The aim of refractive surgery is to reduce the patient's dependence on vision correction prosthesis: glasses or contact lenses. While there are numerous forms of the surgery, the physical result is the same. The cornea is reshaped to allow images to focus accurately on the retina.
To do this, the outermost layer of the cornea called the epithelial layer, is removed temporarily exposing the softer layers underneath. In LASIK this is done by slicing off a layer with a microkerotome (very sharp razor), in LASEK a chemical agent (denatured alcohol) causes the layer to "blister" off. An ultraviolet excimer laser is used to ablate the lower layers by several microns (millionths of a meter). The epithelial layer is then replaced. For the most popular procedures, LASIK and LASEK, entire procedure takes roughly 8 minutes per eye for LASIK, and 12 minutes per eye for LASEK.
In many cases, the same surgeon can do either procedure.
While the patient's vision is corrected from the moment the epithelial layer is replaced, things are foggy for the first day or two while the layer reseats. After that, vision settles to some nominal level close to perfect correction.
There is no blood flow to the cornea so the healing is slow and can take up to a full year to heal completely. Until that time, the epithelial flap can be lifted manually with special tools if the vision needs "tweaking".
There are numerous sites with data on the internet on these procedures which are performed these days in an almost "fast-food" atmosphere, and I will not attempt to reproduce the technicalities of the process. However, I have had the LASIK process performed on my own eyes, and I have first-hand experience with an individual who has had LASEK, and in this wu I will relate the data gathered from those experiences.
As a 42-year old male I suffered from what had been termed "severe myopia". My vision had been correctable only by +8 diopters in my left eye, +7.5 in my right eye. My vision had been stable for over 20 years. I had no astigmatisms. It was clear I was going to begin to need reading glasses. I had worn contact lenses for about 10 years. My pupil size is 8mm.
My friend is a 32-year old female suffering from a myopia less severe than mine. She wanted to reduce her dependence on glasses and contacts for cosmetic reasons. Her pupils are slightly larger than 7mm, but her corneas were deemed too thin for LASIK. Her best alternative for laser correction was LASEK (or much more involved and less accurate manual processes like PRK).
The Lead In:
This dependence on glasses disturbed me. Without my glasses I was so nearsighted that I had a hard time identifing my feet when looking down in a room at dusk. Certainly, if I dropped my glasses, or my glasses fell off the night stand in the middle of the night, it could take me 1/2 an hour to locate them if I was in a strange place, such as a hotel. As I was about to embark on an expedition to Antarctica, I realized that if my wire-frame glasses fell off in the snow my ability to locate them was nearly nil (as I had discovered on skiing trips) and in Antarctica that problem could be fatal. Contact lenses seemed out of the question. Having to take out and clean lenses every day seemed impractical on an expedition. Because of my large, 8mm diameter pupils, I continuously needed "special" lenses and there were no disposable lenses made in my size. Losing a lens on the ice would drive me back to glasses, anyway. In addition, the idea of switching glasses or getting bifocals to read made me feel helpless. There was only a small window about 6" in front of my nose in which I could see anything clearly without visual prostheses.
One limiting factor for laser correction machines is the surface area over which they are effective. Until 2001, there were no machines in the San Francisco bay area that could accurately ablate over a pupil diameter greater than 7mm. In 2001, newer machines became available that could operate over an 8mm+ circle, and so laser correction became an option for me.
The process I was introduced to required an optometrist and a Laser Surgeon to work as a team. Doctors who use this team approach claim a superior safety record to the laser surgeon who serves both functions. Surgeons who do both claim the eye-team approach has inherent "dangers".
Having read as much as I could, I couldn't figure out whom to believe. I had been seeing the same optometrist for 15 years and he had some tens of patients he gave as references. I called a couple, and after receiving the "scoop", decided to stick with the "team" approach, strictly to stay with my doc, whom I trusted. Naturally, I didn't expect he'd give me a bad reference, but the internet is replete with LASIK horror stories (read: www.lasereyes.com) terrible enough to frighten anyone out of the process, and I felt I had all the warning I needed.
