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Serendipity at Work |
In a sense, perhaps, they had been, for the Zeiss photocoagulator had several disadvantages. It emitted light at a wide range of wavelengths, from 400 to 1,600 nanometers--a potential danger to the eye. Also, its light beam was wide, creating lesions about 500 to 1,000 micrometers in diameter, or about the size of the end of a paperclip. And because the wide beam required maximal dilation of the pupil, the treatment often caused pain when a patient's iris contracted during the 250 to 1,000 milliseconds required to produce the necessary burn. The ruby laser , in contrast, produced light at precisely 694.3 nanometers,  and its beam was tightly directional. It could coagulate a spot on the retina as small as 50 micrometers, about the diameter of a human hair, and do so in 0.2 to 1.0 millisecond--a striking reduction in time.
Over the next half decade, two groups, one on each coast of the United States, conducted critical laser experiments in ophthalmology. On the East Coast were Charles Campbell, of the Institute of Ophthalmology at Columbia-Presbyterian Medical Center in Manhattan (which had received one of the first Zeiss photocoagulators in 1959), and Charles Koester, at the American Optical Corporation in Southbridge, Massachusetts. Before the end of 1960, Koester was involved in starting a research program on laser photocoagulation, and he soon brought Campbell into the project. In the fall of 1961 the two carried out the first therapeutic application of a laser on a human subject, using a prototype ruby laser photocoagulator to destroy a patient's retinal tumor.
The West Coast group was based at Stanford University. In 1955 Milton Flocks, a researcher on the clinical faculty at Stanford, and Christian Zweng, a member of the Stanford faculty and a practicing ophthalmologist at the Palo Alto Medical Foundation, attended a conference at which Meyer-Schwickerath described the Zeiss photocoagulator. They were so impressed that they applied for a grant from the National Institutes of Health to obtain one of the instruments when they became available in the United States four years later. When Flocks and Zweng began looking into using lasers, they collaborated with physicist Narinder Kapany, who founded Optics Technology in 1960. The Stanford team performed its first laser surgery on a human subject in August 1963; less than a year later, at the annual meeting of the American Medical Association (AMA) in June 1964, they presented the results of the ruby laser treatments on 25 patients.
Also at that meeting was Milton Zaret, of the New York Medical Center, who was interested primarily in the effects of radiation on humans. In 1961 he had published one of the first scientific papers on the laser's potential danger to the eye. Although he also recognized the laser's therapeutic potential, Zaret expressed concern at the AMA meeting that researchers did not yet know the laser's long-term effects on either human patients or the operators who were repeatedly exposed to its radiation. The medical community took these cautions to heart and devoted considerable effort over the next few years to devising safe laser devices specifically designed for medical use.
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