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A Frame-capable browser can be gotten from Netscape Communications. Laser Assisted in-Situ Keratomileusis, (LASIK) also known as Laser Intrastromal
Keratomileusis, combines the precision of the Excimer laser delivery system with the benefits
of Automated Lamellar Keratoplasty.
One of the crucial elements of this surgery is an
instrument called a microkeratome. This device was first
invented by Dr. Barraquer of Bogota, Columbia, for
use in keratomileusis. Years later his associate Dr. Luiz
Ruiz refined the instrument to be used for lamellar
procedures. During the surgery a part of this instrument
called a suction ring is used to isolate the central part of
the cornea. The microkeratome than glides across the
cornea creating a smooth corneal flap (lenticule). This flap should remain attached or
"hinged" to the cornea. Then, in less than 90 seconds, ultraviolet light and high energy pulses
from the Excimer laser reshape the internal cornea with accuracy up to 0.25 microns. The
procedure can treat low to high levels of nearsightedness and by adjusting the pattern of the
laser beam, it may also be possible to treat farsightedness and astigmatism. The amount of
tissue that is vaporized depends upon your refractive error or degree of nearsightedness.
After the cornea has been reshaped, the flap is replaced in its original position.
Because of the cornea's extraordinary natural bonding qualities, healing is rapid and does not
require stitches. The entire procedure takes less than 10 minutes. In the United States,
LASIK is still considered "investigational" by the FDA, but is quickly becoming the
procedure by choice of refractive surgeons all over the world.
Laser Assisted in-Situ Keratomileusis (LASIK) is a safe
and effective procedure used to reduce large amounts of
myopia, but it is a surgery and thus has risks involved.
These risks are undercorrection, overcorrection,
inflammation, infection, loss of tissue which would have
to be replaced by donor tissue, and even loss of vision.
Be sure that you are fully informed of all the benefits and
risks of LASIK. Also make sure you choose a surgeon
with a lot of experience in lamellar procedures (ALK).
History of Refractive Surgery
There has been an interest in refractive surgery for almost 100 years. The basic principles of
radial keratotomy were laid out as early as 1898 by Lans, a Dutch professor of
Ophthalmology. In Japan, in the 1930's, Sato did some pioneering work in corneal incisions.
He placed incisions in the endothelial surface of the cornea as well as the epithelial surface,
but this technique resulted in late corneal decompensation for many of his patients. It took the
observations of Dr. Fyodorov of Russia, in a case of eye trauma in the 1970's, to bring about
the practical application of refractive surgery through radial keratotomy.
Fyodorov was treating a boy whose glasses had broken, causing corneal lacerations.
Following recovery, this patient's refraction was significantly less myopic than prior to the
injury. This discovery prompted Fyodorov to research past efforts at refractive surgery, and
he worked out a formula which made this procedure more predictable then it had ever been
before. In 1978 American Ophthalmologists became interested in these findings. Dr. Leo
Bores was the first to bring the technology back to the United States after visiting Fyodorov
in the Soviet Union.
Since it was introduced, radial keratotomy has been performed on over 2 million patients in
the United States alone. The myopic public has shown a great interest in refractive surgery.
Some limitations of radial keratotomy prompted research into alternate forms of refractive
Working in the IBM research laboratories, a Dr. Srinivasin saw the potential of the Excimer
laser in interacting with biological tissue. Dr. Steven Trokel, an ophthalmologist, finally made
that connection to the cornea. This laser machine emits a nonthermal cold beam that upon
interaction with corneal tissue breaks the carbon-carbon bonds between molecules thus
causing tissue ablation. The first patient to have photorefractive keratectomy was treated in
Germany in 1988. As of November 1994, it is estimated that over 1,000,000 PRK cases
have been performed in 40 countries around the world. With the number of cases rising
exponentially, especially in Europe and East Asia, and with new refractive technologies being
actively developed, we feel confident in saying that refractive surgery is here to stay.
ALK (Automated Lamellar Keratoplasty)
Automated lamellar keratoplasty, or ALK, is a surgical procedure used to correct high
degrees of nearsightedness, or myopia, and low to moderate amounts of farsightedness, or
hyperopia. The surgery is performed with an instrument called an automated keratome, and
affects the shape of the cornea, or window of the eye, to achieve the correction.
This surgery is a more streamlined and effective version of a surgery called keratomileusis,
which was first performed in the United States in 1964. ALK can correct from about -5.00
dioptres up to -30.00 dioptres of myopia and about +1.00 dioptres to about +4.00 dioptres
of hyperopia. The surgery for hyperopia is performed much less often than the surgery for
myopia, because high myopes have a greater improvement in both amount and quality of
vision, and the results for myopia are more predictable.
During the surgery, a special instrument is used to isolate
the central part of the cornea. A thin layer is sliced off of
the center of the cornea. This layer, called the
lenticule, should remain attached or "hinged" to the
cornea to allow reattachment in the same position. In the
surgery for myopia, the settings on the instruments are
changed at this point, and a second thin button of tissue
is removed from the cornea and is discarded. The
hinged lenticule is then replaced in a way that makes it stick without the use of stitches. The
removal of the piece of tissue can flatten the front of the cornea significantly, which allows for
correction of large amounts of nearsightedness.
