Lip-reading Health Dictionary

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Lip-reading: From 1 Different Sources

A way of understanding speech by interpreting movements of the mouth and tongue. Lip-reading is often used by people who are deaf.

liquid paraffin A lubricant laxative drug obtained from petroleum. It can cause anal irritation, and prolonged use may impair the absorption of vitamins from the intestine into the blood. lisinopril An ACE inhibitor drug commonly used to treat hypertension. lisp A common speech disorder caused by protrusion of the tongue between the teeth so that the “s” sound is replaced by “th”. Sometimes the cause is a cleft palate (see cleft lip and palate). In most children, there is no physical defect and lisping disappears by the age of about 4. listeriosis An infection that is common in animals and may also affect humans. It is caused by the bacterium LISTERIA MONOCYTOGENES, which is widespread in the environment, especially in soil. Possible sources of human infection include soft cheese, ready-prepared coleslaw and salads, and improperly cooked meat.

In most adults, the only symptoms are fever and aching muscles. There may also be sore throat, conjunctivitis, diarrhoea, and abdominal pain. Pneumonia, septicaemia, and meningitis may develop in severe cases. However, listeriosis can be life-threatening, particularly in elderlypeople, those with reduced immunity, and newborn babies. In pregnant women, infection may cause a miscarriage.

The condition is diagnosed by blood tests and analysis of other body fluids, such as urine. Treatment is with antibiotic drugs, such as ampicillin.

Health Source: BMA Medical Dictionary
Author: The British Medical Association

Dyslexia

Dyslexia is di?culty in reading or learning to read. It is always accompanied by di?culty in writing, and particularly by diffculties in spelling. Reading diffculties might be due to various factors – for example, a general learning problem, bad teaching or understimulation, or a perceptive problem such as poor eyesight. Speci?c dyslexia (‘word blindness’), however, affects 4–8 per cent of otherwise normal children to some extent. It is three times more common in boys than in girls, and there is often a family history. The condition is sometimes missed and, when a child has di?culty with reading, dyslexia should be considered as a possible cause.

Support and advice may be obtained from the British Dyslexia Association.... dyslexia

Aphasia

Inability to speak caused by disease in or injury to the cerebral cortex in the left half of the BRAIN (in a right-handed person), affecting the generation and content of speech as well as the understanding of language; often accompanied by problems with reading and writing (see DYSPHASIA). Comprehension and expression of language occur in two zones of the cerebral cortex (the outer layer of the main part of the brain). They are known as Wernicke’s area (comprehension) and Broca’s area (speech formulation).... aphasia

Thermometer

An instrument for measuring a person’s body TEMPERATURE. A traditional clinical thermometer comprises a glass capillary tube sealed at one end with a MERCURY-?lled bulb at the other. The mercury expands (rises) and contracts (falls) according to the temperature of the bulb, which may be placed under the tongue or arm or in the rectum. Calibration is in degrees Celsius or Fahrenheit. Modern thermometers use an electric probe linked to a digital read-out display, providing an instant reading. Hospitals now have electronic devices that maintain constant monitoring of patients’ temperatures, pulse rates and blood pressure.... thermometer

Hypertension

Means high BLOOD PRESSURE (raised pressure of the circulating blood), but since there is a wide range of ‘normal’ blood pressure in the population, a precise level of pressure above which an individual is deemed hypertensive is arbitrary. (A healthy young adult would be expected to have a systolic pressure of around 120 mm Hg and a diastolic of 80 mm Hg, recorded as 120/80.) Hypertension is not a disease as such but a quantitative deviation from the norm. A person with a pressure higher than the average for his or her age group is usually symptomless – although sometimes such people may develop headaches. The identi?cation of people with hypertension is important because it is a signal that they will be more likely to have a STROKE or myocardial infarct (coronary thrombosis or heart attack) than someone whose pressure is in the ‘normal’ range. Preventive steps can then be taken to lessen the likelihood of their developing these potentially life-threatening conditions.

Blood pressure is measured using two values. The systolic pressure – the greater of the two – represents the pressure when blood is pumped from the left VENTRICLE of the heart into the AORTA. The diastolic pressure is the measurement when both ventricles relax between beats. The pressures are measured in millimetres (mm) of mercury (Hg). Despite the grey area between normal and raised blood pressure, the World Health Organisation (WHO) has de?ned hypertension as a blood pressure consistently greater than 160 mm Hg (systolic) and 95 mm Hg (diastolic). Young children have readings well below these, but blood pressure rises with age and a healthy person may well live symptom free with a systolic pressure above the WHO ?gure. A useful working de?nition of hypertension is the ?gure at which the bene?ts of treating the condition outweigh the risks and costs of the treatment.

Between 10 and 20 per cent of the adult population in the UK has hypertension, with more men than women affected. Incidence is highest in the middle-aged and elderly. Because most people with hypertension are symptomless, the condition is often ?rst identi?ed during a routine medical examination, otherwise a diagnosis is usually made when complications occur. Many people’s blood pressure rises when they are anxious or after exercise, so if someone’s pressure is above normal at the ?rst testing, it should be taken again after, say, 10 minutes’ rest, by which time the reading should have settled to the person’s regular level. BP measurements should then be taken on two subsequent occasions. If the pressure is still high, the cause needs to be determined: this is done using a combination of personal and family histories (hypertension can run in families), a physical examination and investigations, including an ECG and blood tests for renal disease.

Over 90 per cent of hypertensive people have no immediately identi?able cause for their condition. They are described as having essential hypertension. In those patients with an identi?able cause, the hypertension is described as secondary. Among the causes of secondary hypertension are:

Lifestyle factors such as smoking, alcohol, stress, excessive dietary salt and obesity.

Diseases of the KIDNEYS.

Pregnancy (ECLAMPSIA).

Various ENDOCRINE disorders – for example, PHAEOCHROMOCYTOMA, CUSHING’S DISEASE, ACROMEGALY, thyrotoxicosis (see under THYROID GLAND, DISEASES OF).

COARCTATION OF THE AORTA.

Drugs – for example, oestrogen-containing oral contraceptives (see under CONTRACEPTION), ANABOLIC STEROIDS, CORTICOSTEROIDS, NON-STEROIDAL ANTIINFLAMMATORY DRUGS (NSAIDS).

