What is optometry?

Science and Profession

Optometry has been defined as “the art and science of vision care” by Monroe J. Hirsch and Ralph E. Wick in The Optometric Profession (1968). The American Optometric Association has stated that “Doctors of Optometry are independent primary health care providers who specialize in the examination, diagnosis, treatment and management of diseases and disorders of the visual system.” Optometrists examine eyes and the visual system. They prescribe spectacles and contact lenses, optimize binocularity (the manner in which the two eyes work together), and improve visual function. Optometrists are trained to detect, treat, and manage disorders and diseases of the eyes and related structures.

Optometry is one of the youngest of the learned professions, which were originally restricted to law, medicine, and theology. Following the earlier lead of organized medicine, optometrists successfully organized and passed the first optometry practice law in 1901. Optometrists today complete a university education and then spend four additional years in a specialized school or college of optometry to receive the OD (doctor of optometry) degree. Many optometrists spend an additional year training in special-interest residency programs after graduation. Optometrists practice independently in private offices, although increasing numbers of optometrists also work in groups, the military, public health agencies, and university and hospital environments.

Distinctions are made between optometrists, ophthalmologists, and opticians. Ophthalmologists are physicians who diagnose and treat eye diseases and who perform eye surgery. They complete a premedical university education, four years of medical school, one year of internship, and three or more years of specialized training in ophthalmology. Many ophthalmologists also complete one or more years of fellowship subspecialty training. Opticians are technicians trained in the manufacture and dispensing of optical aids.

Diagnostic and Treatment Techniques

A portion of the eye examination performed by optometrists is called clinical refraction. To the physicist, refraction is the bending of light as it passes through an interface separating two differing media (such as water and air). Refraction, however, has also come to mean the clinical evaluation of the human visual system. Clinical refraction generally results in a spectacle prescription; such a prescription will contain the spherical optical power, and the astigmatic optical power and its axis when appropriate, that are necessary to provide optimally focused light on the retina for each eye.

A clinical refraction also includes an assessment of binocularity, which is the way in which both eyes are used simultaneously such that each retinal image contributes to the final visual percept. (The retina is the inner nerve layer of the eye upon which the optics of the eye focuses the image of the outside world.) Much effort is made, during a refraction, to attain maximum visual comfort by optimizing binocularity. Occasionally, it is necessary to utilize a prismatic element in the spectacle prescription as well as optical powers to this end. In other cases, the clinician may suggest a course of eye exercises to assist the patient in achieving improved binocularity without, or in supplement to, spectacles. Some patients may be found to suffer from severe binocular dysfunction and are referred for surgical consideration.

Near vision is tested during a refraction, especially for those people more than forty years of age who might require optical assistance for near work. The cornea is the clear, circular “window” in the front of the eye through which the colored iris is seen. Behind the iris is a crystalline lens. The cornea and the lens act together to focus light on the retina. The cornea provides most of the refractive power of the eye, and the lens serves to fine-tune the image in a process called accommodation. As one ages, however, the ability to accommodate deteriorates. Some form of near correction, either with two pairs of spectacles or with some form of bifocal, is then necessary. Only minimal optical power is needed at first, but as the aging process continues, the need for stronger near correction increases.

For a given patient, an analysis of binocularity, the determination of near vision requirements, and a consideration of additional occupational or avocational tasks (such as sports) make up his or her “functional vision.” For some patients, the data gleaned in a standard refraction will provide the optometrist with all the information necessary to recommend comfortable visual correction for all tasks. For other patients, some additional thought and consideration may be required. For example, a very tall, fifty-year-old patient may not require as strong a reading correction as another shorter individual of the same age because the former has longer arms and is more used to holding reading material at a greater distance than the latter. In addition, providing visual care to patients using computers and video display terminals has become a rapidly growing subarea in functional vision.

No clinical refraction would be complete without an assessment of ocular health. This examination consists of observation of the eyes and related structures, as well as a testing of function. Good visual acuity, in and of itself, is fairly good evidence that the function of the eye is normal. Some ocular diseases, however, may occur and—at least initially—leave central vision intact. The structures of the eye are inspected with the assistance of instruments such as a clinical biomicroscope, or slitlamp microscope, to examine the outer ocular structures, and an ophthalmoscope, which allows inspection of the structures of the inner eye. Pupillary dilation with pharmaceutical agents in the form of drops allows inspection of the peripheral retina. The pressure in the eye should be tested, a process called tonometry, and the field of vision evaluated. Many optometrists also bear the responsibility for the treatment of certain ocular diseases.

As is true for all professionals, when the management of a specific problem is beyond one doctor’s training, interest, or licensure, referral is made to another, more appropriate, doctor. For example, a patient with an age-related cataract (clouding of the crystalline lens) may be referred to an ophthalmologist for surgery, and an optometrist who suspects multiple sclerosis will refer the patient to a neurologist.

