Although the eye and its supporting structures undergo a number of well-defined changes with age, the distinction between these involutional changes and disease is not always clear cut. For the elderly patient, it is often reassuring to know that the problem is part of a “normal” process rather than the result of a specific illness and perhaps sometimes an artificial demarcation is drawn for the benefit of the patient.
The increase in number of elderly people presents problems in ophthalmology. A high proportion of elderly people instill drops into their eyes, either prescribed for them or as self-medication. It is important that adequate advice is received. Advising the elderly is often time consuming and might entail speaking to a younger relative or neighbour, but an adequate explanation of the disease or problems will avoid anxiety and probably the need for further subsequent unnecessary consultation.
The three commonest diseases of the elderly eye are cataract, glaucoma and age-related macular degeneration (AMD). The first can be cured, the second arrested or prevented, while the third generally tends to run a progressive course and treatment is unsatisfactory at present, although significant progress has been made recently. Attempts to measure the inci- dence of these problems have produced a wide range of figures. Out of a population of elderly persons complaining of impaired vision, about 30% turn out to have a cataract and a similar number to have AMD, whereas 5% or less have chronic open-angle glaucoma. Visual impair-
ment owing to glaucoma is more prevalent and occurs at an earlier age in blacks than in whites.
Although there is an unexpectedly high inci- dence of cataract in patients with chronic simple glaucoma, the association of macular degeneration with cataract or glaucoma is more random.
Changes in the Eyes with Age
The External Eye
The eyelids tend to lose their elasticity and become less firmly opposed to the globe. The upper and lower lid margins become progres- sively lower so that whereas in the infant the upper lid can ride level with or slightly above the corneal margin, in an elderly subject the upper lid might cross a significant part of the upper cornea. An area of white can be seen between the lower margin of the cornea and the lower lid. Some limitation of the ocular movements is accepted as normal in the elderly, especially limitation of upward gaze. The conjunctiva tends to become more lax and a thin fold of con- junctiva might be trapped between the lids when blinking if this becomes excessive. In some elderly patients, there is loss of connective tissue around the lacrimal puncta so that the opening is seen elevated slightly from the rest of the lid. Degenerative plaques are seen on the bulbar conjunctiva in the exposed region
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and the conjunctiva is especially prone to chronic inflammation.
The Globe
Arcus senilis is the name given to the circular white infiltrate seen around the margin of the cornea. The lens gradually loses its plasticity throughout life and this results in a progressive reduction in the focusing power of the eye. This loss of focusing ability is also contributed to by the progressive loss of ciliary muscle tone. A child might be able to observe details of an object held 5 cm from the eye, but as a result of hardening of the lens and weakening of the ciliary muscle, the nearest point at which an object can be kept in focus gradually recedes.
This progressive degeneration tends to pass unnoticed until the eye is no longer able to focus to within the normal reading distance. This usually occurs at the age of 45 years if the eyes are otherwise normal, and the phenomenon is called presbyopia. Some degree of opacity of the lens fibres is common in old age and only when this becomes more extensive is the term
“cataract” used. The pupil becomes smaller with age and does not show the wide range of adjust- ment to illumination seen in younger people.
The vitreous shows an increase in small opaci- ties visible to the subject as “vitreous floaters”.
A more dramatic degenerative change, which occurs in a high proportion of normal individ- uals in the 60–70-year age group, is detachment of the vitreous. The formed part of the vitreous separates from the retina, usually above at first, leaving a fluid-filled gap between the retina and posterior vitreous face. Movement of the vitre- ous face can cause troublesome symptoms, for example flashing lights and floaters, but often a vitreous detachment goes unnoticed and is an incidental finding on examination of the eye.
The important association between sudden vitreous detachment and subsequent retinal detachment has already been discussed in Chapter 13. The appearance of the fundus also shows gradual changes; the retinal arterioles become straighter and narrower, as also do the venules. Colloid bodies or drusen are more com- monly seen because of degenerative changes in Bruch’s membrane and the pigment epithelium, and peripheral chorioretinal degeneration is more evident. The young retina is more shiny than the old retina and in the elderly the normal
light reflex is less marked. The optic disc tends to become somewhat paler and a degree of optic atrophy is accepted by many clinicians as a senile change unrelated to disease.
Eye Disease in the Elderly
The prevalence of blindness increases with age.
The prevalence and causes of blindness also vary from one community to another depend- ing on the age structure of the population and environmental conditions. In England and Wales (1980), the prevalence of blindness was found to be nine per 100,000 children under five years of age and 2324 per 100,000 individuals above 75 years.