Treatment People with severe hypertension may need prompt admission to hospital for urgent investigation and treatment. Those with a mild to moderate rise in blood pressure for which no cause is identi?able should be advised to change their lifestyle: smokers should stop the habit, and those with high alcohol consumption should greatly reduce or stop their drinking. Obese people should reduce their food consumption, especially of animal fats, and take more exercise. Everyone with hypertension should follow a low-salt diet and take regular exercise. Patients should also be taught how to relax, which helps to reduce blood pressure and, if they have a stressful life, working patterns should be modi?ed if possible. If these lifestyle changes do not reduce a person’s blood pressure su?ciently, drugs to achieve this will be needed. A wide range of anti-hypertensive drugs are available on prescription.

A ?rst-line treatment is one of the THIAZIDES, e?ective at a low dosage and especially useful in the elderly. Beta blockers (see BETAADRENOCEPTOR-BLOCKING DRUGS), such as oxprenolol, acebutol or atenolol, are also ?rst-line treatments. ACE inhibitors (see ANGIOTENSIN-CONVERTING ENZYME (ACE) INHIBITORS) and CALCIUM-CHANNEL BLOCKERS can be used if the ?rst-line choices are not e?ective. The drug treatment of hypertension is complex, and sometimes various drugs or combinations of drugs have to be tried to ?nd what regimen is e?ective and suits the patient. Mild to moderate hypertension can usually be treated in general practice, but patients who do not respond or have complications will normally require specialist advice. Patients on anti-hypertensive treatments require regular monitoring, and, as treatment may be necessary for several years, particular attention should be paid to identifying sideeffects. Nevertheless, e?ective treatment of hypertension does enable affected individuals to live longer and more comfortable lives than would otherwise be the case. Older people with moderately raised blood pressure are often able to live with the condition, and treatment with anti-hypertensive drugs may produce symptoms of HYPOTENSION.

In summary, hypertension is a complex disorder, with di?erent patients responding di?erently to treatment. So the condition sometimes requires careful assessment before the most e?ective therapy for a particular individual is identi?ed, and continued monitoring of patients with the disorder is advisable.

Complications Untreated hypertension may eventually result in serious complications. People with high blood pressure have blood vessels with thickened, less ?exible walls, a narrowed LUMEN and convoluted shape. Sometimes arteries become rigid. ANEURYSM may develop and widespread ATHEROMA (fat deposits) is apparent in the arterial linings. Such changes adversely affect the blood supply to body tissues and organs and so damage their functioning. Patients suffer STROKE (haemorrhage from or thrombosis in the arteries of the BRAIN) and heart attacks (coronary thrombosis

– see HEART, DISEASES OF). Those with hypertension may suffer damage to the retina of the EYE and to the OPTIC DISC. Indeed, the diagnosis of hypertension is sometimes made during a routine eye test, when the doctor or optician notices changes in the retinal arteries or optic disc. Kidney function is often affected, with patients excreting protein and excessive salt in their urine. Occasionally someone with persistent hypertension may suffer an acceleration of damage to the blood vessels – a condition described as ‘malignant’ hypertension, and one requiring urgent hospital treatment.

Hypertension is a potentially dangerous disease because it develops into a cycle of self-perpetuating damage. Faulty blood vessels lead to high blood pressure which in turn aggravates the damage in the vessels and thus in the tissues and organs they supply with blood; this further raises the affected individual’s blood pressure and the pathological cycle continues.... hypertension

Blood Pressure

The cardio-vascular vessels may be compared with a central heating system in which a volume of water is forced through a network of pipes by a pump in a closed circuit, over and over again. Our heart and circulatory system operate in the same way.

Blood pressure is recorded by two readings on a sphygmomanometer with the aid of the traditional inflatable cuff. The top pressure is known as the systolic, the bottom as the diastolic. The systolic pressure occurs when the heart contracts, the diastolic when the heart relaxes and the volume of blood is at its lowest. A practitioner interprets the pressure of blood against the wall of the brachial artery in terms of millimetres.

In a healthy young person or middle-aged adult, average systolic pressure is 120, diastolic 80. They are recorded as 120/80. A pressure of 140/90 requires investigation while one of 160/95 is high and demands treatment. Average pressure at 50 is 135/80, over 65 – 165/85. Defined hypertension is a raised pressure on three consecutive readings.

The highest pressure peak is reached in the evening after a day’s work and the lowest, at night. Pressure may rise with stress when the heart responds by beating faster, or fall with physical or mental exhaustion when the heart slows down. Persistent high or low pressure is usually associated with other conditions which may require their own specific treatments: i.e. low – anaemia, high – kidney disease. See: HYPERTENSION. HYPOTENSION. ... blood pressure

Presbyopia

The progressive loss of the power of adjusting the eye (see accommodation) for near vision. The focusing power of the eyes weakens with age. Presbyopia is usually noticed around age 45 when the eyes cannot accommodate to read small print at a normal distance. Reading glasses with convex lenses are used to correct presbyopia.... presbyopia

Accommodation

The process by which the refractive power of the lens of the EYE is increased by constriction of the ciliary muscle, producing an increased thickness and curvature of the lens. Rays of light from an object further than 6 metres away are parallel on reaching the eye. These rays are brought to a focus on the retina, mainly by the cornea. If the eye is now directed at an object

closer than 6 metres away, the rays of light from this near object will be diverging by the time they reach the eye. In order to focus these diverging beams of light, the refracting power of the lens must increase. In other words the lens must accommodate.

The lens loses its elasticity with age, and thus becomes less spherical when tension in the zonule relaxes. This results in an increased longsightedness (presbyopia) requiring reading glasses for correction. (See AGEING.)... accommodation

Artichoke, Globe

Nutritional Profile Energy value (calories per serving): Low Protein: Moderate Fat: Low Saturated fat: Low Cholesterol: None Carbohydrates: High Fiber: Low Sodium: Moderate to high Major vitamin contribution: Vitamin C Major mineral contribution: Potassium

About the Nutrients in This Food Globe artichokes are prickly plants with partly edible leaves enclosing a tasty “heart.” Their most important nutrients are vitamin C and iron. One medium boiled artichoke has 10.3 g dietary fiber, 8.9 mg vita- min C (12 percent of the R DA for a woman, 10 percent of the R DA for a man), and 0.7 mg iron (4 percent of the R DA for a woman, 9 percent of the R DA for a man). One-half cup artichoke hearts has 7.2 g dietary fiber, 6.2 mg vitamin C (8 percent of the R DA for a woman, 7 percent of the R DA for a man), and 0.5 mg iron (3 percent of the R DA for a woman, 6 percent of the R DA for a man). Raw globe artichokes contain an enzyme that interferes with protein digestion; cooking inactivates the enzyme.

