History of LASIK
LASER VISION CORRECTION
Laser-Assisted In-Situ1 Keratomileusis2 (LASIK)
A Non-Technical Review of a Technological
Breakthrough with a Fascinating History
Laser Vision Correction: A Non-Technical Review
Similar to using crutches to walk after breaking a leg, approximately half of the population uses eyeglasses or contact lenses as a crutch to see. But, if you broke your leg, can you imagine how you would feel if your doctor told you that you would have to walk with crutches for the rest of your life? Well, for many years as a practicing ophthalmologist3 , I told my patients that very same thing"I know you can't see well without your glasses, but, there's nothing I can do - here are your glasses (crutches)". Prior to laser vision correction, there weren't many alternatives around for people who needed to wear glasses or contact lenses.
Those of us who don't wear glasses or contacts can't fully understand the miracle of LASIK surgery. People with good unaided vision take for granted the simple, daily tasks that are extremely cumbersome for eyeglass and contact lens wearers. To put things into perspective, try to imagine not being able to see your clock every time you wake up from sleep to make sure you didn't miss hearing your alarm. For men, ever tried lathering up and shaving your face with glasses on? Or, how would you feel if you had a contact lens dried onto your eye while snow skiing or driving down the highway on a motorcycle at 70 mph. These are just a few examples, the real hassles for eyeglass and contact lens wearers are much more numerous making their lives significantly more complicated than ours. Much of the free time we take for granted, others are busy searching for lost glasses or contacts, sterilizing lenses, buying cleaning solutions, following up with eye doctors, etc. just so they can be prepared to take on the rest of the daily hassles in life.
In 1985, as a resident in ophthalmology, just like all other ophthalmology residents, I was trained to treat eye disorders such as cataracts4 and glaucoma5 . But, what quickly became apparent to me was that we were not treating the most prevalent eye disorders of all - nearsightedness, farsightedness, and astigmatism6 (refractive errors7 ) - these were the disorders the majority of my patients complained most about. Weren't there any more permanent methods available to correct refractive errors? I knew about radial keratotomy8 (RK), but, RK was not for everyone and only worked well for people with low degrees of nearsightedness. Then, I reviewed an article written in the December, 1983 issue of the American Journal of Ophthalmology by Steve Trokel, MD describing a new excimer laser 9 that may someday be used to reshape the window to the eye (the cornea10 ) to treat refractive errors. This was my first introduction to the idea of laser refractive surgery. Little did I know at the time that by1988, I would be working directly with Steve and others to refine the laser that would perform the first human laser vision correction procedure in the world!
Sequence of Events:
During the late 1970's and early 1980's, the excimer laser was used primarily by the computer industry to etch computer chips. The concept of using the excimer laser for an entirely different purpose, to treat biological tissue, was realized by two physicists independently, but nearly simultaneously.
During the late 1970's, Dr. John Taboada was a physicist at Brooks Air Force Base in San Antonio. He was assigned by the military to research the safety and biological effects of using a new kind of laser called the excimer which generates invisible ultraviolet light in high energy pulses (the military was considering the use of ultraviolet light to communicate between satellites and submarines). In 1981, Dr. Taboada reported that the excimer laser created "craters" in experimental rabbit corneas. The craters took on the exact dimension and shape of the laser beam without harming the adjacent tissue. It is a matter of considerable controversy whether Dr. Taboada, at that time, realized the significance of his discovery related to laser vision correction (at issue, $80 million in past royalties).
Nearly at the same time, another physicist at IBM Research Center in New York, Dr. R. Srinivasan, discovered the phenomenon of Ablative Photodecomposition11 (APD) using the excimer laser in 1980-81. His first report was entitled"Far- ultraviolet Laser Ablation12 of Atherosclerotic Lesions13 ". A second report entitled"Far-UV14 Photoetching of Organic material" was published in "Laser Focus" in May of 1983. To demonstrate APD in the most dramatic way, Srinivasan produced an electron micrograph, of a highly magnified single human hair, in which precise cuts were etched by the excimer laser. Since people could relate to the heat sensitivity of hair, this image had a strong impact and was reproduced widely around the world. Each pulse from the laser removed a constant amount of tissue without any thermal damage to adjacent tissue. Therefore, by simply counting the number of laser pulses, one could determine the amount of tissue removed within sub-micron accuracy. IBM was issued a patent in 1985 which broadly covered the use of the excimer on biological tissues but, crucially, didn't mention eyes.
