Conjunctiva
The conjunctiva is the thin mucous membrane covering the sclera. Its goblet cells produce mucin, essential for lubricating eyelid movement and providing a protective layer to slow evaporation of the tear film. With aging, the number of mucous cells decreases, either as a result of keratitis sicca (with or without Sjogren’s syndrome) or non-specifically. These changes contribute to dry eye syndrome, manifested by a scratchy sensation and chronic irritation, often with increased redness from conjunctival vascular dilation (see also Lacrimal Gland and Tear Drainage, below). Diagnosis is confirmed by examining the cornea with slit-lamp biomicroscopy, and treatment usually consists of methylcellulose eyedrops (artificial tears) or a variation of them.
The conjunctiva can also undergo metaplasia and hyperplasia. This may lead to tissue accumulation at the nasal or temporal junction of the sclera and cornea, called a Pinguecula. Connective tissue that grows, vascularizes, and invades the cornea is called a pterygium (see FIG. 102-2). If a pterygium continues to grow and reaches the center of the cornea, it can interfere with vision. Pterygia usually occur in people who spend a lot of time outdoors, especially in dusty and windy environments. Frequently occurring in women, Pingueculae may be a cosmetic problem, but they rarely require removal; however, pterygia should be followed, and at first evidence of corneal involvement, surgical excision should be considered.

The sclera is seen more clearly when the overlying conjunctiva is thinning. Arcus senilis, a deposit of calcium and cholesterol salts appearing as a gray-white ring at the edge of the iris, is a common finding in those > 60 yr. Usually, this sign is not associated with systemic disease, although rarely it is linked to systemic hyperlipoproteinemia.

Arcus senilis usually occurs in the cornea, 1 to 2 mm inside the lim-bus, but it will not progress to interference with vision. The major age-related change of the cornea is degeneration of the endothelial cells lining its inner surface. Progressive degeneration can eventually result in failure to keep the cornea free of extracellular fluid. The resulting corneal edema and accompanying hazy appearance interferes with vision and may require corneal transplantation. The hazy appearance of the cornea requires referral to an ophthalmologist.

The iris contains two sets of muscles that regulate pupillary size and reaction to light. With age, the pupil becomes smaller, reacts more sluggishly to light, and dilates more slowly in the dark. Thus, elderly persons may complain that objects are not as bright (a smaller pupil allows less light to enter the eye), that they are dazzled when going outdoors (slow pupillary constriction), and that they experience difficulty when going from a brightly lit environment to a darker one (slow pupillary dilation). If visual acuity is normal, only reassurance is needed.
Relative pupillary size and reaction to light can be evaluated in a dimly lit room by shining a penlight obliquely into each eye and observing constriction of the pupil in the illuminated eye and the contralateral eye. Because pupillary diameter decreases with age, the direct and consensual reactions to light tend to be reduced. If the pupillary response is sluggish or absent, the patient may be taking medication that causes pupillary constriction or dilation.

Ophthalmoscopy of the retina is difficult in elderly patients because of their small pupils, eye movement, and opacities, but providing a target to stare at may help. Such an examination provides the only opportunity to directly visualize a cranial nerve (optic nerve), the portion of the retina responsible for the highest level of visual acuity (the macula), and blood vessels (retinal artery and vein and capillary bed). Recognizing age-related changes in these structures is important.
The optic nerve tends to have less distinct margins and may appear slightly paler because of a loss of capillaries from small-vessel disease secondary to atherosclerosis. The macula, which in young people usually has a bright central foveal light reflex, may not have any foveal reflex. Also, yellowish-white spots (drusen) often appear in the macular area, and some disruption may occur in the pigmentation pattern (see AGE-RELATED MACULOPATHY, below). Unless these macular changes are accompanied by a distortion of objects or a frank decrease in visual acuity unexplained by other causes, they are not clinically important. The arteries also demonstrate atherosclerotic changes, including slight narrowing and an increased light reflex from thickened vessel walls. The veins may show marked venous indentation (nicking) at the arteriovenous crossings with slight proximal distention. In general, the retina, which glistens in younger people, becomes duller with aging.