There are subspecialty areas in optometry, such as the prescription of appropriate visual aids for patients with particularly poor vision, known as low vision rehabilitation. Other subspecialty areas include industrial vision, developmental vision and vision therapy, and ocular disease. Contact lens care has become a large subspecialty in optometry. In fitting contact lenses, the curvature of the cornea, the quality of the patient’s tears, and the health of the ocular surface and associated structures (such as eyelids) are all important considerations. Contact lenses are usually intended as devices to provide vision as an alternative to spectacles (although there are occasions when contact lenses may be used as prosthetics, to cover a damaged eye, or as therapy for a specific disease). The clinician must modify the original refractive findings to adjust for the placement of the lens because it will rest directly on the ocular surface instead of being attached to a frame half an inch from the eye. The contact lens must be designed so that the surface of the eye is not compromised by its presence. The proper contact lens care system is vitally important for the initial and continued success of a contact lens
fitting. Continuing professional supervision is essential in maintaining optimal vision and safe contact lens wear.

Perspective and Prospects

Evidence suggests that spectacles were first used to assist human vision in Europe at about the end of the thirteenth century. Organizations of spectacle makers were formed in Europe in the fourteenth and fifteenth centuries. These guilds policed the quality of spectacles and the working conditions under which their manufacture occurred. Spectacles were sold to the public in stores and by peddlers. Individuals self-selected the lens or lenses that seemed most appropriate to them for their visual tasks. Retailers selling spectacles eventually began to assist their clientele in making an informed selection. Over time, spectacle vendors evolved into opticians. Some “refracting” opticians tested vision to provide what they believed to be the most appropriate correcting lenses for a particular person. Physicians at that time did not recommend or examine the eyes for spectacles, preferring the use of medication for eye difficulties.

The impetus for optometry’s modern development and legal recognition in the United States began with a confrontation between optometry and ophthalmology. A New York refracting optician named Charles Prentice referred a patient to Henry D. Noyes, an ophthalmologist, in 1892. Noyes wrote Prentice a thank-you note for the referral but suggested that Prentice should not have charged a fee (of three dollars) for his services—such being the right reserved to professionals such as physicians. Prentice responded, defending his practice of charging for his services. Noyes sent Prentice’s letters to another ophthalmologist, D. B. St. John Roosa, who expressed his opinion that Prentice was in violation of the law by charging a fee for his services. By 1895, Roosa had announced that he would seek legislation to prevent opticians from practicing, and Prentice responded by organizing the Optical Society of the State of New York. This society eventually introduced a bill to the New York legislature to regulate the “practice of optometry.” Optometry was defined as refraction, dispensing (that is, selling) spectacles, and related services.

This bill was quite controversial and never came to a vote. Later, however, another New York optometrist, Andrew J. Cross, while visiting Minnesota to teach a program in optics, scoffed at the notion that Minnesota could pass an optometry practice act before New York. Thus inspired, the Minnesotans passed their law, which included a regulatory board, in 1901. Arguing that optometry was separate and distinct from medicine, optometrists proceeded to obtain practice acts in all the states over the next twenty-three years.

Optometrists sought to be professionals rather than businesspeople and developed an agenda that included the formation of organizations: both the American Optometric Association (AOA) and the American Academy of Optometry were established early in the twentieth century. Efforts were made both to reduce the commercial aspects of practice and to improve educational standards. A code of ethics and stringent rules of conduct were adopted by the AOA.

The first American optometric schools were extensions of apprenticeships and offered short courses (one to two weeks) in refraction. Eventually, private schools were established to train both physicians and nonphysicians. Academic programs developed from these independent schools, such as the Southern California College of Optometry and the Illinois College of Optometry. A milestone two-year optometry course began at Columbia University in New York in 1910; Cross and Prentice were instrumental in preparing the curriculum. Ohio State University began a four-year program in 1915, and the University of California, Berkeley, established an optometry course in 1923. By the late twentieth century, seventeen schools and colleges of optometry trained optometrists in the United States; many of the university programs also provided academic postgraduate studies. Similar programs were created in England, Australia, Canada, Europe, Asia, Africa, and South America.

Optometrist and lawyer John G. Classe credits the major change in the way optometry developed in the latter half of the twentieth century to contact lenses and modern tonometry. Prior to technical improvements in contact lenses and tonometry, the practice of optometry was limited and nonmedical. The commercial success of contact lenses brought about research in physiology, which in turn expanded biological knowledge and improved contact lenses. The ability to use a tonometer without drops to test for increased intraocular pressure (a condition called glaucoma) gave optometrists additional responsibility in ocular disease management. Unfortunately, the subsequent changes in practice placed optometry in even greater direct conflict with ophthalmology.

In a meeting held in January 1968, many of the leaders of the schools and colleges of optometry, the chair of the AOA’s Council on Optometric Education, and the editor of the Journal of the American Optometric Association unofficially discussed the future of the profession. Court decisions had ruled that optometrists had the legal responsibility to detect, diagnose, and refer ocular disease, and many optometrists were frustrated by the limited scope of their practice. This group believed that optometry should discard its original concept of being a drugless profession dedicated solely to ocular function. They argued that optometric education should be expanded in the fields of ocular pharmacology, anatomy, physiology, and pathology so that optometrists would become primary entry points into the health care system for patients. Finally, it was concluded that the state laws that govern the practice of optometry should be updated to allow the optometrist to practice what he or she was taught, including the appropriate use of pharmaceutical agents.

In 1971, Rhode Island became the first state to amend its optometry law to permit the use of diagnostic pharmaceutical drugs. Despite continued opposition from ophthalmology, all fifty states followed over the next twenty years. In 1976, West Virginia became the first state to permit the use of therapeutic drugs, and thirty-two states had enacted similar laws by 1993.

Bibliography

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