The Most Nutritious Way to Serve This Food Cooked.

Diets That May Restrict or Exclude This Food * * *

Buying This Food Look for: Compact vegetables, heavy for their size. The leaves should be tightly closed, but the color changes with the season—bright green in the spring, olive green or bronze in the winter if they have been exposed to frost. Avoid: Artichokes with yellowed leaves, which indicate the artichoke is aging (the chloro- phyll in its leaves has faded so the yellow carotenes underneath show through).

Storing This Food Do refrigerate fresh globe artichokes in plastic bags. Do refrigerate cooked globe artichokes in a covered container if you plan to hold them longer than a day or two.

Preparing This Food Cut off the stem. Trim the tough outer leaves. Then plunge the artichoke, upside down, into a bowl of cold water to flush out debris. To remove the core, put the artichoke upside down on a cutting board and cut out the center. Slicing into the base of the artichoke rips cell walls and releases polyphenoloxidase, an enzyme that converts phenols in the vegetable to brown compounds that darken the “heart” of the globe. To slow the reaction, paint the cut surface with a solution of lemon juice or vinegar and water.

What Happens When You Cook This Food Chlorophyll, the green plant pigment, is sensitive to acids. When you heat a globe artichoke, the chlorophyll in its green leaves reacts with acids in the artichoke or in the cooking water, forming brown pheophytin. The pheophytin, plus yellow carotenes in the leaves, can turn a cooked artichoke’s leaves bronze. To prevent this reaction, cook the artichoke very quickly so there is no time for the chlorophyll to react with the acid, or cook it in lots of water to dilute the acids, or cook it with the lid off the pot so that the volatile acids can float off into the air.

How Other Kinds of Processing Affect This Food Canning. Globe artichoke hearts packed in brine are higher in sodium than fresh arti- chokes. Artichoke hearts packed in oil are much higher in fat. Freezing. Frozen artichoke hearts are comparable in nutritional value to fresh ones.

Medical Uses and/or Benefits Anti-inflammatory action. In 2006, a report in the Journal of the Pharmaceutical Society of Japan suggested that cynarin might be beneficial in lowering blood levels of cholesterol and that cynaropicrin, a form of cynarin found in artichoke leaves, might act as an anti-inflamma- tory agent, protecting the skin from sun damage, improving liver function, and reducing the effects of stress-related gastritis. Reduced levels of cholesterol. In 2008, researchers at the University of Reading (United King- dom) published a report in the journal Phytomedicine detailing the results of a 150-person study suggesting that an over-the-counter herbal supplement containing extract of globe arti- choke leaf lowers cholesterol in healthy people with moderately raised cholesterol readings. In the study, 75 volunteers were given 1,280 mg of the herbal supplement each day for 12 weeks; a control group got a placebo (a look-alike pill without the herbal supplement). At the end of the trial, those who took the artichoke leaf extract experienced an average 4.2 percent decrease in cholesterol levels, a result the researchers deemed “modest but significant.”

Adverse Effects Associated with This Food Contact dermatitis. Globe artichokes contain essential oils that may cause contact dermati- tis in sensitive people. Alterations in the sense of taste. Globe artichokes contain cynarin, a sweet tasting chemical that dissolves in water (including the saliva in your mouth) to sweeten the flavor of anything you eat next.

Food/Drug Interactions False-positive test for occult blood in the stool. The guaiac slide test for hidden blood in feces relies on alphaguaiaconic acid, a chemical that turns blue in the presence of blood. Arti- chokes contain peroxidase, a natural chemical that also turns alphaguaiaconic acid blue and may produce a positive test in people who do not have blood in the stool.... artichoke, globe

Bifocal Lens

A spectacle lens in which the upper part is shaped to assist distant vision and the lower part is for close work such as reading.... bifocal lens

Blueberries

(Huckleberries)

Nutritional Profile Energy value (calories per serving): Low Protein: Low Fat: Low Saturated fat: Low Cholesterol: None Carbohydrates: High Fiber: Moderate Sodium: Low Major vitamin contribution: Vitamin C Major mineral contribution: Calcium

About the Nutrients in This Food Blueberries have some protein and a little fat. They have no starch but do contain sugars and dietary fiber—primarily pectin, which dissolves as the fruit matures—and lignin in the seeds. (The difference between blueber- ries and huckleberries is the size of their seeds; blueberries have smaller ones than huckleberries.) One-half cup fresh blueberries has 1.5 g dietary fiber and 9.5 mg. vitamin C (13 percent of the R DA for a woman, 11 percent of the R DA for a man).

The Most Nutritious Way to Serve This Food Fresh, raw, or lightly cooked.

Buying This Food Look for: Plump, firm dark-blue berries. The whitish color on the ber- ries is a natural protective coating. Avoid: Baskets of berries with juice stains or liquid leaking out of the berries. The stains and leaks are signs that there are crushed (and possibly moldy) berries inside.

Storing This Food Cover berries and refrigerate them. Then use them in a day or two. Do not wash berries before storing. The moisture increases the chance that they will mold in the refrigerator. Also, handling the berries can damage them, tearing cells and releas- ing enzymes that will destroy vitamins. Do not store blueberries in metal containers. The anthocyanin pigments in the berries can combine with metal ions to form dark, unattractive pigment/metal compounds that stain the containers and the berries.

Preparing This Food R inse the berries under cool running water, then drain them and pick them over carefully to remove all stems, leaves, and hard (immature) or soft (over-ripe) berries.

What Happens When You Cook This Food Cooking destroys some of the vitamin C in fresh blueberries and lets water-soluble B vitamins leach out. Cooked berries are likely to be mushy because heat dissolves the pectin inside. Blueberries may also change color when cooked. The berries are colored with blue anthocyanin pigments. Ordinarily, anthocyanin-pigmented fruits and vegetables turn red- dish in acids (lemon juice, vinegar) and deeper blue in bases (baking soda). But blueberries also contain yellow pigments (anthoxanthins). In a basic (alkaline) environments, as in a batter with too much baking soda, the yellow and blue pigments will combine, turning the blueberries greenish blue. Adding lemon juice to a blueberry pie stabilizes these pigments; it is a practical way to keep the berries a deep, dark reddish blue.