A recent survey in the USA has shown that the incidence of cataract in the 45–64-year-old population is 5.6% for males and 2.1% for females. The incidence is slightly higher in the Negro population, and rises to 21.6% for males and 26.8% for females in the 65–75-year-old population. In the same age group (65–75 years), the incidence of AMD is 9.6% for males and 6.9% for females. Both these conditions are, therefore, common and they demand time and medical expertise, both at the primary care level and in hospital.
With increasing longevity throughout the world, especially in the developing countries, there will be a continuing increase in the number of blind people, especially those suffer- ing from diseases related to age, such as cataracts, glaucoma and macular degeneration.
Age-related Macular Degeneration
AMD is the commonest cause of incurable blindness in the elderly in western countries. It is a bilateral disease in which visual loss in the first eye usually occurs at about 65 years of age.
The second eye is involved at the rate of approx- imately 10% per annum and accounts for half of all registered visual impairments in the UK.
There are two main types of AMD: “dry” or atrophic, and “wet” or neovascular. Blindness is usually associated with the wet form of AMD, and among the eyes with severe visual loss, 80–90% of cases are because of wet AMD, while 10–20% are because of the dry form.
Older patients with macular degeneration complain of blurring of their vision and inability
to read. Younger or more observant patients notice that straight edges might look kinked.
Usually one eye is considerably more affected than the other, although both eyes can be affected simultaneously. Because the degener- ative process is limited to the macula, the periph- eral field remains unaffected and the patient can walk around quite normally. Difficulty in recog- nising faces or in seeing bus numbers is also a common complaint. The wet form occurs more commonly in Caucasians and about one-third of the patients give a family history of similar prob- lems. Several preventable factors, including smoking, systemic hypertension, cardiovascular disease and low antioxidant intake, are asso- ciated with increased risk of AMD.
In the early stages of dry AMD, inspection of the fundus shows spots of pigment in the macular region. Drusen are also often seen (Figure 19.1). These are small round yellowish spots, often scattered over the posterior pole.
Unfortunately, the word “drusen” has been used rather loosely in ophthalmology to refer to two or three types of swelling seen in the fundus. It is used to describe the rare mulberry-like tumours seen around the optic nerve head in tuberose sclerosis and it is also used when refer- ring to the multiple shiny excrescences seen on the optic disc as a congenital abnormality.
Drusen seen at the posterior pole of the eye as a senile change are also known as “colloid bodies” and perhaps this term is preferable.
Under the microscope, colloid bodies are seen as a degenerative change in Bruch’s membrane.
Drusen can have varying degrees of hyperpig- mentation. Most eyes with drusen maintain good vision, but a significant number will develop progressive atrophy of the retinal pigment epithelium (RPE) and choriocapillaris.
This is inevitably associated with photoreceptor loss (Figure 19.2). There is usually a moderate loss of vision. This atrophic change in the RPE, choroid and photoreceptors is referred to as “dry” AMD. This is because there is no leakage of fluid or bleeding into the retina or subretinal space.
In the “wet type” of macular degeneration a fan of new vessels arises from the choroid – choroidal neovascularisation (CNV).The growth of these new vessels seems to be important because they invade the breaks in Bruch’s membrane. Serous or haemorrhagic exudate tends to occur and this can be either under the RPE or subretinal (Figure 19.3). A sudden loss of central vision might be experienced as the result of such an episode.Subsequently,“healing”of the leaking vascular complex results in scar tissue formation, which further destroys the central vision permanently.
The terms “classic” and “occult” describe the different patterns of CNV leakage on fluorescein angiography.
Management
No effective treatment is available for dry AMD.
There is an increasing vogue for administering Figure 19.1. Drusen.
Figure 19.2. Dry macular degeneration.
vitamins A, C and E, selenium, copper, zinc, zeaxanthin, carotenoids and lutein preparations to patients. These have been shown to protect against progression of dry AMD to more advanced stages of the disease in high-risk patients. They are thought to reduce the dam- aging effects of light on the retina through their reducing and free-radical scavenging actions.
Some types/stages of wet AMD are treatable.
Currently, there are two clinically proven treat- ments for wet AMD, although the treatment for some eyes is still unsatisfactory.
