CATARACT AND GLAUCOMA In considering the problem of aging as related to vision, two pathologies of clinical importance should be noted. They are senile cataract and glaucoma. The cataract is defined as "any opacity of the crystalline lens". Although there are other manifestations which occur in individuals of all ages, the "cataract" as we generally know it is primarily associated with senility. The complaint found most frequently among patients suffering cataracts is "my vision blurs" ..."I can't see as well". The degree of loss depends on the nature, extent, and position of the cataract. In addition, there are other symptoms which include distortion of images, and a change in color values and hues. Another symptom quite common is the development of "secondsight". This is a characteristic that the uninformed individual becomes quite proud of, because of a newly acquired ability to read or see at certain distances without his glasses. With the senile cataract, this is often the result of a change in the crystalline lens, which causes the eye to become more myopic or less hyperopic. In such cases, the loss of vision at other distances is often overlooked because of the "improvement" in reading. Fundamentally the exact causes of the senile cataract are unknown. There are a number of suggested causes, including changes in permeability of the lens capsule, changes in the lens proteins, excessive efforts to accommodate, effect of radiant energy on the lens, inadequate nutrition, and systemic disorders such as Diabetes. Surgery at present is the only effective treatment for cataract. Glaucoma is defined by Duke-Elder (1941) as "that pressure which the tissues of the particular eye in question are unable to withstand without damage to their structure or impairment of their function." Of all ocular pathologies, glaucoma is most important to both the optometrist and ophthalmologist, because it is hardest to detect in early stages, and may eventually result in total blind ness. It is estimated that 1 per cent to 2 per cent of patients over the age of 40 have glaucoma, that there is three times as much simple glaucoma as acute, that the greatest incidence of adult primary glaucoma occurs in the 60-70 group (although it should be investigated in persons over 40), that males are somewhat more prone to simple glaucoma than females, but females show a definitely higher incidence of acute glaucoma. Acute glaucoma is seldom found in myopic patients, but chronic simple glaucoma has an incidence which is unrelated to refractive error. It is generally agreed that heredity may play a role in glaucoma. In a report by Posner and Schossman (1949) of 373 patients with primary glaucoma, 51 had one or more relatives afflicted with the same disease. Unfortunately, symptoms are not easily detected clinically, except in acute glaucoma where the patient may complain of such symptoms as pain or headache over the eye, visual disturbances or haziness, the seeing of halos around lights, and the seeing of flashes of light. Other than from diseases, many studies show that loss of visual acuity occurs naturally with age. In the healthy normal adult this loss is very slight, but nevertheless a very real one that often interferes with the aging person's regular activities. Along with age usually comes a steady decline in the ability of the eyes to resist glare. This creates a problem especially in night driving for a person over the age of 60. CONTACT LENSES FOR THE OLDER PATIENT The development of the micro-corneal (small) lens has inspired a great popularity in the wearing of contact lenses. Today, approximately 4 million persons are wearing them, as compared to less than 200,000 just six years ago. The majority of today's wearers are females, estimated to be about 60 per cent of the total. The great majority are also younger persons, and most are first attracted to contact lenses for cosmetic reasons. In males, it has been found that because of the wide field of vision and the safety and convenience values with contact lenses, they are used a great deal to advantage for sports. Aside from sports and cosmetic uses, there are also benefits in wearing contact lenses for certain vision conditions. Those suffering from keratoconus, irregular astigmatism, corneal scarring, aniridia and monocular aphakia are offered an opportunity through contact lenses to find dramatic improvement not possible with ordinary glasses. Of the patients coming to contact lens specialists, 47 per cent are under 25 years old, 45 per cent are between 25 and 40 years old, and only 8 per cent are over 40 years old. The lack of cosmetic incentive to improve one's appearance, a failure to appreciate the optical and physical advantages, and an unwillingness to be inconvenienced during the adaptation period, are no doubt prime reasons for the lack of popularity of contact lenses with older people. Another strong deterrent is the fact that many of these people are presbyopic, which requires glasses in addition to their contact lenses for near-point or reading vision. There are a number of types of bi-focal contact lenses now on the market, and others are in the process of being developed. It is hoped that eventually the advantages of bi-focal correction will be available in a generally acceptable