The thickness of the layer shaved off is of critical importance, because these calculated
amounts are what predict the amount of prescription correction. Surgery calculations with a
skilled eye surgeon, or ophthalmologist, should also be based upon corneal thickness,
amount of glasses prescription, and predictions from mathematical tables, or nomograms,
specifically designed for ALK.
Unlike other keratorefractive surgical procedures, age does not currently appear to be a
factor in the results achieved with ALK. As with other surgical procedures, you should seek
out an ophthalmologist with the most current technology and information and an excellent
success rate, i.e., patients who are pleased with their results. This will give you the most
predictable results for your ALK surgery.
The goal of automated lamellar keratoplasty is to significantly
decrease a large prescription so that thinner glasses or no
glasses need to be worn. The procedure can make you much
. more functional without glasses. However, if the full correction
is not achieved with ALK alone, more correction is still
possible. Three to six months after the ALK, further
correction can be obtained with a secondary radial keratotomy (RK) and/or astigmatic
keratotomy (AK) procedure.
Automated lamellar keratectomy is a safe and effective procedure to reduce large amounts of
myopia, but it is a surgery and thus has risks involved. These risks include undercorrection,
overcorrection, inflammation, infection, loss of tissue which would have to be replaced with
donor tissue, and even loss of vision. Be sure that you are fully informed of all the benefits
and risks of ALK before you have the procedure performed by a well qualified surgeon. The
surgery is performed under local anesthesia (you are awake), and it is done on an outpatient
basis (you go home the same day).
In about 20 minutes you can have dramatically improved
vision with LASIK, an advanced Laser procedure. We can
correct astigmatism and advanced levels of nearsightedness
and farsightedness with the preciseness of the Excimer
Laser. In about 20 minutes you can have dramatically improved
vision with LASIK, an advanced Laser procedure. We can
correct astigmatism and advanced levels of nearsightedness
and farsightedness with the preciseness of the Excimer
LASIK is "Laser Assisted in-Situ Keratomileusis." It is
a combination of surgical skills and the technology of the
Excimer Laser that reshapes the surface of the cornea to
correct problems with vision.
LASIK can correct nearsightedness, farsightedness and
astigmatism at levels not possible with earlier refractive
surgery techniques. If you considered eye surgery in the
past, but felt that it wasn't right for you, you'll be delighted
with the exciting difference of LASIK!
Preparing for LASIK:
The results you achieve from having LASIK first require
a very thorough examination to rule out any disqualifying
conditions. Since LASIK involves only the surface of the cornea, and
since LASIK can correct a range of vision from slight to
extremely poor, almost all exams result in a "Thumbs Up."
First, to benefit from LASIK, your vision prescription must
be stable. This requirement rules out young persons whose
shape of the eyes is still maturing. There are conditions
such as being pregnant, having glaucoma and other medical
and eye disease problems which can exclude you as a
One of the tests you'll take is a computerized
topographical mapping of the surface of the cornea. This
three dimensional multi-color map of the surface provides
key measurements for the Excimer Laser. After the LASIK
procedure, a map will then depict a changed surface, one
that correctly focuses images on the retina, allowing you to
WHY SHOULD I CHOOSE LASIK?
Patient satisfaction with LASIK has been extraordinarily high. This precise treatment helps the eye focus
properly, thus decreasing or diminishing the need for glasses or contact lenses.
Since the ophthalmologist applies the laser directly to the corneal bed the healing process is rapid. You
will experience minimal post-operative discomfort and your vision will be restored quickly.
Although LASIK is still being performed on an investigative basis in the United States, it is used as routine
treatment for low to moderate myopia around the world. LASIK can also be used to correct severe
myopia. Hyperopia can now be corrcted as well.
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Vision Correction via LASIK
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LASIK stands for “laser-assisted intrastromal in-situ keratomileusis,?a vision correction procedure in which a flap of 160-180 microns depth is cut in the front of the cornea, the flap is folded back to expose the stroma of the cornea, an excimer laser ablates (reshapes) the exposed stroma, and the flap is folded back down. The anterior layers of the cornea (epithelium, Bowman’s Layer) are preserved (unlike in PRK, in which Bowman’s Layer is burned away by the laser and does not grow back), and there is much less post-operative pain than with PRK, as well as lower incidence of dry eyes, hazing, and scarring. Healing time is much faster than for RK or PRK, and patients can see right away (I was seeing 20/25 the very next day, and 20/20 a couple of days later). The surgery corrects myopia, hyperopia, and astigmatism, but cannot fix presbyopia. If you needed reading glasses to see up close beforehand, you’ll still need them afterwards (unless you opt for monovision, but you may still need the readers anyway).
