LASIK is the acronym for laser in situ keratomileusis, sometimes referred to as laser assisted in situ keratomileusis. The name refers the use of a laser to reshape the cornea without invading the adjacent cell layers. In situ is Greek for "in the natural or normal place." Medically, in situ means confined to the site of origin without invasion of neighboring tissues. Kerato is the Greek word for cornea and mileusis means "to shape."
Dr. Stephen Trokel published the first paper on laser assisted corrective surgery
in 1983. In 1985, the first phototherapuetic karatectomy
surgery was performed, and in 1987 the first photorefractive keratectomy (PRK) was performed, accidentally, on a blind
patient by one Dr. McDonald. After performing trials on the patient, the patient's vision was miraculously restored to 20/20 and stayed there for years. In 1988, McDonald performed the first PRK
on a patient with sight, during an FDA
approved trial. Since then, the emphasis has changed from PRK to Lasik
, which is very similar, even the laser is the same, except Lasik uses the laser to create a fold in the epithelium
of the eye(mentioned several times above) in the eye, whereas in PKR, the laser
is used to simply scrape off the epithelium. Both techniques are still in use today.
How well does Lasik perform versus various eye problems?
93% of patients with Myopia
(near-sightedness) received 20/40 vision or better. 50% achieved 20/20 or better.
Patients with High myopia (really bad near-sightedness) experiences a higher incidence of regression and complications. Consult with physician.
Patients with Hyperopia (far-sightedness) will experience slightly more regression, but can expect basically the same results as those with Myopia.
Once again, people with High hyperopia can expect similar results to those with High myopia.
Because the same basic Lasik procedure is used on all patients, those who heal faster or slower than the average may experience a slight over or under correction. Also, they may experience some regression because of changes in the shape of the cornea.
In about 1% of cases, DLK (Diffuse Lamellar Keratitis), a non-infectious inflammation under the cornea, may occur after 1 to 3 days. Doctors have several hypotheses, but are ultimately unsure of the causes. You will not feel the symptoms, and only a doctor will notice DLK. If caught early, DLK can be fixed easily and no vision-loss will occur. It is therefore imperative to keep up your scheduled visits to the doctor.
As was mentioned in some of the previous w/us, wrinkles can occur in the fold that is created by the procedure. Usually they cause no problems and can be ignored, but about 1 in 100 of patients experience one that causes a vision problem, and has to have it corrected. This wrinkling can be caused be rubbing your eyelid before the fold has a chance to fully reattach, poor positioning of the fold, and can also be caused by unknown causes. This occurs more frequently in patients with high myopia than other types.
Yet another complication can be caused by epithelial (skin) cells growing under the flap. This complication varies from doctor to doctor, so you should ask your doctor personally about the incidence he sees. One study reported a whopping 14% with this problem, while others may see only 3 or 4 in a thousand. Sometimes this complication doesn't need to be opperated on, but this isn't always the case. Doctors can prescribe eye drops to minimize the incidence of this happening.
Something that EVERY person who looks into Lasik should be aware of is that while your eye chart vision (ie 20/20, etc) may be much improved, you could very well experience a loss in contrast, night vision, and low-light sensitivity (dmd experienced this).
We have found two independent studies that note subjective reports of reduced night vision. First assessed 174 eyes that were treated between November 1997 and October 1998. Of them, 29% reported reduced night vision - however, it's important to note that 97% of patients indicated they would decided to have LASIK again.9 The second involved questionnaires sent to 50 patients; 8.8% reported difficulty with nighttime driving.10 Again, 98% noted overall satisfaction with their outcomes. The "Summary of Safety & Effectiveness Data" required by the US FDA tabulates the subjective reporting of glare, halos and difficulty with nighttime driving pre-operatively and post-operatively at various time intervals
Lastly, dry eyes after the opperation is a common occurence. 50% of people reported dry eyes at some part of the day 3 months after surgery. It has been noted by a few doctors that while other complications have been decreasing in frequency, dry eyes is increasing.
Lasik is done using an excimer laser
, and the procedure itself has been described above. Two types of lasers are used, broad beam
. Scanning is further subdivided into slit scanning
and spot scanning.
Most patients wouldn't notice a difference between any of the types. A description is provided by Dr. Stanley Teplick:
- Broad beam Laser - A broad beam laser uses a relatively large beam diameter (from 6.0 to 8.0 millimeters) that can be manipulated to ablate the cornea. The broad-beam laser results in the shortest procedure time. This speed creates less likelihood of overcorrection and decentration — a complication caused by movement of the pupil. A disadvantage is an increased possibility of center islands — a complication related to ablation. However, ophthalmologists have learned to decrease the incidence of center islands by using several short laser pulses to ablate the cornea instead of one longer one.
- Slit Scanning Lasers - A slit scanning laser uses relatively small beams linked to a rotational device with slit holes that can enlarge. During surgery, the laser beam scans across these holes to gradually increase the ablation zone. A uniform beam and potentially smoother ablations characterize slit scanning lasers. Disadvantages include a slightly higher propensity for decentration and slightly greater risk of overcorrection.
- Spot Scanning Lasers - These systems have the potential to produce the smoothest ablations and use radar technology to track the eye's movement. They also have the potential to treat irregular astigmatism and link to topography. These lasers must be linked to eye tracking to ensure proper centration.
Finding the Right Doctor
Find out how many operations your doctor has performed, they really do get better over time. You will probably NOT want to go to a newbie
doctor. Check to see the type of laser your doctor uses, some may use lasers not approved by the FDA, or even bought cheaply on the black market
. This is important. Make sure your doctor is informative
Remember that the doctors are messing with your eyes, the windows of the soul
. Research every single thing you can find so you can make an informed decision. Don't be afraid to look around at different doctors, just because they do the same procedure does not mean that the results will always be the same. Be aware that even if the doctor does a perfectly fine
job, things can still go wrong, complications beyond anyone's control can still occur, and you may still end up unsatisfied
with your surgery. In the end, it's a decision
you have to make.