contact lens. The most spectacular use of contact lenses in later maturity occurs after cataract operations. They are generally superior to spectacle corrections for aphakic patients. Their greatest advantage lies in the fact that they practically eliminate all aberrations found with regular glasses, mainly because they move with the eye, rather than the eye moving behind the lens. From a cosmetic viewpoint, the contact lenses do not give the highly magnified eye appearance that the heavy-plus spectacles do, because of the latter's thick convex lenses. The thickness and weight of aphakic spectacle corrections often cause discomfort to older patients, especially during warm weather. Contact lenses for these same people are light in weight, and found to be comfortable once the patient has become adapted to them. Generally, the older aphakic patient becomes adapted to contact lenses faster than the young person, probably because of reduced corneal sensitivity from the incidental severing of some of the corneal nerve fibers during the cataract operation. The future of vision correction through the use of contact lenses opens vast new areas of progress for the aging as well as for the young. PARTIAL VISION AND OPTICAL AIDS The degree of visual acuity in the past was the basis of the three classifications of sight. In the normal range was anyone whose vision checked out at 20/70 or better (the first figure represents the distance in feet at which a line of letters on an eye chart is read, while the second figure represents the distance at which it should be read by a person with "normal" vision). In the second group, called "sub-normal", were those with vision 20/200 or better and less than 20/70. The third was composed of those with vision less than 20/200, and this was called "blindness". Although this arbitrary classification served a useful purpose in problems relative to vision, a more reasonable approach is one based on the positive aspects of vision. This indicates how much a patient can see in contrast to his loss, rather than vice versa. It is acknowledged and agreed that from "above normal vision" to "blindness", there is an entire range of vision possibilities. Any vision, no matter how much below normal, is an advantage, especially if it can be corrected to provide more useful sight. The preferred term of classification of deficient visual acuity might be "partial vision", rather than "sub-normal vision" or "blindness". Practically everyone with vision desires to use the eyes in perception. And with modern techniques, it is the rule, rather than the exception, that partial vision can be improved with optical aids. This is a great boon to the senior citizen, for as he gets older, more and more of his self sufficiency is dependent on vision. Most of the ability to use the knowledge and adeptness gained from a lifetime of experience is controlled by the eyes .... even though in their uncorrected state they might offer only partial vision. From a legal standpoint, the difference between "blindness" and "vision" is strictly an arbitrary one based on the presence or absence of useful vision. The fallacy of identifying limited vision as "blindness" becomes more evident when the following fact is considered Only 25 per cent of the "total blind" people have no perception to light, while the remaining 75 per cent have varying degrees of useful vision, from the bare minimum capable only of giving guidance, to sufficient amounts to allow reading. Many of the senior individuals heretofore classified as "blind" have found that what vision they do have can often be mobilized and made more efficient through the use of various optical aids developed by research in optometry. It is for this reason that the diseases and anomolies that cause impaired vision are of deep concern to the modern optometrist. One of the problems to be coped with by the ophthalmic professions is the "shock" that occurs when an aging person learns that his vision has become impaired. Much of this is due to a lack of understanding or lack of information as to the tremendous strides that have been made in correction and aid. .... In perception, those with impaired vision (especially those requiring optical aids) find a problem in habituation and automazation getting used to the new visual demands, so to speak. It is a matter of changing one's habits in order to use new "vision". This is especially difficult in reading and writing where so much is based on making use of "visual cues" (scanning and tip-off words). Until the individual learns to use his optical aid and automatically "see" without requiring conscious analyzation and interpretation, vision is restricted. Another major problem for the partially-seeing individual is an inadequate rate of perception for meaningful comprehension in reading. It is not at all uncommon to have the rate of perception reduced to individual letters. And since effective reading requires recognition of a group of letters as a word, a group of words as a phrase, a group of phrases as a sentence, and a group of sentences as a paragraph, those with partial vision find reduced ability a difficult handicap, until proper and effective optical correction is made. Mobility, the capacity of facility for movement is another essen 36-2020-64 |