How Other Kinds of Processing Affect This Food Canning and freezing. The intense heat used in canning the fruit or in blanching it before freezing reduces the vitamin C content of blueberries by half.

Medical Uses and/or Benefits Anticancer activity. According to the U.S. Department of Agriculture, wild blueberries rank first among all fruits in antioxidant content; cultivated blueberries (the ones sold in most food markets) rank second. Antioxidants are natural chemicals that inactivate free radicals, molecule fragments that can link together to form cancer-causing compounds. Several ani- mal studies attest to the ability of blueberries to inhibit the growth of specific cancers. For example, in 2005, scientists at the University of Georgia reported in the journal Food Research International that blueberry extracts inhibited the growth of liver cancer cells in laboratory settings. The following year, researchers at Rutgers University (in New Jersey) delivered data to the national meeting of the American Chemical Society from a study in which laboratory rats fed a diet supplemented with pterostilbene, another compound extracted from blueber- ries, had 57 percent fewer precancerous lesions in the colon than rats whose diet did not contain the supplement. The findings, however, have not been confirmed in humans. Enhanced memory function. In 2008, British researchers at the schools of Food Biosciences and Psychology at the University of Reading and the Institute of Biomedical and Clinical Sciences at the Peninsula Medical School (England) reported that adding blueberries to one’s normal diet appears to improve both long-term and short-term memory, perhaps because anthocyanins and flavonoids (water-soluble pigments in the berries) activate signals in the hippocampus, a part of the brain that controls learning and memory. If confirmed, the data would support the role played by diet in maintaining memory and brain function. Urinary antiseptic. A 1991 study at the Weizmann Institute of Science (Israel) suggests that blueberries, like cr anber r ies, contain a compound that inhibits the ability of Escherichia coli, a bacteria commonly linked to urinary infections, to stick to the wall of the bladder. If it cannot cling to cell walls, the bacteria will not cause an infection. This discovery lends some support to folk medicine, but how the berries work, how well they work, or in what “dos- ages” remains to be proven.

Adverse Effects Associated with This Food Allergic reaction. Hives and angiodemea (swelling of the face, lips, and eyes) are common allergic responses to berries, virtually all of which have been reported to trigger these reac- tions. According to the Merck Manual, berries are one of the 12 foods most likely to trigger classic food allergy symptoms. The others are chocolate, corn, eggs, fish, legumes (peas, lima beans, peanuts, soybeans), milk, nuts, peaches, pork, shellfish, and wheat (see wheat cer ea ls).... blueberries

Diastolic

The lower number of a blood pressure reading signifying the myocardial and arterial relaxation between pump strokes. Too close to the higher number (systolic) usually signifies inadequate relaxation of the heart and arteries between heartbeats.... diastolic

Diastolic Pressure

The pressure exerted by the blood against the arterial wall during DIASTOLE. This is the lowest blood pressure in the cardiac cycle. A normal reading of diastolic pressure in a healthy adult at rest is 70 mm Hg. (See HEART.)... diastolic pressure

Eye, Disorders Of

Arcus senilis The white ring or crescent which tends to form at the edge of the cornea with age. It is uncommon in the young, when it may be associated with high levels of blood lipids (see LIPID).

Astigmatism (See ASTIGMATISM.)

Blepharitis A chronic in?ammation of the lid margins. SEBORRHOEA and staphylococcal infection are likely contributors. The eyes are typically intermittently red, sore and gritty over months or years. Treatment is di?cult and may fail. Measures to reduce debris on the lid margins, intermittent courses of topical antibiotics, steroids or systemic antibiotics may help the sufferer.

Blepharospasm Involuntary closure of the eye. This may accompany irritation but may also occur without an apparent cause. It may be severe enough to interfere with vision. Treatment involves removing the source of irritation, if present. Severe and persistent cases may respond to injection of Botulinum toxin into the orbicularis muscle.

Cataract A term used to describe any opacity in the lens of the eye, from the smallest spot to total opaqueness. The prevalence of cataracts is age-related: 65 per cent of individuals in their sixth decade have some degree of lens opacity, while all those over 80 are affected. Cataracts are the most important cause of blindness worldwide. Symptoms will depend on whether one or both eyes are affected, as well as the position and density of the cataract(s). If only one eye is developing a cataract, it may be some time before the person notices it, though reading may be affected. Some people with cataracts become shortsighted, which in older people may paradoxically ‘improve’ their ability to read. Bright light may worsen vision in those with cataracts.

The extent of visual impairment depends on the nature of the cataracts, and the ?rst symptoms noticed by patients include di?culty in recognising faces and in reading, while problems watching television or driving, especially at night, are pointers to the condition. Cataracts are common but are not the only cause of deteriorating vision. Patients with cataracts should be able to point to the position of a light and their pupillary reactions should be normal. If a bright light is shone on the eye, the lens may appear brown or, in advanced cataracts, white (see diagram).

While increasing age is the commonest cause of cataract in the UK, patients with DIABETES MELLITUS, UVEITIS and a history of injury to the eye can also develop the disorder. Prolonged STEROID treatment can result in cataracts. Children may develop cataracts, and in them the condition is much more serious as vision may be irreversibly impaired because development of the brain’s ability to interpret visual signals is hindered. This may happen even if the cataracts are removed, so early referral for treatment is essential. One of the physical signs which doctors look for when they suspect cataract in adults as well as in children is the ‘red re?ex’. This is observable when an ophthalmoscopic examination of the eye is made (see OPHTHALMOSCOPE). Identi?cation of this red re?ex (a re?ection of light from the red surface of the retina –see EYE) is a key diagnostic sign in children, especially young ones.

There is no e?ective medical treatment for established cataracts. Surgery is necessary and the decision when to operate depends mainly on how the cataract(s) affect(s) the patient’s vision. Nowadays, surgery can be done at any time with limited risk. Most patients with a vision of 6/18 – 6/10 is the minimum standard for driving – or worse in both eyes should

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bene?t from surgery, though elderly people may tolerate visual acuity of 6/18 or worse, so surgery must be tailored to the individual’s needs. Younger people with a cataract will have more demanding visual requirements and so may opt for an ‘earlier’ operation. Most cataract surgery in Britain is now done under local anaesthetic and uses the ‘phaco-emulsi?cation’ method. A small hole is made in the anterior capsule of the lens after which the hard lens nucleus is liqui?ed ultrasonically. A replacement lens is inserted into the empty lens bag (see diagram). Patients usually return to their normal activities within a few days of the operation. A recent development under test in the USA for children requiring cataract operations is an intra-ocular ?exible implant whose magnifying power can be altered as a child develops, thus precluding the need for a series of corrective operations as happens now.

