Popular culture has always endowed human eyes with occult as well as physical powers. Myths and folklore ascribe to the eye the qualities of omniscience, evil, beneficence, spirituality and sensuality, to name only a few. Language itself endows vision with a broad range of meaning. For example, we say "I see," reinforcing the idea of vision as knowledge.To "see" is to understand. To have a "viewpoint" implies an opinion. To have "foresight" signifies unusual perception, and so forth.

The exhibition, In The Eye of the Beholder: Sight, Illusion and Disorder, at The University of Iowa Hospitals and Clinics Medical Museum, expresses the function, anatomy and pathology of the eye through imagery, text and artifact. The eye-brain connection is presented through interactive exhibits demonstrating color perception and optical illusions, that encourage visitors to apply practice to theory.

1. Ophthalmology Ward, State University of Iowa Hospitals, 1904. Photo courtesy of the University of Iowa Libraries, Archives.

The sensory mechanism of sight is complex and involves more than the eyes moving in tandem -- the brain also plays a fundamental role in producing vision. Our eyes can sense ten million gradations of light and seven million shades of color, but only about 75 percent of what we perceive derives from what we see; the brain fills in the missing links. The brain also filters out confusion images -- such as the shadow of blood vessels on the retina, and even one's own nose. Some aspects of normal vision must be learned, unlike the sense of touch or hearing. For example, the ability to perceive depth is acquired with experience. Learning to make effective use of reduced vision is certainly a survival skill in our aging society.

Eye therapies often involve sight-saving measures to reduce further deterioration. In some cases vision can be restored. Corneal transplants and cataract removal can replace a clouded view of the world with one that is bright and clear. And when an eye is no longer functional, an ocular prosthesis can be so closely matched that few can discern the difference. Examples of the evolution of prostheses are on display, along with photographs of people fitted with artificial eyes. We challenge visitors to identify the latter. Over two dozen pairs of spectacles dating from about 1700 to the present illustrate advances in the technology of optics and the vagaries of fashion. Included in this exhibit are eyeglasses purportedly worn by Abraham Lincoln, "prospect" glasses, lorgnettes and monocles. To better understand the optical properties of eyeglasses, visitors are invited to look through prisms, a diffraction grating, and lenses that correct various refractive errors.

The discovery of antibiotics fifty years ago revolutionized the practice of surgery, including surgery of the eyes. Surgical techniques pioneered by ophthalmologists are frequently adopted by the rest of the medical profession. For example, corneal transplants increased in the 1940s, anticipating methods that would later be applied to the transplant of other organs. To this day, corneal transplants are the most commonly performed and highly successful of all transplant procedures. Microsurgery on the eyes, first developed in the early 1960s, employs such delicate instruments that magnifying lenses must be used to tell them apart. Ophthalmologists were also the first to use laser therapy and anti-viral medications, leading to the extensive use of both in other specialties. Many diseases and injuries of the eye will be anticipated, managed, and eventually cured through further advances in ocular research at The University of Iowa Hospitals and Clinics, The University of Iowa College of Medicine, and similar institutions.