LASIK just recently began to be practiced in the U.S. in 1996. It has been done for years in Canada and in Colombia, where it is now routine. The U.S. equipment is (in my opinion) inferior to that offered elsewhere, but is catching up in some cases (the Autonomous Technologies laser, with automatic eye-tracking, is at least comparable to the Chiron 217, but the capabilities of the two lasers may not completely overlap).
LASIK was invented in Colombia by Drs. Virgilio Galvis and Luis Ruiz, who followed the earlier work in keratomileusis of Dr. Jose Barraquer, who is considered to be the “father of modern refractive surgery.?Galvis’s clinic claims to be able to treat myopia as bad as -25 diopters (D), hyperopia as bad as +17D, and astigmatism as bad as 9D (note that higher myopes may not get 20/20 vision, but they will be improved dramatically). (NOTE: A patient’s correction for extreme cases is highly dependent upon available corneal thickness. One must have a deeper ablation to correct higher errors, and it is not safe to leave less than about 250 microns of untouched tissue. Note also that the higher the correction, the smaller the fully-corrected zone may have to be, because wider ablations must be deeper, all else equal.) These claims are from Dr. Friedman’s page, and echo the laser manufacturer’s claims. I do not know if Dr. Galvis actually attempts corrections as extreme as those claimed. TLC’s claims are slightly more conservative, and they explain why at their web site.
By comparison, the most advanced machine approved by the FDA in the U.S., the VISX laser, is only approved for treating myopia of -1 to -12D and astigmatism of 1 to 4D. Many U.S. clinics that do not possess the VISX laser are using “astigmatic keratotomy?(AK) to correct astigmatism—this is similar to radial keratotomy in that a surgeon makes an incision into the cornea. I have to ask—if there are lasers available that will do the correction without using a scalpel, then why allow yourself to undergo AK?
The VISX (even the new S2 machine) and Summit machines are broadbeam-type lasers, which use expanding cones of laser light to treat the cornea, and are limited to ablations of 6mm in diameter. Not all of this 6mm will be corrected to full power. Mild corrections may get a central zone of 3-4mm that is fully-corrected, with the rest blending upward to make a “ramp?to the (uncorrected) rest of the cornea, while stronger corrections may have a central zone of only 1-2mm, with the rest being blending. The reason for this, as explained above, is that more tissue must be removed for stronger corrections, so they will be deeper and will need a larger blending area to minimize edge transition effects that might occur were light to hit a sudden “step?where the corrected zone met the uncorrected zone. These lasers are currently used only for correction of myopia and astigmatism.
If the surgeon doesn’t take some pauses during treatment with a broadbeam laser to allow the plume created from ablation to dissipate, a “central island?may form, which means that not enough tissue was ablated in the very center of the cornea to provide full correction. Central islands often resolve themselves after a few months, but they sometimes require an enhancement to make them go away.
A potential artifact of the 6mm limitation is that patients who have large pupils in dim light may experience glare, arcs, starbursts, and halos at night, and may also suffer from night myopia because their eyes are gathering too much light from the uncorrected and blended parts of their corneas in comparison to the central corrected zone. Yes, that’s right—some PRK and LASIK patients need glasses to see clearly in dim light. Your surgeon should disclose this to you, if he’s honest.
The other kind of laser is the “scanning-slit?or “flying spot?style of laser. These lasers use a 2mm or smaller beam of light that is scanned around the cornea in a preprogrammed fashion to produce the correction. They are capable of ablations larger than the 6mm used by VISX and Summit, and many people claim that they produce smoother, more accurate ablations. Because they offer a larger treatment zone (for those patients with adequate corneal thickness), night vision artifacts are minimized (but the risk of having them is still nonzero). These lasers are in widespread use outside of the U.S., and most incorporate some kind of automatic eye-tracking to compensate for involuntary eye movements. Examples are the Chiron 217, Nidek, and Autonomous Technologies machines. Automatic eye-tracking has only been approved for one manufacturer (Autonomous Technologies) in the U.S. One group in Minnesota was doing investigational work with a Chiron 117 (the precursor to the 217, but itself a broadbeam laser) but was not permitted by the FDA to use the eye tracker on human patients. Scanning lasers can correct myopia, astigmatism, and hyperopia.
There is some development going on with solid-state lasers that work on a wavelength of 213nm instead of the 193nm that is used by Argon/Fluorine gas lasers such as Summit, VISX, and Chiron. Early tests by the FDA indicate that the 213nm lasers will do more “collateral damage?to surrounding corneal tissues than the 193nm lasers do. I would stay away from solid-state 213nm lasers if I were you.
The latest research is in the area of linking corneal topographies directly to the laser to produce custom ablations for each patient. Currently, there are preprogrammed treatments for each refraction, and they treat a prototypical “average?corneal shape for that refraction. The topo-linked lasers offer the promise of treating each patient’s unique idiosyncrasies, and may be able to treat patients who have irregular astigmatism (either naturally-occurring, or induced from previous unsuccessful refractive surgery). As of this writing (August, 1998), topo-linked lasers appear to be about two years away from mainstream use.