Chalazion A ?rm lump in the eyelid relating to a blocked meibomian gland, felt deep within the lid. Treatment is not always necessary; a proportion spontaneously resolve. There can be associated infection when the lid becomes red and painful requiring antibiotic treatment. If troublesome, the chalazion can be incised under local anaesthetic.

Conjunctivitis In?ammation of the conjunctiva (see EYE) which may affect one or both eyes. Typically the eye is red, itchy, sticky and gritty but is not usually painful. Redness is not always present. Conjunctivitis can occasionally be painful, particularly if there is an associated keratitis (see below) – for example, adenovirus infection, herpetic infection.

The cause can be infective (bacteria, viruses or CHLAMYDIA), chemical (e.g. acids, alkalis) or allergic (e.g. in hay fever). Conjunctivitis may also be caused by contact lenses, and preservatives or even the drugs in eye drops may cause conjunctival in?ammation. Conjunctivitis may addtionally occur in association with other illnesses – for example, upper-respiratory-tract infection, Stevens-Johnson syndrome (see ERYTHEMA – erythema multiforme) or REITER’S SYNDROME. The treatment depends on the cause. In many patients acute conjunctivitis is self-limiting.

Dacryocystitis In?ammation of the lacrimal sac. This may present acutely as a red, painful swelling between the nose and the lower lid. An abscess may form which points through the skin and which may need to be drained by incision. Systemic antibiotics may be necessary. Chronic dacryocystitis may occur with recurrent discharge from the openings of the tear ducts and recurrent swelling of the lacrimal sac. Obstruction of the tear duct is accompanied by watering of the eye. If the symptoms are troublesome, the patient’s tear passageways need to be surgically reconstructed.

Ectropion The lid margin is everted – usually the lower lid. Ectropion is most commonly associated with ageing, when the tissues of the lid become lax. It can also be caused by shortening of the skin of the lids such as happens with scarring or mechanical factors – for example, a tumour pulling the skin of the lower lid downwards. Ectropion tends to cause watering and an unsightly appearance. The treatment is surgical.

Entropion The lid margin is inverted – usually the lower lid. Entropion is most commonly associated with ageing, when the tissues of the lid become lax. It can also be caused by shortening of the inner surfaces of the lids due to scarring – for example, TRACHOMA or chemical burns. The inwardly directed lashes cause irritation and can abrade the cornea. The treatment is surgical.

Episcleritis In?ammation of the EPISCLERA. There is usually no apparent cause. The in?ammation may be di?use or localised and may affect one or both eyes. It sometimes recurs. The affected area is usually red and moderately painful. Episcleritis is generally not thought to be as painful as scleritis and does not lead to the same complications. Treatment is generally directed at improving the patient’s symptoms. The in?ammation may respond to NON-STEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDS) or topical CORTICOSTEROIDS.

Errors of refraction (Ametropia.) These will occur when the focusing power of the lens and cornea does not match the length of the eye, so that rays of light parallel to the visual axis are not focused at the fovea centralis (see EYE). There are three types of refractive error: HYPERMETROPIA or long-sightedness. The refractive power of the eye is too weak, or the eye is too short so that rays of light are brought to a focus at a point behind the retina. Longsighted people can see well in the distance but generally require glasses with convex lenses for reading. Uncorrected long sight can lead to headaches and intermittent blurring of vision following prolonged close work (i.e. eye strain). As a result of ageing, the eye becomes gradually long-sighted, resulting in many people needing reading glasses in later life: this normal process is known as presbyopia. A particular form of long-sightedness occurs after cataract extraction (see above). MYOPIA(Short sight or near sight.) Rays of light are brought to a focus in front of the retina because the refractive power of the eye is too great or the eye is too short. Short-sighted people can see close to but need spectacles with concave lenses in order to see in the distance. ASTIGMATISMThe refractive power of the eye is not the same in each meridian. Some rays of light may be focused in front of the retina while others are focused on or behind the retina. Astigmatism can accompany hypermetropia or myopia. It may be corrected by cylindrical lenses: these consist of a slice from the side of a cylinder (i.e. curved in one meridian and ?at in the meridian at right-angles to it).

Keratitis In?ammation of the cornea in response to a variety of insults – viral, bacterial, chemical, radiation, or mechanical trauma. Keratitis may be super?cial or involve the deeper layers, the latter being generally more serious. The eye is usually red, painful and photophobic. Treatment is directed at the cause.

Nystagmus Involuntary rhythmic oscillation of one or both eyes. There are several causes including nervous disorders, vestibular disorders, eye disorders and certain drugs including alcohol.

Ophthalmia In?ammation of the eye, especially the conjunctiva (see conjunctivitis, above). Ophthalmia neonatorum is a type of conjunctivitis that occurs in newborn babies. They catch the disease when passing through an infected birth canal during their mother’s labour (see PREGNANCY AND LABOUR). CHLAMYDIA and GONORRHOEA are the two most common infections. Treatment is e?ective with antibiotics: untreated, the infection may cause permanent eye damage.

Pinguecula A benign degenerative change in the connective tissue at the nasal or temporal limbus (see EYE). This is visible as a small, ?attened, yellow-white lump adjacent to the cornea.

Pterygium Overgrowth of the conjunctival tissues at the limbus on to the cornea (see EYE). This usually occurs on the nasal side and is associated with exposure to sunlight. The pterygium is surgically removed for cosmetic reasons or if it is thought to be advancing towards the visual axis.

Ptosis Drooping of the upper lid. May occur because of a defect in the muscles which raise the lid (levator complex), sometimes the result of ageing or trauma. Other causes include HORNER’S SYNDROME, third cranial nerve PALSY, MYASTHENIA GRAVIS, and DYSTROPHIA MYOTONICA. The cause needs to be determined and treated if possible. The treatment for a severely drooping lid is surgical, but other measures can be used to prop up the lid with varying success.

Retina, disorders of The retina can be damaged by disease that affects the retina alone, or by diseases affecting the whole body.

