FIGURE 2.2 Schematic diagram of an arthroscope, a rigid viewing scope commonly used for knee surgery. A variety of surgical tools can be passed through the working channels of the scope. (Courtesy of T Narashima, Scientist/Imagemakers.)

increasingly replacing glass and with continued growth in the use of antireflection and ultraviolet (UV) blocking coatings. An additional change is the move from bifocal and trifocals with discrete zones to progressive lenses where the refractive correction varies smoothly from the bottom of the lens. Many manufacturing changes for ophthalmic optics are being implemented to enable these advanced features to be delivered to the consumer on demand (in an hour). These evolutionary developments are important but are outside the main interest of this report and are not discussed in more detail.

Introduction of Lasers

The medical potential of the laser has been explored almost from the invention of the ruby laser in 1960. These initial experiments were often of the ''point-and-shoot" variety, unguided by an understanding of the mechanisms by which the laser interacted with tissue or of ways to optimize these interactions. Ophthalmology was the specialty that adapted and incorporated laser techniques into clinical practice most rapidly, in large part because the interior of the eye was optically accessible (Krauss and Puliafito, 1995). By the end of the 1960s, some understanding of the mechanisms by which the laser interacts with the retina had been obtained, with both thermal and mechanical effects identified.

BOX 2.1 TELEMEDICINE

Telemedicine has the potential of bringing access to medical specialists to remote communities in the United States such as Indian reservations, to underserved communities in the United States, and to the entire world. The use of high-speed communications systems to transfer medical images, such as x-ray radiographs and optical micrographs of histology specimens, has been demonstrated at a number of sites. One major East Coast hospital regularly receives and reads radiographs from Saudi Arabia, returning reports within the same day. The use of teleconferencing systems to allow medical consultations involving patients who may be thousands of miles from physician consultants is also being studied in pilot projects. The technology underlying these systems is discussed in more detail in Chapter 1; it includes the development of fiber-optic communications networks and image processing and computational schemes allowing image compression. However numerous financial and legal issues must be clarified, including the malpractice aspects of teleconsultations.

Several groups are developing CCD arrays for the detection of x rays used in medical imaging. When commercialized, such devices will provide x-ray image information directly in digital form, avoiding the need to scan and digitize conventional x-ray film, and will facilitate the transport and storage of radiographs.



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