About Lasik Corrective Surgery
What is LASIK?Does LASIK Work?
Who Is A Candidate?
What is it like to have LASIK?
How can I find out if I am a candidate?
Anatomy of the eye
Refractive Errors
What is Lasik?
Lasik is an acronym for the procedure known as Laser Assisted In-Situ Keratomileusis. It is a two step procedure which essentially combines the long ago described technique called ALK (automated lamellar kertomileusis) with PRK. In ALK a special instrument was used to create a thin cap of corneal tissue. This cap was laid aside and then a second cut was made to the remaining cornea. This second cut was the one that allowed someone’s refractive error (for example their near-sightedness) to be reduced. The cap was then repositioned and the eye allowed to heal. The problem with this procedure was that it was very difficult to make the second cut in a reproducible way on different patients. Therefore, it was difficult to predict what the results of the procedure would be on any given patient. In PRK, the excimer laser is used to reshape the corneal surface in what has proven to be a predictable fashion. Several years ago the idea arose to use the excimer laser to perform the second part of the ALK procedure. Instead, it is left attached by a hinge of normal corneal tissue and folded safely back out of the way. The laser is then applied to the remaining cornea. The cap is then repositioned and allowed to seal itself in place. In the typical procedure this does not require the use of stitches. By not completely removing the cap it is much easier to return it to its appropriate orientation on the cornea.
Does LASIK Work?
LASIK has allowed many individuals to function with a greatly reduced dependency on glasses and contact lenses. However, this procedure is not necessarily for everyone. The key as to how well one might be predicted to do with this procedure depends on several factors including their refractive error (eyeglass prescription), the health of their eyes and their expectations. Most individuals (95%) that are considered to be good candidates will achieve an uncorrected vision (vision without glasses or contacts) of 20/40 or better. As you may well know, many of these patients were functionally blind at a distance when they didn’t wear corrective lenses prior to having LASIK.
An important point to understand is that while LASIK has the ability to correct several types of refractive errors, it cannot correct presbyopia. Presbyopia is the phenomenon that occurs to every person some where around the age of 40. This is where the eye loses it ability to increase its focusing power to allow one to read up close. This is a normal aging process and happens to all of us regardless of whether we are nearsighted, farsighted or never needed glasses for distance our entire lives. This is why one has to resort to reading glasses or bifocals. There is no reliable procedure available to correct this.
Who Is A Candidate?
LASIK is being used to help people who are nearsighted (myopic), farsighted (hyperopia) and with astigmatism when combined with one of these others in an appropriate amount. Of great importance is that one’s prescription has been stable for one year. The patient must be at least 18 years old for myopia and 21 for hyperopia and astigmatism. There truly is no upper age limit, although if someone is close to needing cataract surgery we advise against having any refractive procedure as quite often the problem can be addressed through the cataract operation.
For myopia the general range that can be treated is �"1.00 to �"10.00 or perhaps �"12.00. The upper range will depend on the individuals corneal anatomy and their expectations both of which are determined as part of the pre-operative evaluation. There can be up to 4.00 diopters of associated astigmatism.
For hyperopia the range is +1.50 to +6.00 with less than or equal to 1.00 diopter of astigmatism.
There are a few eye diseases, as well as systemic (general) disease that would make one a poor candidate for refractive surgery of almost any kind. These are best discussed with your eye doctor.
What are the possible side effects or complications?
While LASIK is very effective and most patients do well, it is important to remember that it is a real surgical procedure. Like any surgery there are always some risks to consider. Any person considering refractive surgery should carefully weigh for themselves the risks versus the increased freedom and quality of life they stand to gain from a decreased dependence on corrective eyewear.
What is it like to have LASIK?
Rarely does anyone describe having had LASIK as painful. All the anesthesia that is required is anesthetic drops like the ones that we use in the office when we examine patients. Patients will occasionally report a pressure feeling or burning, but, it is almost always mild. The choice whether to treat both eyes on the same day or separately is generally left up to the patient unless we identify some clear reason to favor one approach over during the preoperative evaluation. It takes approximately 15 minutes to treat one eye. This includes the time it take to prepare the eye for surgery and the actual surgery itself. The creation of the corneal flap takes only a few seconds. The length of time the laser portion of the procedure takes will vary depending on what type of treatment is being preformed. However, this generally runs less than a minute for even large treatments. Post-operatively there is usually very little pain. Patients describe a sensation as though a hair was in the eye or perhaps a contact, but, rarely is it debilitating. A shield is worn over the eye on the day of surgery and left on until the person is seen the next day in the office. After that, you will be asked to wear the protective eye shield when you go to sleep for 2 weeks. During the day none is required. You will be asked to use medicated eye drops for 7-14 days in addition to artificial tears. No eye makeup can be worn for two weeks and we ask you not to participate in activities that may result in result trauma to the eye for 2 weeks. Most patients will see a rather dramatic improvement in their vision from the first day after surgery which will allow them to drive. However, it is not uncommon for your vision to fluctuate for several weeks after surgery.