Evaluation of the symptoms and signs associated with disorders of the aging eye and visual axis must be based on an understanding of anatomy and physiology. FIG. 102-1 depicts the structures that undergo anatomic or physiologic changes with aging.
OCULAR STRUCTURES
Conjunctiva
The conjunctiva is the thin mucous membrane covering the sclera. Its goblet cells produce mucin, essential for lubricating eyelid movement and providing a protective layer to slow evaporation of the tear film. With aging, the number of mucous cells decreases, either as a result of keratitis sicca (with or without Sjogren’s syndrome) or non-specifically. These changes contribute to dry eye syndrome, manifested by a scratchy sensation and chronic irritation, often with increased redness from conjunctival vascular dilation (see also Lacrimal Gland and Tear Drainage, below). Diagnosis is confirmed by examining the cornea with slit-lamp biomicroscopy, and treatment usually consists of methylcellulose eyedrops (artificial tears) or a variation of them.
The conjunctiva can also undergo metaplasia and hyperplasia. This may lead to tissue accumulation at the nasal or temporal junction of the sclera and cornea, called a Pinguecula. Connective tissue that grows, vascularizes, and invades the cornea is called a pterygium (see FIG. 102-2). If a pterygium continues to grow and reaches the center of the cornea, it can interfere with vision. Pterygia usually occur in people who spend a lot of time outdoors, especially in dusty and windy environments. Frequently occurring in women, Pingueculae may be a cosmetic problem, but they rarely require removal; however, pterygia should be followed, and at first evidence of corneal involvement, surgical excision should be considered.
Sclera
The sclera is seen more clearly when the overlying conjunctiva is thinning. Arcus senilis, a deposit of calcium and cholesterol salts appearing as a gray-white ring at the edge of the iris, is a common finding in those > 60 yr. Usually, this sign is not associated with systemic disease, although rarely it is linked to systemic hyperlipoproteinemia.
Cornea    .
Arcus senilis usually occurs in the cornea, 1 to 2 mm inside the lim-bus, but it will not progress to interference with vision. The major age-related change of the cornea is degeneration of the endothelial cells lining its inner surface. Progressive degeneration can eventually result in failure to keep the cornea free of extracellular fluid. The resulting corneal edema and accompanying hazy appearance interferes with vision and may require corneal transplantation. The hazy appearance of the cornea requires referral to an ophthalmologist.
Iris
The iris contains two sets of muscles that regulate pupillary size and reaction to light. With age, the pupil becomes smaller, reacts more sluggishly to light, and dilates more slowly in the dark. Thus, elderly persons may complain that objects are not as bright (a smaller pupil allows less light to enter the eye), that they are dazzled when going outdoors (slow pupillary constriction), and that they experience difficulty when going from a brightly lit environment to a darker one (slow pupillary dilation). If visual acuity is normal, only reassurance is needed.
Relative pupillary size and reaction to light can be evaluated in a dimly lit room by shining a penlight obliquely into each eye and observing constriction of the pupil in the illuminated eye and the contralateral eye. Because pupillary diameter decreases with age, the direct and consensual reactions to light tend to be reduced. If the pupillary response is sluggish or absent, the patient may be taking medication that causes pupillary constriction or dilation.
Retina
Ophthalmoscopy of the retina is difficult in elderly patients because of their small pupils, eye movement, and opacities, but providing a target to stare at may help. Such an examination provides the only opportunity to directly visualize a cranial nerve (optic nerve), the portion of the retina responsible for the highest level of visual acuity (the macula), and blood vessels (retinal artery and vein and capillary bed). Recognizing age-related changes in these structures is important.
The optic nerve tends to have less distinct margins and may appear slightly paler because of a loss of capillaries from small-vessel disease secondary to atherosclerosis. The macula, which in young people usually has a bright central foveal light reflex, may not have any foveal reflex. Also, yellowish-white spots (drusen) often appear in the macular area, and some disruption may occur in the pigmentation pattern (see AGE-RELATED MACULOPATHY, below). Unless these macular changes are accompanied by a distortion of objects or a frank decrease in visual acuity unexplained by other causes, they are not clinically important. The arteries also demonstrate atherosclerotic changes, including slight narrowing and an increased light reflex from thickened vessel walls. The veins may show marked venous indentation (nicking) at the arteriovenous crossings with slight proximal distention. In general, the retina, which glistens in younger people, becomes duller with aging.

Lids
With age, the lid margins (especially the lower one) can fall away from the eyeball (ectropion). This usually results from decreased strength of the orbicular muscles of the eyes, which squeeze the lids shut. If the lower lid margin no longer touches the eyeball, the punctum of the medial lower lid no longer touches it either, and tears cannot drain properly from the conjunctival sac into the lacrimal sac (see FIG. 102-3). Thus, patients complain of excess tear production and tears draining onto the face (see also Lacrimal Gland and Tear Drainage, below).
With decreased action of the orbicular muscles, the lids may not close completely during sleep, resulting in corneal drying and secondary abrasion, redness, and irritation (superficial punctate keratitis). Spasm of the orbicular muscle of the eye may cause the lid margin (especially the lower one) to turn in (entropion), bringing the eyelashes in contact with the eyeball and allowing them to rub it with each blink, resulting in chronic irritation. Over time, corneal and conjunctival scarring may result if this condition (trichiasis) is not corrected surgically.
For unknown reasons, some people have bilateral intermittent or constant severe spasms of the orbicular muscles of the eyes, so that the eyelids are shut tightly for periods varying from seconds to minutes. This blepharospasm can incapacitate a person and often must be treated by partial surgical denervation of the orbicular muscles. More
Orbit
With age, the loss of periorbital fat often causes the eyeball to sink into the orbit (enophthalmos). Although asymptomatic, enophthalmos often poses a cosmetic problem and may require surgery.