Retinopathy is a term used to denote an abnormality of the retina without specifying a cause. Some retinal disorders are discussed below. DIABETIC RETINOPATHY Retinal disease occurring in patients with DIABETES MELLITUS. It is the commonest cause of blind registration in Great Britain of people between the ages of 20 and 65. Diabetic retinopathy can be divided into several types. The two main causes of blindness are those that follow: ?rst, development of new blood vessels from the retina, with resultant complications and, second, those following ‘water logging’ (oedema) of the macula. Treatment is by maintaining rigid control of blood-sugar levels combined with laser treatment for certain forms of the disease – in particular to get rid of new blood vessels. HYPERTENSIVE RETINOPATHY Retinal disease secondary to the development of high blood pressure. Treatment involves control of the blood pressure (see HYPERTENSION). SICKLE CELL RETINOPATHY People with sickle cell disease (see under ANAEYIA) can develop a number of retinal problems including new blood vessels from the retina. RETINOPATHY OF PREMATURITY (ROP) Previously called retrolental ?broplasia (RLF), this is a disorder affecting low-birth-weight premature babies exposed to oxygen. Essentially, new blood vessels develop which cause extensive traction on the retina with resultant retinal detachment and poor vision. RETINAL ARTERY OCCLUSION; RETINAL VEIN OCCLUSION These result in damage to those areas of retina supplied by the affected blood vessel: the blood vessels become blocked. If the peripheral retina is damaged the patient may be completely symptom-free, although areas of blindness may be detected on examination of ?eld of vision. If the macula is involved, visual loss may be sudden, profound and permanent. There is no e?ective treatment once visual loss has occurred. SENILE MACULAR DEGENERATION (‘Senile’ indicates age of onset and has no bearing on mental state.) This is the leading cause of blindness in the elderly in the western world. The average age of onset is 65 years. Patients initially notice a disturbance of their vision which gradually progresses over months or years. They lose the ability to recognise ?ne detail; for example, they cannot read ?ne print, sew, or recognise people’s faces. They always retain the ability to recognise large objects such as doors and chairs, and are therefore able to get around and about reasonably well. There is no e?ective treatment in the majority of cases. RETINITIS PIGMENTOSAA group of rare, inherited diseases characterised by the development of night blindness and tunnel vision. Symptoms start in childhood and are progressive. Many patients retain good visual acuity, although their peripheral vision is limited. One of the characteristic ?ndings on examination is collections of pigment in the retina which have a characteristic shape and are therefore known as ‘bone spicules’. There is no e?ective treatment. RETINAL DETACHMENTusually occurs due to the development of a hole in the retina. Holes can occur as a result of degeneration of the retina, traction on the retina by the vitreous, or injury. Fluid from the vitreous passes through the hole causing a split within the retina; the inner part of the retina becomes detached from the outer part, the latter remaining in contact with the choroid. Detached retina loses its ability to detect light, with consequent impairment of vision. Retinal detachments are more common in the short-sighted, in the elderly or following cataract extraction. Symptoms include spots before the eyes (?oaters), ?ashing lights and a shadow over the eye with progressive loss of vision. Treatment by laser is very e?ective if caught early, at the stage when a hole has developed in the retina but before the retina has become detached. The edges of the hole can be ‘spot welded’ to the underlying choroid. Once a detachment has occurred, laser therapy cannot be used; the retina has to be repositioned. This is usually done by indenting the wall of the eye from the outside to meet the retina, then making the retina stick to the wall of the eye by inducing in?ammation in the wall (by freezing it). The outcome of surgery depends largely on the extent of the detachment and its duration. Complicated forms of detachment can occur due to diabetic eye disease, injury or tumour. Each requires a specialised form of treatment.

Scleritis In?ammation of the sclera (see EYE). This can be localised or di?use, can affect the anterior or the posterior sclera, and can affect one or both eyes. The affected eye is usually red and painful. Scleritis can lead to thinning and even perforation of the sclera, sometimes with little sign of in?ammation. Posterior scleritis in particular may cause impaired vision and require emergency treatment. There is often no apparent cause, but there are some associated conditions – for example, RHEUMATOID ARTHRITIS, GOUT, and an autoimmune disease affecting the nasal passages and lungs called Wegener’s granulomatosis. Treatment depends on severity but may involve NON-STEROIDAL ANTI-INFLAMMATORY DRUGS (NSAIDS), topical CORTICOSTEROIDS or systemic immunosuppressive drugs.

Stye Infection of a lash follicle. This presents as a painful small red lump at the lid margin. It often resolves spontaneously but may require antibiotic treatment if it persists or recurs.

Sub-conjunctival haemorrhage Haemorrhage between the conjunctiva and the underlying episclera. It is painless. There is usually no apparent cause and it resolves spontaneously.

Trichiasis Inward misdirection of the lashes. Trichiasis occurs due to in?ammation of or trauma to the lid margin. Treatment involves removal of the patient’s lashes. Regrowth may be prevented by electrolysis, by CRYOTHERAPY to the lid margin, or by surgery.

For the subject of arti?cial eyes, see under PROSTHESIS; also GLAUCOMA, SQUINT and UVEITIS.... eye, disorders of

Liriene

(French) One who enjoys reading aloud

Lirienne, Liriena, Lirienna, Lirien, Lirienn... liriene

Narcolepsy

A chronic neurologic condition characterized by reoccurring and inexplicable drowsiness and sleep. There is no organic cause and no seeming changes in EEG readings.... narcolepsy

Dysphasia

Dysphasia is the term used to describe the dif?culties in understanding language and in self-expression, most frequently after STROKE or other brain damage. When there is a total loss in the ability to communicate through speech or writing, it is known as global aphasia. Many more individuals have a partial understanding of what is said to them; they are also able to put their own thoughts into words to some extent. The general term for this less severe condition is dysphasia. Individuals vary widely, but in general there are two main types of dysphasia. Some people may have a good understanding of spoken language but have di?culty in self-expression; this is called expressive or motor dysphasia. Others may have a very poor ability to understand speech, but will have a considerable spoken output consisting of jargon words; this is known as receptive or sensory dysphasia. Similar diffculties may occur with reading, and this is called DYSLEXIA (a term more commonly encountered in the di?erent context of children’s reading disability). Adults who have suffered a stroke or another form of brain damage may also have di?culty in writing, or dysgraphia. The speech therapist can assess the ?ner diagnostic pointsand help them adjust to the effects of the stroke on communication. (See SPEECH THERAPY.)

