A phalanx of high-tech products provide the ophthalmologist with one of the most advanced toolkits of any medical practitioner. Lasers, corneal mapping systems, and foldable silicone lenses enable ophthalmologists to repair the eye with non-invasive and minimally invasive techniques—often under computer control.
Ophthalmology has benefited more than any other medical specialty from the laser. The same light waves that enable the sense of sight can also be used to treat diseases of the eyes and correct vision. It’s as if the ear could be repaired or improved with carefully measured sounds.
Today, we can repair or even replace parts of the eye. Once we learn how to deliver images directly to the brain, as we almost surely will, then it will be possible to replace the eye entirely.
The history of vision correction surgery is a remarkable saga. It began in the now-defunct Soviet Union. Svyatoslav Fyodorov overcame his father’s denunciation and imprisonment, an accident in which he lost a leg, and massive Soviet bureaucracy to develop a revolutionary technique called radial keratotomy (RK). When Fyodorov’s daring method landed in the U.S., it evolved into today’s popular LASIK vision correction surgery.
In 1973, Fyodorov encountered a patient whose vision (at least in one eye) was corrected by a punch. Fyodorov examined the boy and found a small curvilinear incision outside the visual axis. He confirmed that the boy’s myopia was reduced by three diopters. Fyodorov exclaimed “If a fist can do this, so can I. After all, I am an eye surgeon.”
Once Fyodorov perfected his technique (involving up to 16 straight-line incisions arranged about the center of the cornea like spokes of a wheel), he found he could treat individuals with visual impairment in assembly-line fashion, employing multiple technicians, each assigned to perform a specific step. He established clinics all across Russia. By 1990, the clinics were treating more than 200,000 patients per year.
Fyodorov’s luck ran out when he died in a helicopter crash in 2000. Fortunately, by then his technique had spread beyond Russia. In 1976, Dr. Leo D. Bores of Detroit, Michigan visited Moscow to learn about Fyodorov’s work. Bores returned to Moscow a year later to confirm that RK patients enjoyed good long term results. He invited Fyodorov to lecture at the Kresge Eye Institute in Detroit in 1978. However, ophthalmologists in the U.S. were hesitant to accept RK; many felt cutting healthy corneas was too risky.
Vision correction surgery received a big boost when it was shown that lasers can be used to modify the cornea. Laser eye surgery proved to be faster, more precise, and pain free. I wrote earlier about how Charles H. Townes invented the laser.
Briefly, the operation of the laser is based on an amazing phenomenon called population inversion. An atom with an electron in the excited state emits a photon when the electron drops to the ground state. Einstein realized that an atom with an electron in the excited state can also be stimulated to emit a photon when merely grazed by another photon—turning one photon into two photons. Meanwhile, atoms in the ground state become excited when they absorb photons. If absorption of photons by atoms in the ground state and stimulated emission by atoms in the excited state take place simultaneously, there will soon be more atoms in the excited state than not. If there are more atoms in the excited state, more photons will be emitted than absorbed, and the light used to initiate the process is amplified.
A type of laser well suited to surgery was developed in 1970: the excimer laser. An IBM researcher, Rangaswamy Srinivasan, discovered in 1981 that excimer lasers can be used to finely etch living tissue without damaging surrounding tissue. Each laser pulse removes just 39 millionths of an inch of tissue. Srinivasan teamed up with Steven Trokel, an ophthalmologist at Columbia University, to show that use of the excimer laser was safe and effective.
In the early 1990s, two researchers working independently—Ioannis Pallikaris and Lucio Buratto—used microkeratomes to create and lift corneal flaps, ablate the exposed corneal beds, and replace the flaps. Pallikaris dubbed the technique laser assisted in-situ keratomileusis, or LASIK. Clinical trials of LASIK in the U.S. began in 1996 and the procedure was FDA approved in 1999. In one of the first studies, 70% of approximately 500,000 Americans who underwent LASIK surgery emerged with 20/20 vision.
LASIK is surgery and all forms of surgery entail risk. Many patients fail to obtain 100% correction; while a second procedure is possible it is discouraged. Proponents point out that the risk of serious problems is less than 1%. Critics say that’s still unacceptable.
Ophthalmologists use advanced technology for a number of other purposes including detailed mapping of the cornea; replacing the eye’s crystalline lens when it becomes clouded with an implantable intraocular lens (IOL); and treating detached retinas, secondary cataracts, age-related macular degeneration (AMD), and glaucoma.
The history of ophthalmology reminds us that technology can often achieve more than at first seemed likely. After all, the eye is a very delicate organ. Who would have guessed that vision can be improved by cutting the cornea? Or that the eye’s crystalline lens can be removed and replaced with a man made lens?
Next time: Technology with Real Teeth
Note: If you would like to be notified when The History & Future of Medical Technology is published, please go to Telescope Books and enter your email address in the newsletter sign-up field on the left menu bar. This email list is only used to announce book offers from Telescope Books; your email address will not be shared with third parties.