My friend used the same surgeon I used, but a different optometrist.
The Pre-Op Screenings:
My optometrist took a series of measurements in his office. These were mostly related to my current vision, cornea size, and the condition of my retinas. He gave me the preliminary warnings about the procedure. He said that because of my pupil size it would be impossible to correct my vision without introducing artifacts. The process would reshape my cornea by flattening it. A flattened cornea would allow multiple sideways light paths through my pupil that didn't exist in my natural eye. After surgery, the edge of my pupil would be too close to the edge of the corrected region and refraction would occur.
Thus, at night, I was liable to see blooming, starbursts, or even multiple images in point sources of light. There would be no ill effects during the day, nor would I have any problems with computer or TV screens. I would most certainly, absolutely, require reading glasses to read anything, though my distance vision would be good.
The process could introduce astigmatism, where I had none.
Finally, because my vision was so bad, and so much material had to be ablated to correct my vision, the chances of my coming out a perfect 20/20 were slim. Thus, they would tend to adjust their parameters so as to undercorrect my vision rather than overcorrect--meaning they would remove less cornea. This way, if I felt like going back for a "tune-up", they would be making very minor changes that could be done very accurately. Tune-ups could be done with minimal difficulty up to a year after my initial surgery for zero cost. After that time, I needed to consider the surgery starting from scratch.
He told me I'd lose night contrast, and would suffer from night-myopia, mostly because of my age. These would reduce my night vision and I'd probably need some glasses that would provide a minor correction for driving at night.
He didn't go into all of the potential complications of the surgery, but said the chances of complete blindness were so close to zero that in over 20,000 procedures performed by the surgical team I would see, no one had gone blind or had their vision severely damaged--though it had happened to others, and I could read about those cases if I wanted. The most common cause of severe problems was post-op infection. Procedures were improved, and the combination of chemicals and antibiotics used had all but eliminated those events. Yet, statistics are not certainty.
Though he made it seem my chances were greater of being struck by lightning than having a complication from the surgery. At no point did he urge me not to proceed. He'd seen people with worse vision complete the process successfully, which made me wonder what he told those people. Were they just fearless with their eyesight?
He scheduled me for a consultation with the surgeon. I expected to need several weeks lead-time, but in fact, I got in the following day. The train was rolling.
The pre-op with the surgeon took about 20 minutes. My eyesight was measured again with more accurate machines in the surgeon's office, using the initial figures provided by my optometrist. Then they did a few other interesting tests. One involved a machine that mapped the undulations in the surface of my cornea and my cornea size to within a micron. The measurement was completely optical and thus painless.
Then they measured the thickness of my cornea. This involved numbing my eyeballs, and while I sat in the examination chair, I allowed a technician to poke me in the eye with a probe. Though it did not hurt, it was an amazingly disturbing experience.
The technician held my eyelids open, and then I saw the point of the probe approach my eye. Though I could not feel the contact, I could see my vision distorted when the probe pressed against my eyeball as if looking through a glass of water. The technical made about 10 pokes in each eye, directly into my visual area. By the time we got to the last poke I was quite comfortable with sharp things being shoved into my eyes and wondered if that skill was valuable in any other pursuit.
The final test was performed by the surgeon himself. He darkened the room and then took pictures of my eyes and face using a Sony video handicam in complete darkeness. He was using the infrared signature, but I never found out what it was for.
After making some calculations, he told me the same things about risks and side-effects my optometrist had said. He gave me two videos, and asked me if I wanted to go through with it.
I said yes. It was Thursday. My surgery was scheduled for the following Monday.
The cost of surgically altering my vision was to be $3500 US. This covered everything, including follow-up visits for a year and "tune-ups" if I needed/desired them. These days in the U.S. surgeons offer to perform the procedure for as little as $200 per eyeball. So, what did I get for my additional $3100?