Controlled trials of the effect of laser photo- coagulation of the choroidal new vessels have shown that this treatment is useful in extrafoveal CNV (i.e., when the leakage is not directly under the fovea). Laser photocoag- ulation ablates the CNV. It is important that those cases that are likely to benefit from treat- ment are first identified quickly. At the present time, this entails photography of the fundus and fluorescein angiography, and infrared angiography with indocyanine green. Often
patients present at the stage when new vessels have already advanced across the macular region to the subfoveal area or where the fovea has already been permanently damaged by haemorrhage or exudate, making effective laser treatment impossible. Only about 10–20% of cases of CNV are eligible for laser photocoag- ulation. Another limitation of laser treatment is the high rate of recurrence of the CNV within a short time following treatment.
The second proven treatment is photo- dynamic therapy (PDT) with verteporfin (Visu- dyne). PDT specifically targets the CNV complex for damage by low-energy laser, but avoids damage to the unaffected tissue, includ- ing the photoreceptors. This treatment aims to preserve vision.
Apart from photocoagulation and PDT, there are other treatment modalities currently under investigation. These include radiotherapy, thermal thermotherapy and drugs including triamcinolone, anercortave, and vascular endothelial growth factor (VEGF) aptamers or Figure 19.3. Wet macular degeneration: a Fundus photograph:
early disease. b Fundus photograph: advanced disease.
c Fluorescein angiogram: early disease.
a
c
b
antagonists, which are delivered via injections into the vitreous.
Practical measures can be taken in the man- agement of these patients to alleviate their handicap. Telescopic lenses might be needed for reading or watching television and full consid- eration should be given to the question of blind registration. It is important to explain the nature of the condition and prognosis to the patient.
This can alleviate considerable anxiety and fear of total blindness and help the patient come to terms with the problem. In most cases, one eye is involved first, the other following suit within one to three years. The vision, as measured on the Snellen chart, progressively deteriorates to less than 6/60, but the peripheral field remains unaffected so the patient is able to find his or her way about, albeit with some difficulty.
Cataract
This common condition in the elderly eye has already been considered, but it is important that every physician can identify and assess the density of a cataract in relation to the patient’s vision. The physician must realise the potential of cataract surgery in the restoration of vision.
Cataract surgery is required only if vision is sufficiently reduced so far as to interfere with the patient’s normal lifestyle. The contraindica- tions for cataract surgery are few and even in extreme old age the patient can benefit. Surgery might be delayed if the patient has only one eye or if there is some other pathology in the eye, which is likely to affect the prognosis. The need for someone to assist the patient in the instil- lation of eye drops and the domestic chores during the postoperative period might require some attention but is not a contraindication.
About one-third of the population aged over 70 years suffers from a cataract, but the quoted figures vary according to the diagnostic criteria.
If an elderly person has an opaque lens, which obscures any view of the fundus with the ophthalmoscope, and the pupil reacts quickly, then he or she is likely to do well after surgery.
It is useful to remember that the reading vision is usually fairly well preserved even when the cataract is quite dense, and if the patient is unable to read, there might be coincidental AMD, except if the cataract is of the posterior subcapsular type.
Glaucoma
The various types of glaucoma have also been considered already, and the reader would realise that glaucoma is simply the manifestation of a group of diseases, each of which has a different prognosis and treatment. Chronic simple, or open-angle, glaucoma is the important kind in the elderly because it often remains undiag- nosed. The physician and optometrist can play a vital part in the screening of this disease by becoming familiar with the nature of glauco- matous cupping of the optic disc. About 1% of the population over the age of 55 years is thought to suffer from chronic simple glaucoma and the figure could rise to as high as 30% in those over 75 years. In most instances, the treat- ment is simple but requires the co-operation and understanding of the patient. The treatment is preventative of further visual loss rather than curative. Chronic simple glaucoma is best managed in an eye unit on a long-term basis. By this means, the visual fields and intraocular pressure can be accurately monitored and the treatment adjusted as required. More recently, the care of glaucoma patients is being shared between hospital units and selected (trained) optometrists in the community.
Deformities of the Eyelids
Both entropion and ectropion are common in the elderly and a complaint of soreness and irritation in the eyes as well as watering should always prompt a careful inspection of the configuration of the eyelids. Entropion is revealed by pressing the finger down on the lower lid so that the inverted lid becomes everted again to reveal the lash line. Sometimes entropion can be intermittent and not present at the time of examination, but usually under these circumstances there is a tell-tale slight inversion of the lid, which is made apparent by compar- ing the two sides. Ectropion is nearly always an obvious deformity because of the easy visibility of the reddened and everted conjunctiva, but slight degrees of ectropion are less obvious. The lower punctum alone can be slightly everted, causing a watering eye, and the symptoms might be relieved by applying retropunctal cautery to the conjunctiva. Both ectropion and entropion respond well to lid surgery and there is no
reason why geriatric patients should put up with the continued discomfort and irritation when a complete cure is readily available. These lid deformities can recur sometimes and require further lid surgery, but careful surgery in the first instance should largely prevent this.