I sometimes get questions about LASIK for mild myopia. The biggest risk is a 1% chance of induced irregular astigmatism from an irregularly-healed flap (provided you choose an experienced surgeon). This complication can cause permanent loss of from one to four lines of best-corrected visual acuity, or BCVA (i.e., if you saw 20/15 with your glasses before surgery, then even though you may see 20/70 unaided after surgery, you might not see any better than 20/40 with glasses after surgery. That’s a significant blur, and anyone who tries to brush that risk under the rug is doing you a vast disservice. You might get relief from rigid gas-permeable lenses in this case, but if you’re one of the extraordinarily unlucky few with severe induced irregular astigmatism, you won’t. about this risk, and do not attempt to hard-sell you. The decision is yours to make. By the by, the risk increases to about 2.1% for myopes worse than -6.00D). If you already see very well with glasses or contacts, and see at least well enough to function reasonably well without them, then I would NOT get LASIK if I were you. Obviously, this cutoff point is subjective, and each person has to decide for himself if the expected improvement is worth the risk. I’d set a hard limit at 20/40 (the legal driving limit, representing, on average, -0.50D to -0.75D of spherical refractive error), and a softer limit at about -2.00D. Myopia this mild is very easily corrected with lightweight glasses or contact lenses. Of course, the presence of a lot of astigmatism changes things, but in the end, only you can decide if the risk is worth it.
Some surgeons prefer to treat patients with myopia less than a certain amount with PRK rather than with LASIK, in order to eliminate the risks from flap complications. This is a personal decision between the you and your surgeon, but you should be aware that PRK carries markedly greater risks of permanent haze and scarring and a much larger infection risk than does LASIK. The risk of permanent haze and scarring increases markedly with the attempted correction, and is most often seen when PRK is attempted on patients whose initial refractive error was greater than -4.00D. The infection risk is not dependent on the amount of correction required. Furthermore, PRK patients are more likely to experience post-op pain, and take considerably longer to heal enough to have useful vision. This is balanced against LASIK’s 1% to 2% risk of flap irregularities that cause loss of BCVA, and which might not be correctable until the topo-linked lasers come on-line. (For mild irregularities, rigid gas-permeable lenses may help, but there are no guarantees. Note also, that a botched PRK may also result in irregular astigmatism that can significantly interfere with your daily life. There have been a few patients of both PRK and LASIK on the USENET newsgroup sci.med.vision who have had their lives significantly affected by bad outcomes—in one case, the patient is nearly suicidally depressed.)
ALK, or automated lamellar keratoplasty, from which LASIK was developed, is now obsolete. I do not believe there is any legitimate use for it anymore. Similarly, RK, or radial keratotomy, in which radial cuts made by a diamond scalpel are used to flatten the cornea, is unconscionable now that laser techniques are available. The scarring from RK is horrible, the night vision is atrocious, and there is a very real risk of corneal rupture if the eye receives a blow (there is one noteworthy case of a police officer who had RK and whose cornea ruptured when his car’s airbag deployed!). A great many patients experience “hyperopic shift,?in which they get progressively more and mor farsighted. To a myope, that might sound like a good thing, until you realize that you’ll need thicker and thicker glasses to be able to use your computer, read labels at the supermarket, and read books and newspapers. RK is bad news. Run, don’t walk, away from anyone who wants to treat you with RK.
I first had LASIK performed in mid-June of 1997. The surgery was performed using a Chiron Automated Corneal Shaper (the microkeratome that cut the flap), set to cut the flap at 180 microns, and a VISX Star. This was before I had discovered sci.med.vision and learned the limitations of that machine.
My right eye, and corrected it from -5.50, -0.25 to about +1.00,-0.25 initially (overcorrection is done to compensate for the regression that occurs during healing. Surgeons try to be conservative so that you end up right at 0.0 or slightly myopic.). Over a few days, this improved dramatically as the corneal edema went away, and I was seeing 20/20. I wore a soft contact lens in my left eye to provide balanced vision. After a month or so, I began regressing more and more myopic, and could only see 20/50. Clearly, I would need an enhancement. ( NOTE: enhancements have the exact same flap risk of irregular healing and resultant loss of BCVA as does the initial LASIK procedure.)
The surgery went without a hitch, and the Ativan I had been given kept my nerves well under control. After about 20 minutes in the waiting room, my flaps were examined under the slit lamp and I was sent to my hotel (my wife drove), where I slept for several hours. When I awoke, it was dark outside, but I could see very well to go to dinner, with no glare, arcs, starbursts, or halos. The acuity was startling and crystal clear—I could see as well as my wife, if not a little better (she has natural 20/20 vision, and can read 20/15 in strong light). When checked the next day, I was +2.00D, 0.0D in my left eye and +1.00D,0.0D in the right. Over time, this overcorrection has reduced, and I am now about +0.25D in each eye, with about -0.25D of residual astigmatism in my right eye. I have no night vision problems, except perhaps when I am extremely tired and my eyes are dry (then I see some small starbursts). In fact, on the way home from surgery, I made a game out of trying to read the mile markers on the Ohio Turnpike before my wife could (in some cases, I could!).