As far as I can tell, I paid for the reputation of the surgeon. I paid to have my eyes blasted by the super-quality VISX machine, rather than older models. (At the time I went, the Bausch and Lomb laser had specs even better than the VISX machine, but I couldn't find anyone in my area who had one.) As dubious a return on investment as that may be, I had no problems paying the ante. I felt, as I'm sure everyone else in that packed waiting room did, that you get what you pay for, and when playing with the only eyesight you'll ever have, perhaps paying more was better than going with the lowest bidder.
However--other than the fact I went with Dr. LASER EYEBALL himself, there was no difference between the machine or the procedure than had I gone elsewhere.
The first tape was roughly ten minutes long. It was a visual of a complete surgery taken from the viewpoint of the excimer laser machine. A single eyeball filled the screen.
First, antibiotic and anesthetic eyedrops were applied. After several seconds, plastic eyelid holders--similar to the type used on Alex in "A Clockwork Orange" -- were put into place, preventing the patient from blinking.
Next, a ring-shaped suction device was placed on the eye. The microkerotome slid into a groove in the apparatus, and then of it's own power (it appeared to be electric, but may have been air powered) it ran across the ring slicing a thin, clear, gelatanous layer off the front surface of the eye.
Fascination replaced my horrible nausea. At no time did the surgeon's hand leave the patient's face. I had been led to believe the process was entirely automated, but this was clearly not the case. He adjusted the ring. Made tiny adjustments on the microkerotome. When he removed the ring and the microkerotome, he used delicate tools to keep the flap of cornea moved aside and the eyeball insides clean. And now I realized that if he slipped or ever said, "oops" very bad things could happen.
He moved his hands away when the laser fired its invisible beam. I could see absolutely nothing happening except the reflection of a red LED shining in the pupil.
After several seconds, the surgeon replaced the flap with his delicate tools and then massaged it into place, being extremely careful to smooth out any wrinkles and to keep the area irrigated.
Eight minutes after it started, the surgery was over.
The second tape consisted of a thirty-minute lecture by the surgeon. He went through an agonizing description of the surgery and the complications that could occur at each step should he make a mistake. He described the possibility of infection and showed pictures of the results.
By the end of this tape, I was convinced glasses were better than slicing my two-and-only god-given eyeballs, however defective they were.
But some 50,000 people per year go through the surgery with no ill effects. And this statistical realization gave me the courage to get in the car on Monday morning.
For obvious reasons, you need to be driven to laser eye surgery. Some places include a limo service in the price. Mine did not. A friend drove me.
At the front desk I was given a complimentary bag of goodies. This included ultra-sterile saline solution. A prescription for eyeball anti-inflammatory agents, a small bottle of eyeball antibiotics, written instructions, strange clear goggles, and those big black wraparound sunglasses people only wear when they're over 70-years old.
All this came in a handy carrying bag that proclaimed, "Get LASIK".
I sat down in a chair in the crowded waiting room. They said people would be called in every 15 minutes or so. I had been advised to arrive 1/2 hour early for my appointment, but as soon as I sat down a nurse came and dropped anesthetics in my eyes. She took away my glasses, explaining I would not need them anymore, leaving me completely blind and as helpless as a goldfish who's jumped out of his bowl.
After two minutes, I was called into a small room and asked if I wanted a "complimentary valium" to which I replied, "Better living through chemistry," and downed the pill. They put one of those blue surgical caps on my head.
Fifteen seconds after I took the valium the door opened to the operating room and I was called in. Clearly, I was not going to feel the effects of the sedative during the surgery. They led me into the room, which I could not see except as a bunch of blotches of color--my normal vision.
They helped me get into a chair that instantly reclined so that I was laying flat.
Without any warning or fanfare, the surgery began.
More drops were put in my eye. A large device swung over my face and I could see a blinking red light. I was advised to stare at the light and as I did the machine adjusted itself (or the surgeon moved it) so that it was directly over my pupil.
He put the plastic eyelid holders on. There was no sensation. I could not close my eye, but I didn't care. I was pretty nervous at this point.