Headache
In the elderly patient, three general types of headaches can be distinguished: tension headache, eye muscle pain, and vascular headache. Patients with acute ocular disorders such as acute glaucoma may also complain of headache.
Tension headache: This headache is related to any cause of increased muscle tone, eg, stress, arthritic pain, fatigue, or anxiety. These conditions may lead to chronic spasm of the scalp, the face, or the six extraocular muscles that control eye movements. Over time, the spasmodic muscles accumulate lactic acid, which stimulates local pain receptors, resulting in headache. Such a tension headache is usually described as a tight band about the head or as pressure, and in most cases can be related to a specific activity. The headache worsens if the activity continues and is often relieved by muscle relaxants or analgesics. Occasionally, however, the pain is truly debilitating.
Eye muscle pain: This type of headache often presents as a brow ache, first occurring on awakening, especially if the patient was reading or watching television late the previous night. The pain can be a throbbing, dull ache localized behind one or both eyes or across the brow or the entire forehead. It may affect either side of the head. Other symptoms include redness, burning, and tearing, especially after prolonged close-range work or reading at night when fatigued.
A major cause of this type of headache is a tendency for the eyes to turn outward with aging (exophoria). This results from a gradual decrease in the tone of the medial rectus muscles, which turn the eyes inward when reading or focusing on objects within 1 to 10 ft.
Exophoria is diagnosed by asking the patient to look through reading glasses at a flashlight about 1 ft away while alternately covering each eye, never allowing both to see the light simultaneously. Each eye is observed as soon as it is uncovered. If the eye moves inward to look at the light, it must have drifted outward while it was covered, suggesting exophoria.
Headache associated with exophoria can often be prevented by resting more, doing close-range work early in the day, or increasing the contractile tone of the medial rectus muscles through muscle exercise therapy.
Vascular headache: In the elderly, a vascular headache may result from temporal arteritis or a migraine. When a headache has a recent onset and is associated with hip-girdle pain, jaw claudication, fatigue, or visual changes, the physician should suspect temporal arteritis and obtain an erythrocyte sedimentation rate. If the erythrocyte sedimentation rate is elevated or if suspicion is high before the test results are known, prednisone 60 mg/day should be initiated, and a temporal artery biopsy should be obtained as soon as possible (see also Ch. 74).
Migraine headaches may occur at any age but do not commonly begin in later life. The headache is often preceded by an aura of flashing bright lights in a vertical zigzag or picket-fence configuration, either to the far left or far right of both visual fields, and is always bilateral. This aura may be followed by severe, pounding, relentless pain on the opposite side of the head. The pain is exacerbated by bright lights or movement and eased by lying down in the dark. The aura is caused by marked cerebral vasoconstriction involving vessels of the visual cortex, and the pain results from marked secondary vasodilation (with associated stretching of perivascular nerve endings).
Prophylaxis with a ?-blocker or calcium channel blocker may prevent the attack by blocking vasoconstriction. Effective treatment consists of taking ergotamine at the onset of the aura to abort the attack by maintaining vasoconstriction. Once headache supervenes, analgesics and rest are indicated. An injection of sumatriptan may ameliorate the symptoms.

Tension headache: This headache is related to any cause of increased muscle tone, eg, stress, arthritic pain, fatigue, or anxiety. These conditions may lead to chronic spasm of the scalp, the face, or the six extraocular muscles that control eye movements. Over time, the spasmodic muscles accumulate lactic acid, which stimulates local pain receptors, resulting in headache. Such a tension headache is usually described as a tight band about the head or as pressure, and in most cases can be related to a specific activity. The headache worsens if the activity continues and is often relieved by muscle relaxants or analgesics. Occasionally, however, the pain is truly debilitating.

Eye muscle pain: This type of headache often presents as a brow ache, first occurring on awakening, especially if the patient was reading or watching television late the previous night. The pain can be a throbbing, dull ache localized behind one or both eyes or across the brow or the entire forehead. It may affect either side of the head. Other symptoms include redness, burning, and tearing, especially after prolonged close-range work or reading at night when fatigued.
A major cause of this type of headache is a tendency for the eyes to turn outward with aging (exophoria). This results from a gradual decrease in the tone of the medial rectus muscles, which turn the eyes inward when reading or focusing on objects within 1 to 10 ft.
Exophoria is diagnosed by asking the patient to look through reading glasses at a flashlight about 1 ft away while alternately covering each eye, never allowing both to see the light simultaneously. Each eye is observed as soon as it is uncovered. If the eye moves inward to look at the light, it must have drifted outward while it was covered, suggesting exophoria.
Headache associated with exophoria can often be prevented by resting more, doing close-range work early in the day, or increasing the contractile tone of the medial rectus muscles through muscle exercise therapy.