* Beyond about 20/400, Snellen Acuity measurements are pretty meaningless. I gauged this based upon a homemade Snellen chart with some really huge letters.
|OS: -6.00D, -1.50D
OD: -5.50D, -0.25D
|First surgery; right eye only, after healing
|OS: -6.00D, -1.50D
OD: -1.50D, -0.25D
|Right eye enhancement; left eye original treatment, as of May, 1998
|OS: +0.25D, 0.0D
OD: +0.25D, -0.25D
|Followup to above entry, as of November, 1998
|OS: +0.25D, -0.50D
OD: +0.25D, -0.50D
** In good light, I can almost pick out 20/15 on my homemade chart when I’m well-rested and well-hydrated.
Of course, I am very happy with my results, BUT THERE ARE NO GUARANTEES THAT YOUR RESULTS WILL BE THIS GOOD. The odds are in your favor, but the risks are nonzero, and not everyone who has a successful surgery ends up with unaided 20/20 vision. 95% of all LASIK patients get 20/40 or better (some require an enhancement to get there), for reference. The chances for 20/20 improve as initial refractive error decreases. .
Prior to the procedure itself, your local O.D. will have screened you for eye diseases, keratoconus, or retinal problems, all of which disqualify you for surgery. He will also have performed a cycoplegic refraction, in which he gave you drops to paralyze your eyes?ability to accommodate, so that he can get a very accurate refraction. You should have ceased wearing soft contacts for at least one week prior to this exam, and hard contacts for at least four weeks, and you may not wear them again between the exam and your surgery (they can leave some residual misshapenness in your cornea that can cause inaccurate surgery). When you arrive at your laser center, a map, called a corneal topography, will be made of your eye. This map will be used to help the laser select a program, called a nomogram, to tell it how many pulses to deliver to various spots on your cornea to produce the intended correction.
Your refractive error will be double-checked, possibly by using an autorefractor, but definitely by hand with the phoropter (that funky mask-shaped device your eye doctor uses to determine your prescription).
You will be given drops to anesthetize your cornea, and measurements will be made by tapping your cornea with a pachymeter to determine your corneal thickness. You’ll see it, but you will not feel it. FYI, average corneal thickness is about 500 microns at the center, tapering to about 300 microns at the edges.
If any of the above checks are omitted, get up and leave! They are vital safeguards to make sure that you have a safe surgery with the best possible chance of a good outcome.
You will be given more numbing eye drops, and your face will be washed with an antibiotic cleanser. You’ll also receive antibiotic eye drops and either diazepam (the generic name for Valium) or iorezepam (the generic name for Ativan) to help you calm your nerves. I strongly suggest that you accept the medication, but make sure that you don’t take too much, because you need to be awake during the procedure! (Note contraindications for these medicines, however—your surgeon should be aware of them).
You will lie in the operating chair, which is motorized and will draw you up under the operating microscope and laser. The eye that is not being treated at the moment will be taped shut, and your operative eye will have its lashes taped back with a surgical drape. You will be given much more powerful anesthetic drops (usually Tetrocaine, a cocaine derivative). These sting a little until they take effect. The surgeon will ask you if you can still feel the stinging, and will continue to apply the drops until you can’t. Don’t be a hero! Your cornea is very sensitive, so make sure you get all the medication you need so that you feel nothing when your cornea is touched. Then the surgeon will insert a speculum to hold your eyelids open. Relax and do not fight with the speculum. Do not squeeze it with your eyelids, just relax. Your relaxation (and the fact that you do NOT squeeze with your eyelids—ask your surgeon to give you guidance and feedback on this during the procedure, because you won’t realize you’re doing it) is crucial to getting a good cut when the flap is made (this is why you should accept the tranquilizers unless there’s a medical reason not to).
A couple of reference marks will be made on your cornea with a soluble ink. These are made so that the surgeon can properly realign the flap when he’s done. This happens very quickly—if you aren’t watching for it, you’ll miss it.
The suction ring will now be placed on your eye. It surrounds your cornea, and applies pressure to your eye so that the cornea is easier for the microkeratome to cut. About 60mmHg of pressure is applied (this is 3 to 6 times normal eye pressure, so if you have glaucoma or retinal problems, you should definitely bring them to your doctor’s attention beforehand, as this part of the surgery may be dangerous for you), and your vision blacks out. Do not worry! Your vision will return as soon as the suction is released, which will be only 10-30 seconds after it is applied! Make sure your doctor tells you when he’s about to start the microkeratome. Concentrate on breathing normally, to the exclusion of all else. This will help you control your nerves, if you happen to still be nervous. You must hold as still as you possibly can, and must avoid flinching, which will produce a bad cut. If you get a bad cut, the surgeon should smooth the flap back down, let you heal for three months, and then try again. He should not attempt to perform the laser part with a bad cut, because you will get a bad result. Don’t worry about this, and don’t clench your body up. If you just concentrate on taking regular, deep breaths, you won’t even notice that the cut has been made .