In 1982, Dr. Steve Trokel, an ophthalmologist who worked nearby IBM at Columbia Presbyterian Hospital was working with a different type of laser called the Nd:YAG laser. This laser remains in use today in cataract surgery. Hearing that Dr. Taboada had worked on the Nd:YAG laser, Trokel asked Taboada to write a chapter for a book. In March of 1983, Taboada met with Trokel and told Trokel about his excimer laser experiments on rabbit eyes. After learning about Taboada's experiments, Trokel became interested in Srinivasan's work at IBM. Trokel brought with him the Taboada articles and some veal eyes to test the effects of the excimer laser beam on the cornea. Similar to Taboada's work, the experiment revealed the ability to make precise incisions without harming adjacent tissue. Trokel was "awe-struck" by the results and accurately foresaw that this would be the next great laser in ophthalmology. Within days, he flew to Europe to meet with the manufacturers of the IBM excimer laser to purchase his own laser.
Trokel was quick to file his own patent relating to refractive surgery and began refining his industrial laser for ophthalmic use. He formed a team of physicists, Charles Munnerlyn and Terry Clapham, to help him develop & commercialize this new concept. He consulted with two ophthalmologists Herb Kaufman, MD, Chairman of the LSU Eye Center in New Orleans and Marguerite McDonald, MD, also from LSU, who both earned leading international reputations in refractive surgery.
In 1987, while presenting a paper at the Association for Research in Vision and Ophthalmology, I met Herb Kaufman who asked me"what would you think about a laser that in less than a minute could obviate the need for glasses or contacts forever?" Trying to cover-up the anxiety I felt after just speaking in front of hundreds of people and standing in front of the most respected ophthalmologist in the world, probably one of the simplest minded replies of all times slipped out of my mouth,"Wowwww !" Fortunately, I must have made a good impression upon Dr. Kaufman during my paper presentation, and just a few months later, he accepted me into his cornea and refractive surgery fellowship at the LSU Eye Center in New Orleans, LA; one of the most prestigious fellowships in the world.
In 1988, I began my refractive surgery fellowship at the LSU Eye Center in New Orleans, the same year Trokel assigned his patent rights to a new company called VISX, founded by Charles Munnerlyn. Also, this was the year VISX began testing its first prototype on humans at LSU. The very first patient to receive excimer laser surgery was a woman with uveal melanoma (a cancerous tumor that requires complete removal of the eye). Therefore, she voluntarily provided the opportunity for us to test the laser since there was little potential of doing additional harm. A week after the procedure, her eye was removed and studied histopathologically15 for any evidence of laser injury to the internal structures. Similar to Trokel's and Taboada's early experiments in animal eyes, no damage occurred to adjacent or internal tissues of the eye. Thus, the Food and Drug Administration (FDA) allowed us to proceed with Phase I of the VISX investigational device exemption (IDE) on 10 blind eyes and then Phase II on 10 partially sighted eyes.
Oddly enough, unbeknownst to the non-suspecting ophthalmology resident who examined her preoperatively, one of the blind patients was hysterically blind. In other words, there was no physiologic reason for her blindness. On her post- operative examination, after driving a car to the clinic, she pronounced she could see and proceeded to read 20/20 off of the eye chart. Needless to say there were a lot of wide open jaws in the clinic that day. Not only did the laser relieve this patient's subconscious effort to suppress vision, but in addition, she was the first to experience the miracle of laser vision correction. Fortunately, the laser vision treatment corresponded to the high degree of her pre- existing nearsightedness.
During all of the animal experiments and clinical trials from 1985 to 1993, all of the procedures were performed as PRK16 (photorefractive keratectomy). For PRK, the laser is aimed directly at the surface of the cornea removing an area of tissue approximately 6 mm in diameter. One of my professors at LSU, Gholam Peyman, MD thought that this resulted in too much damage to the surface of the cornea leading to delayed healing, increased pain, and increased risk for scarring and infection. I also felt that there must be factors released by the healing corneal surface (the epithelium) which caused the underlying cornea (the stroma17 ) to scar. Therefore, Peyman and I began performing experiments in 1988 using a solid state erbium laser under a thin flap of corneal tissue which is how LASIK is performed today. By making a flap, the laser treatment is performed on the inside of the cornea allowing the surface of the eye to remain relatively undisturbed, therefore, there is virtually no pain and healing occurs within hours instead of days to weeks. In 1991, we published the first paper describing the experimental LASIK technique on primates. † At that time, the procedure was very difficult since I had to make the flap manually, thus, I hardly suspected that other surgeons would rapidly master and perform this technique. However, after Luis Ruiz, MD perfected the automated microkeratome18 to make a corneal flap, LASIK has now become the most commonly performed refractive procedure in the world!
In 1989, we began the PRK studies on sighted eyes at LSU. As mentioned above, LASIK surgery was not even considered for the reason of increased surgical difficulty. The PRK results were exceptional for people with nearsightedness of 6.00 diopters19 or less. Above that number, PRK typically resulted in corneal scarring (today, with LASIK, we can successfully treat up to 12.00 diopters of nearsightedness). Encouraged by these early results, the FDA permitted VISX to open 10 additional experimental sites in the US where 75 patients could be treated at each site. In 1990, upon completion of my fellowship, I moved to St. Louis where I became one of the 10 VISX excimer laser principal investigators. I completed my portion of the study in 1992 and it wasn't until 1995 that the FDA approved PRK for the treatment of nearsightedness.
