye's needed correction. The advent of the WavePrint map means that more people are able to have laser eye surgery than ever before.
VISX's 3D ActiveTrak™ system monitors your eye during the surgery itself. This allows for any natural eye movements or other variables to be effectively adjusted for by the computer during the actual procedure.
Variable Spot Scanning (VSS) allows for a larger area of the eye to be mapped out. VSS is particularly effective when the pupil needs to be involved in the laser surgery.
What is CustomVue?
Using VISX CustomVue, your doctors at the San Diego Eye Clinic can map out and identify imperfections in your eye 25 times greater than standard methods. CustomVue uses a unique system called a WaveScan that gently recreates your eye's particular shape and problems. The CustomVue system follows the eye's problem areas and a laser is directed to the spot, providing a new level of precision and accuracy
What is IntraLase?
Using the IntraLase system, your doctors are now able to perform laser eye surgery without the use of a blade. The IntraLase system creates an eye flap needed in all laser eye surgeries. Instead of relying on the old method of a handheld blade, however, the system uses the computer guided laser system. IntraLase systems of laser eye surgeries are safer, more accurate, and take less time than ever before.