Thanks to your concentration on your breathing (normal, deep breaths) and the tranquilizers, you’ve controlled your nerves, and the surgeon has made a good cut. He removes the microkeratome and flips back the flap. Congratulations! You’ve just made it through the most difficult part of the procedure, and it was over in less than 30 seconds. You can see, but what you see is a blurry light (red for VISX, green for the Chiron 217) upon which you must try as best you can to stay focussed while the laser operates. The assistant will give you a running count of how many seconds of treatment are left, and many surgeons will take a pause every dozen seconds or so to wipe away any debris on your cornea and present a clean surface to the laser (this practice minimizes the risk of central islands and uneven treatment).
When the laser is done, the surgeon will rinse your cornea, then smooth the flap down with a tiny Weck cell sponge. He’ll spend some time and care with this, because it is critical to your final outcome. Then you will lie there for a few minutes while the cornea beds down, you’ll get more antibiotic drops, and the surgeon will remove the speculum when he is satisfied that your cornea is smoothly in place. Then the procedure is repeated on your other eye (unless you have chosen to have only one eye done at a time, which is rare but not unreasonable).
After the procedure, you’ll suddenly feel heavy and sleepy. Your adrenaline and anxiety from the surgery are over, and you’re relaxing while the tranquilizers take over. You will be put in the waiting room for about 20 minutes for your corneas to bed down some more, and may fall asleep. Your eyes will be checked under the slit lamp microscope to verify that your flaps are properly bedded down, and then you’ll be sent on your way, but you will NOT be allowed to drive, so make sure you have someone with you.
You will have a dark pair of wraparound sunglasses, which you should use every time you go outside for the first week. You should use good sunglasses regularly afterwards, since exposure to UV has been suspected in causing haze in PRK patients, and LASIK is similar enough to PRK that you don’t want to take a chance. In addition, you’ll be minimizing your chances of having cataracts or retinal problems later in life, all of which apparently are increased by exposure to the sun’s UV light. You will also have plastic eye shields that you should tape over your eyes every night before going to sleep so that you don’t rub your eyes and accidentally dislodge your flaps before the epithelium regrows over the edges (there’s a 50nm-wide “gutter?around the edge of the flap at first, that the epithelium must fill in and grow over. Eventually, this gutter will form a scar—don’t worry; it’s too small to see with the naked eye and too small to show up in your visual field. You will never see it, and only people who look carefully at your eyes under a slit-lamp microscope will be able to find it.). The first 5 days are critical—you do not want to dislodge the flap! After that critical period, you’re not going to move the flap without surgical tools (NOT that you should try!)—loose talk about rubbing your eyes and coming away with your flaps in your hands is hokum (barring complications that delay re-growth of the epithelium). You will also have some steroid drops, some antibiotic drops (ofloxacin is best), some artificial tears (patients in Canada get this nifty tear gel instead), and possibly a non-steroidal anti-inflammatory drop. Use them all religiously, and follow instructions. You can use the artificial tears as often as you like—use them liberally. Make sure you wash your hands before doing anything at all with your eyes, so that the chance of infection is minimized. An infection under the flap can cause scarring that can blind you, so do not screw around here!
You will probably want to take a nap. Go right ahead—you heal the fastest while you sleep. Use your eye shields! When you wake up, you will already be able to see quite well, and it should get even better over the next few days as your corneal edema (swelling) goes away. You may experience a mild burning sensation after a few days. This is the severed nerve endings from the cutting of your corneal flap re-growing. Avoid the urge to rub your eyes—try to soothe them by using refrigerated artificial tears instead (the coolness feels good).
The day after surgery, you will return to the laser center to have your flaps checked under the microscope and to have an initial refraction. If everything is OK, you’ll be discharged to the care of your local O.D., whom you should see when they tell you to (usually 3 days post-op, then 1 week, then 2 weeks, then 1 month, then 3 months, then 6 months, then 1 year). Don’t blow these visits off. If any complications arise, such as epithelial ingrowth, you’ll want to get them resolved right away.
Vision isn’t perfect the first day after LASIK. There is some post-surgical edema that causes a bit of haze, especially at night, when you see some halos around lights and have reduced visual acuity. This clears up within three months.
For about three months, you may experience fluctuations in your acuity. You may see really well one day, and not so well the next. Be patient?because there’s no blood supply, the cornea heals slowly. It can take three to six months for vision to stabilize. Don’t even think about getting an enhancement until at least three months have passed!
You may be a little farsighted at first, to compensate for regression during healing (on the flip-side, if you were hyperopic before, you may be a little myopic at first). Over the next few months, this will normalize itself and you should end up either emmetropic (i.e., neither near nor far sighted) or slightly myopic. You don’t want to end up very far-sighted, or else you’ll need reading glasses earlier than you otherwise would as you age. If you end up slightly myopic, it will be a blessing when you turn 45, because you’ll still be able to read most things without reading glasses.