How can I find out if I am a candidate?
We offer free screenings for people interested in refractive surgery. These may be arranged by calling 779-3070. You will be seen by our refractive surgery coordinator who will check your refractive error and perform some crucial tests that are required to properly evaluate the suitability of any candidate. You will be presented with a great deal of information regarding the procedure. This evaluation, while not a complete eye exam, will generate much data about your eyes and takes about an hour to complete. If you decide you would like to pursue the decreased dependence on corrective lenses that LASIK offers, you will be scheduled to see one of our surgeons who perform the procedure. The surgeon will perform a thorough eye exam and review all the data generated in the screening. After carefully reviewing all of the data and understanding what your goals and expectations are for refractive surgery, it is the physician who determines whether or not you appear to be a good candidate for LASIK.
Refractive surgery has given many people the freedom to enjoy life without the burden of corrective eyewear. For many it is the first time in their lives they have been able to wake up from sleep and see. They can now play sports, swim or simply work around their homes without the annoyance of glasses that slip or fog or get coated with sweat. The no longer have to tolerate contact lenses that dry out and irritate their eyes. If you would like to explore the possibility of a life without the constant need for corrective eyewear, this free evaluation may be the first step on the road to an improved quality of life.
Cornea-The cornea is the transparent portion of the eye through which light passes on its way to the retina. It is this portion of the eye that has been the target of most refractive procedures.
Sclera-The sclera is the white part of the eye. It is the outer wall of the eye.
Conjunctiva-This is a thin transparent tissue that covers the sclera. It contains blood vessels and some of the tear producing cells of the eye.
Iris-This is the colored portion of the eye. For instance when one looks at a blue or brown eye, it is the iris that gives it its color.
Pupil-This is the black hole in the center of the iris. It is nothing more than an empty hole through which light can pass to the back of the eye. The pupil changes its diameter (size) depending on the amount of light present. The pupil size changes as a result of the iris constricting or dilating (closing or opening).
Lens-This is situated behind the iris. The lens and the cornea do most of the focusing for the eye. The lens has the ability to change its focusing power depending on where you are trying to see. As we grow older the lens gradually loses this ability and around age 40 we start to notice difficulty reading up close. This worsens with age and happens to everyone. It is the lens that becomes a cataract. When the lens loses its normal clarity and becomes yellow or cloudy we call it a cataract.
Retina-The retina is like the film in a camera. It collects the light impulses that pass into the eye and sends it to the optic nerve. Most of the retina is devoted to peripheral vision which is not fine detail. When we try to make out detail the brain automatically aligns the eyes so that the incoming images are directly focused on the macula.
Optic nerve-This is the "cable" that connects the eyes to the brain. All the light impulses are sent to the brain via this nerve.
Brain-There are areas of the brain devoted to sight. Images are collected in the brain and interpreted as being things that we recognize. Therefore it can be considered the final part of the visual pathway. Damage to these areas can result in difficulty with vision even though the eyes themselves may be perfectly healthy.
Refractive Errors
When someone requires corrective lenses to see (glasses or contact lenses), they are said to have a refractive error in their eye. The different types of refractive errors are explained below.
Myopia=Nearsightedness: Your best point of focus without any type of lens in front of your eye is close to you. In other words, without correction you cannot see off in the distance, but, you can read if you hold the material close enough.
Hyperopia=Farsightedness: Your best point of focus without lenses is off in the distance. But, as you try to focus on things that are closer than far off they get blurry. It gets more blurry the closer the object is to you.
Astigmatism: People with astigmatism have an irregular shape to their cornea. This tends to make objects blurry both up close and at a distance.
Many individuals have a combination of myopia and astigmatism or hyperopia and astigmatism.
Presbyopia: This is a condition that everyone will experience at some point in their lives. Typically, it occurs around age 40. We start to notice that although our distance vision hasn’t changed, now we have difficulty reading up close. In order to bring near objects into focus the eye has to increase its focusing power. As we get older we lose the ability to generate the required power. In someone that has never required glasses for distance vision, they will now start to need reading glasses. In a nearsighted person they will still be able to read without lenses in front of their eyes because that is where their best point of focus is. However, when they put their lenses on they can’t read although their distance vision is unchanged. A farsighted person will notice that while their lens used to allow them to both read and see at a distance, now they require additional power to read at near. We currently have no effective procedure for this condition.