Dysphasia may come on suddenly and last only for a few hours or days, being due to a temporary block in the circulation of blood to the brain. The effects may be permanent, but although the individual may have di?culty in understanding language and expressing themselves, they will be quite aware of their surroundings and may be very frustrated by their inability to communicate with others.

Further information may be obtained from Speakability.... dysphasia

Hypotension

Low blood pressure (see HYPERTENSION for raised blood pressure). Some healthy individuals with a normal cardiovascular system have a permanently low arterial blood pressure for their age. What blood-pressure reading constitutes hypotension is arguable, but a healthy young person with ?gures below 100 mm Hg systolic and 65 mm Hg diastolic could be described as hypotensive. For a healthy 60 year old, comparative ?gures might be 120/80. The most common type of hypotension is called postural, with symptoms occurring when a person suddenly stands up, particularly after a period of rest or a hot bath. It results from the muscular tone of blood vessels becoming relaxed and being unable to respond quickly enough to the changing posture, the consequence being a temporary shortage of arterial blood to the brain and organs in the chest. Symptoms of dizziness, occasionally fainting, and nausea occur. Older people are especially vulnerable and may fall as a result of the sudden hypotension. Some drugs – anti-hypertensives and antidepressant ones – cause hypotension. People with DIABETES MELLITUS occasionally develop hypotension because of nerve damage that affects the re?ex impulses controlling blood pressure. Any severe injury or burn that results in serious loss of blood or body ?uid will cause hypotension and SHOCK. Myocardial infarction (see HEART, DISEASES OF) or failure of the ADRENAL GLANDS can cause hypotension and shock. A severe emotional event that causes shock may also result in hypotension and fainting.

Hypotension in healthy people does not require treatment, although affected individuals should be advised not to stand up suddenly or get out of a bath quickly. Someone who faints as a result of a hypotensive incident should be laid down for a few minutes to allow the circulation to return to normal. Hypotension resulting from burns, blood loss, heart attack or adrenal failure (shock) requires medical attention for the causative condition.... hypotension

Rapid-eye-movement (rem) Sleep

This is characterised by the presence of rapid eye movements and a reduction in muscle tone. Cerebral cortical activity is prominent and its blood ?ow increased. This activity is, however, di?erent from wakefulness and may cause irregular movements of the body as well as of the eyes. Most dreams occur in REM sleep: these may represent a process of reorganising mental associations after the period of wakefulness. The analysis of the content of dreams has been subject to a variety of interpretations, but no consensus view has evolved.

Physiological changes, such as a fall in temperature and blood pressure, take place just before sleep and continue during the early stages of NREM sleep. There is an intrinsic rhythm of sleep which in most subjects has a periodicity of around 25 hours. This can be modi?ed by external factors to bring it into line with the 24-hour day. Two peaks of a tendency to sleep have been identi?ed, and these usually occur between around 14.00–18.00 hours, and 02.00–06.00 hours. There are, however, di?erences according to age, in that, for instance, infants sleep for most of the 24 hours; during adolescence there is also an increase in the duration of sleep. Sleep requirements fall later in life, but there are wide genetic di?erences in the amount of sleep that people require and also the time at which they fall asleep most readily.

The internal clock can be disturbed by a variety of external factors which include irregular sleeping habits due, for instance, to shift work or jet lag. Sleep is also more likely to occur after physical exertion, reading and social activity. The duration and intensity of exposure to light can also modify sleep profoundly. Light promotes wakefulness and is the main factor that adjusts the 25-hour internal rhythm to the 24hour daily cycle. Neural connections from the retina of the EYE act on an area in the brain called the supra-chiasmatic nucleus which stimulates the pineal gland which produces MELATONIN. This is thought to trigger the range of neurological and metabolic processes that characterise sleep.... rapid-eye-movement (rem) sleep

Speech Disorders

These may be of physical or psychological origin – or a combination of both. Di?culties may arise at various stages of development: due to problems during pregnancy; at birth; caused by childhood illnesses; or as a result of delayed development. Congenital defects such as CLEFT PALATE or lip may make speech unintelligible until major surgery is performed, thus discouraging talking and delaying development. Recurrent ear infections may make hearing dif?cult; the child’s experience of speech is thus limited, with similar results. Childhood DYSPHASIA occurs if the language-development area of the BRAIN develops abnormally; specialist education and SPEECH THERAPY may then be required.

Dumbness is the inability to pronounce the sounds that make up words. DEAFNESS is the most important cause, being due to a congenital brain defect, or acquired brain disease, such as tertiary SYPHILIS. When hearing is normal or only mildly impaired, dumbness may be due to a structural defect such as tongue-tie or enlarged tonsils and adenoids, or to ine?cient voice control, resulting in lisping or lalling. Increased tension is a common cause of STAMMERING; speech disorders may occasionally be of psychological origin.

Normal speech may be lost in adulthood as a result of a STROKE or head injury. Excessive use of the voice may be an occupational hazard; and throat cancer may require a LARYNGECTOMY, with subsequent help in communication. Severe psychiatric disturbance may be accompanied by impaired social and communication skills. (See also VOICE AND SPEECH.)

Treatment The underlying cause of the problem should be diagnosed as early as possible; psychological and other specialist investigations should be carried out as required, and any physical defect should be repaired. People who are deaf and unable to speak should start training in lip-reading as soon as possible, and special educational methods aimed at acquiring a modulated voice should similarly be started in early childhood – provided by the local authority, and continued as required. Various types of speech therapy or PSYCHOTHERAPY may be appropriate, alone or in conjunction with other treatments, and often the ?nal result may be highly satisfying, with a good command of language and speech being obtained.