At the current time, the Federal Aviation Administration permits (yes, permits) recipients of RK, PRK, LASIK, epikeratophakia, and IOL to hold commercial pilot’s licenses following a satisfactory report from the pilot’s ophthalmologist that the results have stabilized (this could take from one to six months after surgery) and meet FAA medical criteria. For further reference, please refer to the FAA’s Aeromedical Certification Update of March, 1998, titled “RK and Laser Visual Acuity Procedures,?/A> by Dr. Warren Silberman, D.O., M.P.H. See also this note I received from an FAA employee.
A WORD OF WARNING: As documented in Jon Krakauer’s book, Into Thin Air, RK recipients will experience degradation of their vision at low atmospheric pressure. One climber, Dr. Beck Weathers, was effectively blind near the top of Mount Everest—his RK-treated corneas had so dramatically changed shape in the thin air that he could not focus on his feet (he was terribly farsighted at this point). He got lost in a sudden storm and spent a night in the open, exposed to wind chill of seventy degrees Fahrenheit below zero, and ended up losing one of his hands and all of the fingers of the other hand to frostbite. Hyperopic progression at altitude is a well-known problem with RK. If you get (or have had) RK, are flying at high altitude, and lose cabin pressure, you will be unable to read your instruments. If you’re a passenger who has had RK and the plane loses cabin pressure, you won’t be able to see the oxygen mask right in front of your face. This is yet another reason to avoid RK at all costs. Now that PRK and LASIK are available, there is no reason for anyone to ever elect to get RK.
(NOTE: I do not know if LASIK or PRK recipients will have the same problems as RK recipients at low atmospheric pressures. I don’t know that the question has ever been studied, and I would appreciate it if someone who does know would drop me a line.)
I have also recently been informed that refractive surgery is now allowed by the United States Armed Forces. However, it is NOT allowed for military pilots, and might not be allowed for divers and SpecOps personnel. If you fall into one of those categories, or if you want to, investigate this issue thoroughly.
Don’t think of having surgery and lying about it, either. In the case of RK, ICR (intrastromal corneal ring), and some ICLs (implantable contact lenses), the evidence will be visible to the naked eye during close inspection (as in, during your annual medical evaluation). In the case of PRK and LASIK, the evidence shows up quite clearly when a corneal topograph is made of the eye (the front of the cornea shows up as flatter for myopia patients, while the edges show up steeper for hyperopia patients). ICLs implanted behind the iris may be difficult to detect, but should show up rather dramatically when the iris is dilated for a routine retinal health examination. I’ll omit for now the discussion of increased cataract risks from this type of ICL.
That’s the Cliff’s Notes version. For more technical reading, follow the links below. (NOTE: I moved Dr. Friedman’s site to the bottom of the list of links. In my opinion, his continual extolling of the virtues of Dr. Galvis on sci.med.vision, without disclosing that Galvis pays him to set up groups to go get the surgery, is unethical. Furthermore, getting information from Friedman about Galvis’s statisics (and particularly complication rates) and treatment techniques is like pulling teeth. His website downplays the risks, almost to the point of completely failing to mention them. Finally, the informational video I received from Friedman makes little to no mention of the things that can go wrong, and is big on testimonials. The rest of the links are to articles from Ocular Surgery News, The Journal of Refractive Surgery, and archives from the American Medical Association’s publications website.
The first link is the “I know why all refractive surgeons wear glasses?web site, which contains a wealth of detailed information about what can go wrong in refractive surgery, as well as “quirks?that will be present in your vision even if you have an excellent result. I have a few issues with some of the content, and there’s little LASIK-specific information there (most of the information is relevant to PRK and much less so to LASIK), but on the whole, it is a very well-done and balanced web site. I cannot encourage you strongly enough to read through that site completely and carefully before you undergo LASIK or any other procedure. There are risks to refractive surgery, and, as I mentioned, there are some negatives even in a successful result (e.g., you may read 20/20 on the eye chart, but your night vision may be fraught with glare and halos, especially in the first few months post-op). The negatives may be lesser in frequency and severity with the more advanced treatments and hardware available outside the U.S. (the “I know why?web site doesn’t discuss foreign LASIK results—this is one of my issues with it), but I can’t say for certain, since everyone heals differently.
A few things are worth repetition and emphasis:
- Despite all the advertising hype, not everyone gets a 20/20 result. In fact, truth-in-advertising would require that laser vision advertisements advertise “reduced dependence upon glasses or contacts,?and would require that no mention of something like “throw away your glasses?be permitted at all (the FTC has cracked down on some of the more egregious advertising, but there’s still a lot of hype out there). Somewhat less than 60% of PRK patients in the VISX FDA study achieved 20/20 or better after one treatment. (The “I know why?web site will tell you why I believe the VISX numbers are more trustworthy than the Summit numbers.) The FDA numbers for LASIK aren’t in yet, but they are expected to be at least as good, if not slightly better (the final correction in LASIK is much more predictable than it is with PRK, so the initial correction can be made much more precisely). There is no guarantee that you’ll end up 20/20. There’s a very large chance (95%) that you’ll be 20/40 or better, but if you aren’t willing to tolerate the chance that you’ll be one of the 35% or so that end up between 20/20 and 20/40, don’t get the surgery.