He put the suction ring on my eye. It simply felt tight, kind of strange because I usually don't have my eyeball squeezed, but it wasn't unpleasant. Then he inserted the microkerotome, and I heard it moving. It sprayed a bit of cool mist as it went. I knew it was cutting, but could feel absolutely nothing. The only perception I had was of a curtain covering my eye until everything went black.
And the surgeon said, "Everything should be black, now," and I agreed it was.
Then he removed the microkerotome and I could see again, though as badly as ever. I could see something that looked like a very small brush going across my eye, but felt nothing. After a few seconds he said, "Ok, stare at the light."
His hands were on my eye, head, or face, the entire time. I stared at the light and perceived absolutely nothing was happening.
Then I could smell burned hamburger. Yes, it was my eyeball being vaporized, but I could see or feel absolutely nothing but the red light flashing in front of me and the surgeon's hand resting gently on my cheek.
He counted down the seconds till the machine was done. The laser ablation lasted 40 seconds for me, which he said was a very long time.
After 40 seconds he squirted cool, soothing things into my eye and I could see him brushing across my vision. He brushed and brushed, moved things around like an artist smearing paint, and when he was satisfied he proclaimed, "Ok, all done," and moved the machine to my other eye.
The amount of time it took you to read those paragraphs describing the surgery is about the amount of time I perceived as required for the actual surgery.
The second eye experienced the same thing. Squeezing, blocking vision, burning hamburger, brushing, done.
When he swung the device away from my face, the chair moved to a sitting position.
The doc asked me what time it was, and for the first time since I entered the room I realized there was an analog clock on the wall. I could now see it, and although it seemed the room was filled with smoke (from burning eyeballs, no doubt) I could tell it was 10:32.
I said something stupid, like, "Hey, I can see."
And the doc said, "That's what we're here for."
The assistant doc put me in a standard optometrist's chair and took some measurements of how well corrected my vision seemed to be. He looked into my eyes with a microscope and checked out how well seated the epithelial layer was. After about 5 minutes of careful viewing (much longer than my optometrist would have taken), he taped two circles of clear plastic over my eyes and gave me some instructions.
Under no circumstances was I to touch my eyes for a whole day. I was not to bathe or shower or get anything, even water, in my eyes. I should try to keep my eyes closed for 24 hours. For the next week, when going to bed, I should tape the clear plastic lenses to my head to keep myself from rubbing my eyes in my sleep, or accidentally touching a sheet or pillow case to my eye. There was a schedule for the eyedrops: antibiotics and anti-inflammatories and I was not to miss it.
Followup appointments were scheduled. I'd go to see my optometrist the next day, then at regular intervals for six months while my vision stabilized.
Then he gave me a video tape. Yes, I have a video of my eye surgery. I show it to all my friends.
Then he let me into the waiting room. I sat in a chair with my eyes closed. And now the valium kicked in, and I began to float in relaxed wonderland.
My friend came by to pick me up. Instantly I stood up and proclaimed, "I can see!" and in true Monty Python fashion, proceeded to bark my shins against the coffee table and nearly fell to my knees.
The staff was happy to get rid of me, as I am told my antics caused some consternation among those awaiting their turn under the eye fryer.
The Next Few Days
The pill they gave me was something very strong. As soon as I got home I fell unconscious for nearly 8 hours. When I awoke, it was night and I went to bed.
The next morning I tore the plastic goggles from my head, and miracle of miracles, I could see "perfectly" well. Well, I thought I could, because compared to what I was used to seeing anything was remarkable.
I immediately went out and bought a pair of way-cool Maui Jim sunglasses and went to the optometrist who proclaimed me overcorrected in one eye, and slightly undercorrected in the other.
I didn't care. I was seeing without glasses or contacts. I was thrilled.
That night I saw the artifacts I'd been warned about. Every street light seemed to have four or five faint baby brothers. My night vision had become terrible. I was practically blind by the time dusk came.
I still didn't care. I was practically blind at times with my new laser-fried eyeballs, but I was actually blind with my regular pre-fried eyeballs.
