Laser vision procedure
Dr. Steve Trokel
(Adapted from an article on www.progressiveyoucansee.org)
More than 70 million people in the United States are nearsighted, farsighted, or have astigmatism (blurred vision at distance or near). Not long ago, the only option for bad vision was obtaining stronger prescription glasses. Today, many patients with a wide variety of vision problems can visit their ophthalmologist, undergo a minimally invasive surgical procedure and go home with perfect vision. Thanks to the hard work of physicians like Stephen Trokel, MD, refractive laser eye surgery is now a common, life-enhancing procedure which has dramatically changed the way vision problems are corrected today.
Although Dr. Trokel was trained in engineering and physics, he ultimately pursued a medical degree in ophthalmology and became intrigued by the diagnostic and therapeutic technologies related to the practice. In the early 1980s, the field of ophthalmology was entering a new era, an era driven by the revolution in laser technology. At that time, while Dr. Trokel was working as a clinical and research professor of ophthalmology at Columbia University, ophthalmologists began using lasers in surgery. “It was like magic for our field,” said Dr. Trokel about the moment when he became interested in using lasers for refractive surgery.
Dr. Trokel was fascinated by this idea and began studying prior laser surgery techniques and made various conclusions of his own, which he documented in several published papers. Dr. Trokel was particularly interested in researching the effect that the excimer laser would have on the human cornea.
The excimer laser, which was invented in the early 1970s, is an ultraviolet chemical laser that has an extremely sharp focus, capable of performing very delicate and precise surgeries, such as eye surgery. “I was astonished, as was everyone, at the precision of the tissue removal by laser,” said Dr. Trokel. “On this small foundation, the technology of excimer refractive surgery was built.” The work of Dr. Trokel and other physician-innovators like him with this technology led to the revolutionary development of what we know today as laser eye surgery.
DEVELOPING THE FUTURE OF SIGHT
In 1982, Dr. Trokel was invited to collaborate with several renowned colleagues who were already working with IBM’s T.J Watson Research Center on the potential of the excimer laser interacting with human tissue. Dr. Trokel shared with them his own research on the interaction of the excimer laser and biological tissues.
Together with these physicians and researchers, Dr. Trokel began performing experiments on animal eyes using the laser for vision correction. They found that by removing a small layer of damaged tissue with the laser, the subject’s vision was improved, and the laser caused little to no heat damage to the neighboring materials of the eye. “Not only did the edge form an optically smooth line, but there was no damage visible at light microscopic resolution,” Dr. Trokel explained.
Dr. Trokel and his colleagues researched both photorefractive keratectomy (PRK) and radial keratotomy (RK). PRK is a surgical procedure that uses an extremely precise laser to remove corneal tissue for the purpose of correcting a refractive error. RK involves making a number of cuts in the cornea to change its shape and correct refractive vision errors. 1 RK can treat only low degrees of myopia and astigmatism, while PRK is useful for treating low to moderate levels of myopia or hyperopia (farsightedness) with or without astigmatism.
The team expanded its research to study corneal specimens that had been exposed to different lasers. Laser excisions were compared to knife incisions and the details of eye surface texture was compared. As their studies advanced, they found that laser usage could be extremely effective for treating myopia, astigmatism and hyperopia.
A NEW ERA OF VISION CORRECTION
Dr. Trokel and his colleagues conducted intense research for several years, and although they were constantly developing the technology, it was not until the successful microsurgical removal of monkey corneas that they began to make serious progress toward the commercial development of laser eye surgery. The corneal experiments on monkeys gave them increasing confidence that tissue could be safely removed from the cornea in humans. With this knowledge, the team began working on ways to bring this technology to a larger patient population.
The first commercial prototype of an excimer laser refined for the specific purpose of eye surgery was produced in 1985 and was shown at the American Academy of Ophthalmology meeting in 1987. The excimer laser is a cold laser that removes fine layers of tissue from the surface of the eye without burning the cornea. After receiving the acceptance of their peers, the group began human testing that same year. Dr. Trokel performed the first laser surgery on a patient’s eye in 1987 with great success.
The subsequent 10 years were spent perfecting the equipment and techniques, making them more viable for wider use. The laser equipment was refined so that doctors could manipulate the device more easily and more effectively, which helped increase the precision of the surgery. The laser itself became more pointed for a better angle of use.
After a series of clinical trials sponsored by a medical technology company and performed by a group of ophthalmic surgeons, the Food and Drug Administration (FDA) approved the excimer laser for ophthalmologic refractive use in the United States in 1996. Dr. Trokel was actively involved with the company in this process, helping with design refinements on the laser, determining its requirements and use and aiding in the clinical study development and implementation.
Since its approval, the excimer laser has had an international track record for safety and effectiveness — with more than 6 million procedures performed to date. Over the last 20 years, excimer refractive surgery has developed into a widely accepted technology that has been successfully applied to millions of patients.
Through further research and collaboration between physicians and medical technology companies, the excimer laser became the foundation for further developments such as LASIK (Laser-In-Situ Keratomileusis) eye surgery. During LASIK, the surgeon uses a mechanical blade or laser to create a thin flap of tissue on the cornea. The flap is folded back, the surgeon uses the excimer laser to gently sculpt the cornea, and the flap is then returned to its original position, adhering without stitches. LASIK has proven to be effective in treating higher degrees of nearsightedness and astigmatism.
The latest generation of LASIK has made vision correction even safer and more effective in treating severe refractive conditions through use of a device called a wavefront analyzer. This innovation creates a 3D map of the patient’s eye that allows the ophthalmologist to customize a laser treatment exclusively for that particular patient. This leads to a safer, more precise, more personalized surgical procedure.
Dr. Trokel sees a bright future for medical technology in the field of ophthalmology. “An important step in the future will be gene therapy and understanding the genetic basis of the eye. This will allow us to have a better control of procedures,” he said. Today, Dr. Trokel sees the new age of laser usage in ophthalmology as a miracle. “I see it in my children and grandchildren. They are getting their teeth fixed as kids but they are already asking ‘when am I going to get my eyes fixed?’ This is something that would not have been possible before. Today, it is just a common fact of life.”