- Even if you get 20/20 visual acuity, your vision still may not be perfect. LASIK is well-known for producing problems with night vision, including glare, halos, and a slight generalized blurriness when the lights go dim. Most of these problems go away almost completely within six months, but some people have permanent increases in night vision problems over preoperative levels, and almost everyone will notice some change for the worse, however minor. Night vision problems are subjective as well—what bugs the heck out of some people might not bother you at all, and vice-versa. These problems are reduced with larger ablation zones (6mm is really the minimum you should allow anyone to do), but there is a tradeoff: the larger the ablation zone, the deeper the ablation has to be to achieve the same correction. This leaves your cornea thinner than it might have been with a smaller ablation zone. Many surgeons believe 6mm is an ideal compromise, but patients needing lesser correction may be able to have their correction blended better with a larger ablation zone, alleviating a lot of these night vision problems. Note that no machine that is currently FDA-approved in the U.S. can make an ablation larger than 6mm. For larger ablations, you will have to get your surgery outside of the U.S. or at one of the few centers that is using an investigational laser such as the Nidek, Chiron 217, or Autonomous Technologies.
- Refractive surgery can introduce astigmatism where you did not have it before, and it can be “irregular?to boot. Most astigmatism is “regular,?meaning that is is symmetrical with respect to the meridians of your cornea (if you don’t understand, the “I know why?web page can explain it). Irregular astigmatism is asymmetrical and is harder to fix—none of the current-generation lasers in the U.S. can fix it, and until topo-link is perfected, none of the 3rd-generation lasers elsewhere in the world can, either. Furthermore, glasses and contacts can only approximate a correction to irregular astigmatism (RGP contact lenses can completely correct mild cases, but even they have their limitations.). With respect to LASIK, this problem is caused by a flap that was not properly smoothed out when it was laid back down on your eye, or by irregular flap healing. A skillful surgeon is less likely to introduce this problem, but there are no guarantees.
For what it is worth, my refractive surgeon does not wear glasses. :-)
Here are the links:
- “I Know Why Refractive Surgeons Wear Glasses?/A>. This page carefully details the potential risks of refractive surgery, including the negative aspects that go along with successful outcomes. If you read nothing else, read everything at this site carefully. This site provides the best informed consent I have yet seen. I disagree with some of the contents, and I am preparing a page that details my disagreements, but on the whole, this page is dead-on. The authors of this page have a friend who had a disastrous PRK outcome, and whose surgeon did NOT properly disclose the risks. . I don’t have many commercial links here, but this one is chock full of information, including realistic successful outcome expectations, hyperopic corrections,
- History and developments in the correction of vision
- OSN: LASIK is rising star in refractive arena
- OSN: LASIK called better than PRK for high myopes
- OSN International Edition: Patients are choosing LASIK over PRK
- PCON: LASIK, PRK go eye-to-eye in Saudi clinical trial
- OSN: Who should decide to perform LASIK or not
- JRS: Regulatory Considerations Regarding the Use of the Excimer Laser for LASIK
- PCON: Approach LASIK with caution, education
- OSN: LASIK, the future of refractive surgery
- OSN: Bilateral simultaneous LASIK is safe and effective
- OSN International Edition: LASIK shield protects hinge during astigmatic treatment
- OSN International Edition: Avoiding LASIK complications takes patience
- OSN: Patient's third enhancement procedure
- OSN: American team uses multizone LASIK to treat high myopia
- OSN International Edition: Restoring stretch to Bowman’s membrane reduces late-onset islands following LASIK
- OSN: Post-LASIK antibiotics must achieve deep penetration
- OSN: Superior hinge LASIK with new microkeratome improves safety
- OSN: Just how secure is the flap with LASIK?
- JRS: Histopathological Comparison of Photorefractive Keratectomy and Laser In Situ Keratomileusis in Rabbits
- Medical News & Perspectives - November 15, 1995 (c) AMA 1995
- Chiron Vision, makers of the Technolas Keracor 117 and 217 excimer lasers and the Chiron Automated Microkeratome
- Sci.med.vision newsgroup FAQ
- EyeWorld, a trade publication
- Hands on: Thirteen steps to a perfect LASIK for the beginning surgeon—Feature Article
- Refractive Tool Time: LASIK surgeons develop eye-opening speculum designs—Feature Article
- Brian’s Eye Tests—tests for abnormal/diseased eye function
- Physical and spatial aspects of night vision
- Friedman’s LASIK Page
This page ?1997 and 1998 by Chris BeHanna. Copyrights of pages linked in above are owned by their respective copyright holders.
I have received no money for putting together this page. It is strictly for your information and education. I am not a medical professional; if you need medical advice, consult an opthalmologist. No warranties of any kind are offered for the information on this page.
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