As time went by, my vision changed. At first, almost daily, and then it settled out. As I write this, 13 months after my surgery, my vision is roughly 20:20 in my left eye, and something like 20:35 in the other. The interesting thing about this arrangement is that I can see distances with one eye, and close objects with the other. Thus I don't need reading glasses, which I had been guaranteed to need.
A slight astigmatism was introduced in each eye, where before I had none. On the other hand, I don't notice it, as being able to see at all is still remarkable to me.
In general, where I'd lived most of my waking hours adorned with glasses or contact lenses, I now wear no glasses except sunglasses. I do have glasses that correct my minor astigmatism and correct my right eye to 20:20. I wear these at night (sometimes) when I drive as they help my night vision, but truth is, I forget to bring them most of the time. When I do wear them, they almost completely remove the artifacts, which are trivial to endure compared to the total night blindness I had as a myopic individual.
I can see how people who rely on the precision of their vision to make a living would have a hard time adjusting to the changes in vision I experienced. Walking around without glasses, I still see a blurriness caused by the astigmatism. And one of my eyes is better adapted to distance and the other to close objects, so at any time one of my eyes is unfocused while the other works, and this takes some getting used to. Someone absolutely fastidious would go nuts with the artifacts I experience.
To me, someone who's worn glasses for 36 of his 43 years, the vision correction is nothing short of a miracle of technology. All of engineering involves tradeoffs, and the small tradeoffs I've made to be able to survive without visual prosthesis validate my decision, as far as I'm concerned. However, I can understand how someone with their heart set on absolutely PERFECT vision would be gravely disappointed with the results. This is not something to be taken lightly. And I would say the most important parameter of whether or not one decides to take laser surgery is how important not needing glasses is to them if replaced by slightly distorted, but prosthesis-free, vision.
My Friend with LASEK (vs. LASIK)
The difference between my surgery and my friend's is her epithelial layer was burned off with chemicals rather than sliced with a blade.
There are trade-offs to this process, too. Having your epithelial layer burned off by chemicals is dramatically less likely to introduce astigmatisms. In addition, because there is no "cut", there is no artifical interface created in the cornea. This reduces and even eliminates a lot of the multi-image and starburst artifacts (with LASIK these decrease with time, but always remain to some extent).
The trade-off is pain and recovery. No matter what the ads say, LASEK hurts like hell, and it hurts for a couple of days. There's no getting around the fact you've been given chemical burns on your eyeballs with denatured alcohol. (The epithelium removal process is manual. I'm not sure if this is a plus or a minus, but it's a difference.) To make matters worse, anesthetics reduce the efficacy of the antibiotics used to combat infection. So, once the topical drops wear off, you have to endure the pain or risk infection, and I have witnessed the pain to be quite extreme.
Despite a strong pain tolerance, my friend wound up eating vicodin every four hours, and even then I had to drive her to the optometrist on two occasions on an emergency basis to do something for the excruciating pain. This went on for two days, during which she was unable to function. After that, the pain subsided to the point it was bearable. After a week, she was fine.
However--there is no doubt that the results of her laser surgery are more precise than mine. No astigmatisms were introduced. She says she does not see multi-images on point sources at night, despite having pupils almost as large as mine.
I remember experiencing only a very short bout of discomfort with my LASIK surgery. But I was knocked unconscious by the pill they gave me, so couldn't begin to judge only to say that if there was pain it didn't last more than a couple of hours. I was functional within 24 hours.
I did ask the doc before my surgery if LASEK surgery would be better for me than LASIK, and he assured me my results would be virtually similar with less pain. Though it's clear it's to his advantage to push patients toward LASIK, as the procedure is simpler and the immediate after effects are less likely to result in a phone call to his office. Still--I am not unhappy with my results.
What to do with your old glasses:
You have no need for your old glasses anymore. They're for some other eyes than the ones you now have.
I donated mine to my optometrist. He does work for "Doctors Without Borders". My glasses now adorn the face of an a native Peruvian Indian high in the Andes.