Temporal Arteritis
This condition, also known as giant cell arter- itis, seen only in the elderly, can rapidly cause total blindness unless it is treated in time. The disease is more common than was originally supposed but it is rare under the age of 50 years.
Medium-sized vessels, including the temporal arteries, become inflamed and the thickening of the vessel wall leads to occlusion of the lumen.
Histologically, the inflammatory changes are characterised by the presence of foreign body giant cells and the thickening of the vessel wall is at the expense of the inner layers so that the total breadth of the vessel might not be altered.
In early disease, the inflammatory changes tend to be segmental so that a single biopsy of a small segment of the temporal artery does not always reveal the diagnosis.
Patients with temporal arteritis usually present in the eye department with blurring of vision or unilateral loss of vision. Typically, these symptoms are accompanied by headache and tenderness of the scalp so that brushing the hair might be painful. Often there is low-grade fever and there can be aches and pains in the muscles and joints, as well as other evidence of ischaemia in the brain and heart. Scalp ulcera- tion and jaw claudication can occur. The blur- ring of vision is caused by ischaemia of the optic nerve head or occasionally central retinal artery occlusion. The diagnosis rests largely on finding a raised erythrocyte sedimentation rate (ESR), elevated C-reactive protein levels and a positive temporal artery biopsy in an elderly patient with these symptoms. Palpation of the temporal arteries reveals tenderness and sometimes thickening and the absence of pulsation is a useful sign. Polymyalgia rheumatica is a syn- drome consisting of muscle pain and stiffness affecting mainly the proximal muscles without cranial symptoms.
Inspection of the fundus in a patient with visual symptoms shows pallor and often swelling of the optic nerve head and narrowing of the retinal arterioles (Figure 19.4). Once the
disease is suspected, a biopsy is essential and this should be done without delay. Treatment can be commenced immediately, sometimes even before biopsy. However, it is advisable that the lag between starting treatment and biopsy is as short as possible (preferably less than two weeks). The symptoms disappear rapidly after administering systemic steroids, initially in a high dose (e.g., prednisolone 120 mg per day), and the dosage is then reduced rapidly according to the level of the ESR. Once the ESR is down to normal levels, a mainten- ance dose of systemic steroids is continued, if necessary for several months (on average 18 months).
Temporal arteritis is recognised as a self- limiting condition. About one-quarter of all patients are liable to become blind unless ade- quate treatment is administered and in some instances, extraocular muscle palsies causing diplopia and ptosis can confuse the diagnosis.
For simplicity, one might summarise the disease by saying it causes headache in patients aged over 70 years with an ESR over 70 and who require treatment with over 70 mg of prednisolone.
Stroke
Patients who complain of visual symptoms after a stroke quite often have an associated homony- mous hemianopia and the association between hemiplegia and homonymous hemianopia should always be borne in mind. A simple con- frontation field test might be all that is required to confirm this in a patient with poor vision and Figure 19.4. Giant cell arteritis: ischaemic optic neuropathy.
normal fundi following a hemiplegic episode.
The vertical line of demarcation between blind and seeing areas is well defined and can cut through the point of fixation. Fortunately, the central 2° or 3° of the visual field are often spared. When there is so-called macular spar- ing, the visual acuity as measured by the Snellen chart can be normal. Patients tend to complain of difficulty in reading if the right homonymous field is affected rather than the left, and although they might be able to read individual words, they have great difficulty in following the line of print. Thus, a patient with a right hemiplegia and a right homonymous hemi- anopia might have normal fundi and visual
acuity of 6/6 and yet be unable to read the news- paper. The picture can be further complicated by true dyslexia and the patient might admit to being able to see the paper and yet be unable to make any sense of it. Dyslexia might be sus- pected if other higher functions, such as speech, have been affected by the stroke. One of the fea- tures of a homonymous hemianopic defect in the visual field is the patient’s complete lack of insight into the problem, so that even a doctor might fail to notice it in himself. It is unusual for a homonymous hemianopia to show any signs of recovery, but once the patients understand the nature of the handicap they can learn to adapt to it to a surprising degree.