From 1992 to 1995, I traveled to numerous countries training other surgeons in laser vision correction. Since other countries were not restricted by an entity similar to the FDA, PRK started to became popular with surgeons in South America, Europe, and Canada. However, it still did not seem to become too popular with patients. I had several patients who had undergone RK on one eye and then later, decided to have PRK on the other eye. I was somewhat astonished to learn that most of these patients preferred their RK eye! They said the pain was less, and their vision returned faster. I quickly realized that Dr. Peyman and I were right back in 1989, LASIK would solve these problems.
Therefore, in 1994, I flew to meet with Luis Ruiz who demonstrated to me the use of his new automated microkeratome. He was already performing hundreds of LASIK procedures each month and the results were astonishing. I quickly mastered his technique and became one of early US surgeons to adopt the procedure and begin performing LASIK abroad (we still did not have FDA approval in the US for the excimer laser even for PRK). In China, where more than 70% of the population is nearsighted, I established 4 LASIK clinics where several hundred procedures are performed at each clinic every month.
Today, even though the FDA has only approved the VISX, Summit, Nidek, and Autonomous lasers for PRK, the vast majority of laser surgeons are performing LASIK since the patient benefits of LASIK significantly outweigh the benefits of PRK (as long as the surgeon is using an FDA approved laser, or a laser for which an IDE was filed, this is permitted). Most surgeons reserve PRK for specific conditions where LASIK would be inappropriate.
For additional information, please contact Dr. Craig F. Beyer at Beyer Laser Center in Boulder, Colorado: 303-499-2020
Footnote Definitions:
- In-Situ: a Latin term meaning"in place" or not removed. The eye is not removed for this surgery.
- Keratomileusis: carving of the cornea to reshape it.
- Ophthalmologist: a medical doctor specializing in the diagnosis and medical or surgical treatment of visual disorders and eye disease.
- Cataracts: Opacity(see opacity)of the lens or capsule of the eye, causing impairment of vision or blindness. Source: The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
- Opacity: The quality of being impenetrable by light.
- Glaucoma: a disease of the eye marked by increased pressure within the eyeball that can result in damage to the optic disk and gradual loss of vision
Source: Merriam-Webster's Medical Dictionary, © 2002 Merriam-Webster, Inc.
- Astigmatism: a distortion of the image on the retina caused by irregularities in the cornea or lens.
- Refractive errors: imperfections in the focusing power of the eye.
- Radial keratotomy (RK): Surgical modification of corneal curvature to correct myopia (nearsightedness) by making symmetrical incisions into but not through the cornea.
Source: The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
- Excimer laser: an ultraviolet laser used in refractive surgery to remove corneal tissue.
- Cornea: the clear, front part of the eye. The cornea is the first part of the eye that bends (or refracts) the light and provides most of the focusing power.
- Ablative Photodecomposition: Ablate in surgery, is to remove. So Ablative Photodecomposition would be the removal of corneal tissue in this case by the use of a laser.
- Ablation: Ablate, in surgery means"to remove." So, ablation is the fact or state of being removed.
- Atherosclerotic Lesions: "Lesions" are a localized pathological changes in a bodily organ or tissue. "Pathological" means relating to or caused by disease. And"Atherosclerosis" is the most common form of arterial degenerative disease, in which fatty material is deposited in the inner wall of your arteries, narrowing the arteries and eventually restricting the blood flow.
Therefore,"Atherosclerotic Lesions" are those changes in the arteries that are or would be considered a disease and affect the health of an individual. Laser Vision Correction: A Non-Technical Review
Source: The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2000 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
- UV: Ultraviolet light or the ultraviolet part of the spectrum. This is the light that is just beyond the violet in the visible spectrum.
Source: The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2000 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
- Histopathologically: The study of the microscopic anatomical changes in diseased tissue.
Source: The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2000 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
- PRK: the acronym for photorefractive keratectomy (see keratectomy) which is a procedure involving the removal of the surface layer of the cornea by gentle scraping and use of a computer-controlled excimer laser to reshape the stroma. (See Stroma)
Source: http://www.fda.gov/cdrh/LASIK/glossary.htm
- Keratectomy: the surgical removal of corneal tissue.
- Stroma: the middle, thickest layer of tissue in the cornea.
- Microkeratome: a surgical device that is affixed to the eye by use of a vacuum ring. When secured, a very sharp blade cuts a layer of the cornea at a predetermined depth.
- Diopter: the measurement of refractive error. (See Refractive Errors) A negative diopter value signifies an eye with myopia (nearsightedness) and positive diopter value signifies an eye with hyperopia (farsightedness).
