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WHITE HOUSE CONFERENCE REPORT
CHANGES ASSOCIATED WITH AGING
Aging, in its broadest sense, is a biological phenomenon that occurs in every living organism. Although it is difficult to narrow down to an exact definition, it might be best described as "the period when growth or proliferation has ended but the powers of regeneration still remain (Mazow, 1958)". It does not occur in all human beings at the same age, because it is controlled by such factors as heredity and environment, both variables.
When "senescence" or aging takes place, changes in tissue occur to cause visual as well as other disorders. Not all tissues and organs are affected at the same time, because not all of them reach their optimum performance at the same time.
In addition, general systemic changes occur universally in almost everyone over the age of 40, taking into consideration the considerable variations and differences of physiological and chronological ages in individuals. Few people, if any, reach old age without some complications caused by disease, particularly of a degenerative nature. The most common are: heart and vessel trouble, cancer, arthritis, rheumatism, and nervous disorders.
To offer maximum benefit to the aging person, the optometrist must take these systemic disorders into consideration, and coordinate his efforts with those of the other practitioners in the health field.
Like the other organs, the eye participates in the aging changes which take place in the human body. It is subject directly to all the degenerative conditions that prevail, and likewise is often affected by disorders occurring in other organs.
From a psychological aspect, optometrists are deeply concerned with understanding the older years, for they are not only involved in correcting certain anomalies and complaints, but also in the practice of training people in the development of certain practical visual skills.
Many studies show some loss of visual acuity (the ability to see clearly) with age. There are many other questions that can be asked when considering the physiological and pathological changes of age on vision. To correct these, accurate measurement is of extreme importance. This has been the basis for the development of numerous physical and statistical methods for accurately measuring acuity, visual capacity and perception.
Although there are definite refractive changes that come with age, a complete understanding is made difficult by the lack of accurate measurability of some of the structures of the eye. The greatest obstacle is the crystalline lens, which unlike most other body structures continues to grow in size throughout life.
Stenstrom, in 1948, established that the refractive state among young adults is more closely correlated with axial length than any other variable or combination of variables. Studies also show that refractive changes are more marked during major growth spurts. Most experts agree that changes in refraction are rare between the ages of 25 and 40. The concern felt by a patient over forty relative to his "failing eyes” might well be the result of his having gone through 20 years or more of vision in which his refractive state has changed very little. A regular periodic examination is still necessary at any age to properly assess individual refractive changes.
The most dramatic change which occurs in aging is in "accommodation”, the ability to change focus from far to near and back. The rate of decrease in ability is fairly gradual and remarkably uniform. There have been, however, some variations leading to proposals that the rate of decrease be used as an aid in predicting the life span of any given individual (Bernstein & Bernstein, 1945).
However, this as yet, has not been proven by longitudinal studies. As the inability to "accommodate" progresses, it eventually becomes necessary to supplement natural accommodation with a convex lens known as an "add". When this occurs, the condition is termed, "presbyopia" or "old age sight”. When most people become aware of their loss of focusing ability for near work, their reaction is that they feel their "arms are too short" for ordinary reading. The supplementary lenses prescribed for older persons to do near work de pend on the amount of accommodation still available, plus the distance of the usual work from the eyes and the size of detail involved.
In addition to the inability to change focus, among aging individuals there is often a change toward lack of binocular control of the eyes. Normal binocular vision requires the intraocular and extraocular neuromuscular mechanisms to operate in a coordinated manner, so that a sharp image can be maintained on both foveas at the same time, without undue effort. As one grows older, the possibility of a pathological involvement of the neuromuscular system greatly increases. Examination of the neuromuscular mechanism involves the investigation of fixation (ability to move an eye in order to place and maintain the image upon the fovea), the versions (ability to move the eyes in the same direction), and vergences (ability to move the eyes in opposite directions).
Some of the changes occurring in the ability to control the eyes that accompany aging are generally agreed to be the result of lack of proper care during the formative years. It is in the area of the visual neuromuscular system more than any other that the value of periodic vision examinations is evident. Many of the physical changes affecting the visual neuromuscular system are indications of serious general pathological problems. It is here that the optometrist as a member of the health team often has an opportunity to aid and correct an aging person's condition. The most important consideration in correcting improper motor coordination of the eyes is the patient himself, his symptoms, his requirements, and his ability to adjust.
EXAMINATION OF THE AGING PATIENT
As the average life span of the American increases, the number of senior citizens also increases. This means that the percentage of patients past the age of 40 will continue to rise. These people require a different approach in many phases of eye care and the diagnostic significance of tests varies considerably. Final prescriptions and recommendations to the senior citizen are based on the physical and mental changes that come with age, as well as the need.
The importance of the physical and visual history of a patient becomes greater with age, for the deficiency of the current visual mechanism often is a result of earlier injury, disease and general physical being. In dealing with aging individuals it has been learned that members of the patient's family can throw a great deal of light on the patient's history, especially in supplying needed details that are lost in the haze of the older individual's memory.
A patient's occupation, hobbies and activities, although perhaps more restricted, take on increased importance after 40. In examining the aging person, details such as location and position of his work, distances and eye levels while engaged in the task are considered. In some cases, actual measurements of working distances are taken. In addition, lighting and general conditions are noted. The amount of fixed attention and prolonged eye use under various conditions are also considered, and often different types of lenses are prescribed for different kinds of visual tasks. It is not unusual for the aging person to require several different types of lenses in order to see more efficiently and comfortably in his varied occupations.
There are a variety of tests used to determine all aspects of the individual's visual acuity and general eye health. Included are external examinations, opthalmoscopic examinations for detailed inspection of the interior of the eye including particularly the lens, retina, nerve head, macular area and vessels; retinoscopy and subjective tests, in order to determine exactly what lenses are needed; phorias and ductions, which are prismatic calculations for correction of neuromuscular disabilities; and, specific nearpoint tests, which assume increased importance for the patient