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Eye diseases and visual impairment Torna agli editoriali

Anna Giulia Cattaneo, M.D.
University of Insubria, DBSF, via J-H. Dunant, 3 - 21100 Varese.

Between sensorial changes reducing autonomy and quality of life, visual impairment is a most important one, frequently increased in the elderly. Vision loss usually imposes to the older person the presence of a home assistant, or the residence in a nursing home, it can cause accidents and falls, with devastating consequences on the frailty of the older subjects. The impact on economical burden, not only the familial one, but even for the public health care, imposes a careful diagnosis and the appropriate use of preventive and therapeutic measures, as requested. The entire eye and its structures can be affected by age-associated damage. More common pathological conditions can be summarized as follows.

1. Cornea and conjunctiva can be injured by at least two pathologies quite common in the older person.
The dry eye is the effect of tears production inadequacy; in elderly it can be due to multiple factors, unequally injuring the tears producing structures (meibomian glands, main and accessory lachrymal glands, and by the goblet cells). This pathological condition can cause corneal opacities and keratoconjunctivitis, and it is common enough to be a concern for costs of public care. Symptoms include ocular discomfort and pain, photophobia, various degree of visual loss, temporary or permanent. Adequate strategies must support diagnosis and outcome. Older age (65 years and more) is a generally recognized risk factor. A number of underlying conditions are associated with dry eye, in particular malnutrition (vitamins and oligoelements deficiency), autonomic dysfunction (as seen in diabetes and in Parkinson disease), infections and inflammations, and their sequel involving lachrymal glands, or autoimmune disease (in older subjects mainly represented by the Sjögren's syndrome and the rheumatoid arthritis). Other causes of keratitis and conjunctivitis (Grave's disease, use of contact lens or atopic conjunctivitis, as an example) are not related to the old age, and are out of the limits of this Editorial.

The second cause of possible traumas for both the cornea and the conjunctiva is the eyelid retraction, due to chronic inflammation and infection, dermal sclerosis and alterations of connective and elastic fibres. This condition substantially alters the eye physiology, and can damage the eye as a consequence of inappropriate distribution of the tear film, in addition to the direct trauma due to the contact with eyelashes.

Preventive measures include adequate treatment of underlying or associated diseases, improvement of hygiene and nutrition, early detection and diagnosis of any cause of ocular discomfort, avoid fatigue and frequent rubbing of eyelids, adequate use, not misuse, of eye drops. Therapy vary widely, from very simple measures, as the use of tears replacement, to medication (antinflammatory drugs, pilocarpine and agents acting on the autonomic system, immunity depressant, and others), or even surgery, for more serious cases and complications.

2. Another age-related condition impairing visual acuity is the cataracts. Senile opacities of the lens can be due to nuclear sclerosis, cortical and subcapsular (both anterior and posterior) cataract. Various degrees of visual impairment are the most important symptoms, to be supported by examination of the eye anterior chamber. In addition to older age, diabetes mellitus and overexposure to UV radiation can cause the same ocular defect: the role of oxidative damage has been postulated and in part demonstrated in all these conditions. The only type of cataract associated with the Werner syndrome, an accelerated aging process due to a genetic defect, is instead subcapsular. The preventive measures are efficient only if they are long-lasting. They include protection from UV and ionizing radiation (life-long, or as long as possible), nutritional measures, like long-term high intake of vitamin C, A and E and other antioxidant to the diet, and, of course, a careful treatment of diabetes mellitus, when present. Eye drops containing N-acetylcarnosine have been proposed as protective against progression of the opacity. However, reversion of an incipient cataract is an improbable purpose, and surgery is the treatment of choice for established lens opacities. The improvement of visual acuity is rapid (40-50% after 3 months) and progressive (>80% 2 years later).

3. Glaucoma recognizes a genetic predisposition, however it is also a well known consequence of diseases (diabetic retinopathy, vitreous detachment, and cataract), or it can be iatrogenic: malpractice in medications and ocular surgery can be responsible of it. Signs and symptoms differ in acute angle-closure and in open-angle glaucoma. The first is an emergence characterized by the "red eye", with conjunctival injection, severe pain and elevated intraocular pressure, and must be promptly differentiated from other acute diseases involving the eye (mainly conjunctivitis, iritis or keratitis). In elder people it can follows distortions of the anterior chamber due to surgery on the lens, or aphakia. The open angle glaucoma is by far most common, and has been recognized as an age-associated condition. Its incidence should increase in the near future, as predicted by a recent study (Eur J Ophthalmol. 2007 Jan-Feb; 17(1):45-52). Headache, myopia and progressive visual impairment can be associated. Preventive measures include a precocious selection of patients at risk on the basis of anamnesis (genetic risk is important), precocious diagnosis, correction of associated diseases, knowledge of drugs adverse reactions and cautious use of medications. Accurate asepsis and skill in performing eye surgery, even in minimally invasive manipulations, are required. Therapy is based on medication or surgery.

4. Diabetic and hypertensive retinopathies in aged persons follow the rules and outcome common to their causative diseases. The prevalence and duration of underlying diseases is positively correlated with the higher prevalence and severity of retinal complications in elderly people. Prevention is based on effective and long-lasting management of diabetes and hypertension, the choice of drugs must take into account the frailty of the old subjects and the eventual presence of co-morbidity and multiple drug intakes. While adequate treatment of hypertension usually cure also the retinopathy, the macular oedema and proliferative retinopathy due to diabetes requires laser photocoagulation to maintain vision. In certain cases, vitrectomy is required.

5. The disease probably more typical of the old age is the senile macular degeneration. This disease, causing a progressive and serious visual impairment, is primarily associated to the aging process in genetically predisposed individuals. It behaves as a lat-onset inherited disease. The role of an oxidative damage superimposed to the genetic trait has been proposed. A damage of the outer segment of cones associated with altered composition of retinal pigments is followed by altered properties of the Bruch's membrane of the choroids and by accumulation of debris, seen at the ophthalmoscope as whitish extrusions called "drusen". Choroidal revascularization follows. Their excessive presence in the macular region is distinctive of senile macular degeneration. Associated risk factors, in addition to genetics and aging, are few and poorly documented: cigarette smoking and nutritional deficiencies, especially of vitamins and zinc, seems to be supported by some evidence. Preventive measures are not known, except for safer life style concerning nutritional and not-smoking habits. Established therapeutic measures are based on laser photocoagulation. A number of alternative types of treatment, ranging from anti-angiogenic medications, photodynamic and low-dose radiation therapy, or surgical intervention for macular translocation and even embryonic cells transplants have been experimentally proposed. The disease remains one among the most important causes of visual impairment and blindness in older age, in absence of concomitant diseases.

The interested people can eventually read a review, like that recently appeared in Am J Nurs. 2006 Nov;106(11):52-61. Other diseases and lesions to the eye and its surroundings structures, impairing visual acuity but not typically associated with elderly exceed the limits of this Editorial.

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