Help and advice may be obtained from AFASIC (Unlocking Speech and Language).... speech disorders

Sphygmomanometer

The traditional device for measuring blood pressure in clinical practice, devised by Riva-Rocci and Korotko? about a century ago. Measurement depends on accurate transmission and interpretation of the pulse wave to an artery. The sphygmomanometer is of two types, mercury and aneroid. The former is more accurate. Both have some features in common – an in?ation-de?ation system, an occluding bladder encased in a cu?, and the use of AUSCULTATION with a STETHOSCOPE. The mercury sphygmomanometer consists of a pneumatic armlet which is connected via a rubber tube with an air-pressure pump and a measuring gauge comprising a glass column containing mercury. The armlet is bound around the upper arm and pumped up su?ciently to obliterate the pulse felt at the wrist or heard by auscultation of the artery at the bend of the elbow. The pressure, measured in millimetres of mercury (mm Hg), registered at this point on the gauge is regarded as the pressure of the blood at each heartbeat (ventricular contraction). This is called the systolic pressure. The cu? is then slowly de?ated by releasing the valve on the air pump and the pressure at which the sound heard in the artery suddenly changes its character marks the diastolic pressure. Aneroid sphygmomanometers register pressure through an intricate bellows and lever system which is more susceptible than the mercury type to the bumps and jolts of everyday use which reduce its inaccuracy.

While mercury sphygmomanometers are simple, accurate and easily serviced, there is concern about possible mercury toxicity for users, those servicing the devices and the environment. Use of them has already been banned in some European hospitals. Although it may be a few years before they are widely replaced, automated blood-pressure-measuring devices will increasingly be in routine use. A wide variety of ambulatory blood-pressuremeasuring devices are already available and may be ?tted in general practice or hospital settings, where the patient is advised on the technique. Blood-pressure readings can be taken half-hourly – or more often, if required – with little disturbance of the patient’s daily activities or sleep. (See also BLOOD PRESSURE; HYPERTENSION.)... sphygmomanometer

Temperature

Body temperature is the result of a balance of heat-generating forces, chie?y METABOLISM and muscular activity, and heat-loss, mainly from blood circulation through and evaporation from the skin and lungs. The physiological process of homeostasis – a neurological and hormonal feedback mechanism – maintains the healthy person’s body at the correct temperature. Disturbance of temperature, as in disease, may be caused by impairment of any of these bodily functions, or by malfunction of the controlling centre in the brain.

In humans the ‘normal’ temperature is around 37 °C (98·4 °F). It may rise as high as 43 °C or fall to 32 °C in various conditions, but the risk to life is only serious above 41 °C or below 35 °C.

Fall in temperature may accompany major loss of blood, starvation, and the state of collapse (see SHOCK) which may occur in severe FEVER and other acute conditions. Certain chronic diseases, notably hypothyroidism (see THYROID GLAND, DISEASES OF), are generally accompanied by a subnormal temperature. Increased temperature is a characteristic of many acute diseases, particularly infections; indeed, many diseases have a characteristic pattern that enables a provisional diagnosis to be made or acts as a warning of possible complications. In most cases the temperature gradually abates as the patient recovers, but in others, such as PNEUMONIA and TYPHUS FEVER, the untreated disease ends rapidly by a CRISIS in which the temperature falls, perspiration breaks out, the pulse rate falls, and breathing becomes quieter. This crisis is often preceded by an increase in symptoms, including an epicritical rise in temperature.

Body temperature is usually measured on the Celsius scale, on a thermometer reading from 35 °C to 43·3 °C. Measurement may be taken in the mouth (under the tongue), in the armpit, the external ear canal or (occasionally in infants) in the rectum. (See also THERMOMETER.)

Treatment Abnormally low temperatures may be treated by application of external heat, or reduction of heat loss from the body surface. High temperature may be treated in various ways, apart from the primary treatment of the underlying condition. Treatment of hyperthermia or hypothermia should ensure a gradual return to normal temperature (see ANTIPYRETICS.... temperature

Alexia

Word blindness; inability to recognize and name written words. Alexia is caused by damage to part of the cerebrum (the main mass of the brain) by a stroke, for example. It severely disrupts

the reading ability of a person who was previously literate. (See also dyslexia.)... alexia

Warfarin

An anticoagulant (see ANTICOAGULANTS), usually given by mouth on a daily basis. The initial dose depends upon the PROTHROMBIN or coagulation time; this should be determined before starting treatment, and then at regular intervals during treatment. It is indicated for the prophylaxis of embolisation (see EMBOLISM) in rheumatic heart disease and atrial ?brillation (see HEART, DISEASES OF); after prosthetic heart-valve insertion; prophylaxis and treatment of venous thrombosis and PULMONARY EMBOLISM; and TRANSIENT ISCHAEMIC ATTACKS OR EPISODES (TIA, TIE). When given in tablet form, its maximum e?ect generally occurs within about 36 hours, wearing o? within 48 hours. Special caution is appropriate in patients with disease of the liver or kidneys or who have had recent surgery. Warfarin is contra-indicated throughout pregnancy (especially the ?rst and third trimesters), and in cases of PEPTIC ULCER, severe HYPERTENSION and bacterial ENDOCARDITIS. The most important adverse e?ect is HAEMORRHAGE. Other reported side-effects include HYPERSENSITIVITY, rash, ALOPECIA, diarrhoea, unexplained drop in HAEMATOCRIT readings, purple toes, skin NECROSIS, JAUNDICE, liver dysfunction, nausea, vomiting and pancreatitis (see PANCREAS, DISEASES OF). (See also COAGULATION.)... warfarin

Cochlear Implant

A device used to treat profoundly deaf people who are not helped by hearing aids. A cochlear implant consists of tiny electrodes surgically implanted in the cochlea deep in the inner ear and a receiver that is embedded in the skull just behind and above the ear. A microphone, sound processor, and transmitter are worn externally. A cochlear implant does not restore normal hearing, but it enables patterns of sound to be detected. Combined with lip-reading, it may enable speech to be understood.... cochlear implant

Deafness

Complete or partial loss of hearing in 1 or both ears. There are 2 types of deafness: conductive deafness, which results from faulty propagation of sound from the outer to the inner ear; and sensorineural deafness, in which there is a failure in transmission of sounds to the brain. Hearing tests can determine whether deafness is conductive or sensorineural.

The most common cause of conductive deafness in adults is earwax. Otosclerosis is a less common cause and is usually treated by an operation called stapedectomy, in which the stapes (a small bone in the middle ear) is replaced with an artificial substitute. In a child, conductive deafness usually results from otitis media or glue ear. This condition may be treated by surgery (see myringotomy). In rare cases, deafness results from a perforated eardrum (see eardrum, perforated). Sensorineural deafness may be present from birth. This type of deafness may result from a birth injury or damage resulting from maternal infection with rubella at an early stage of pregnancy. Inner-ear damage may also occur soon after birth as the result of severe jaundice. Deafness at birth is incurable. Many children who are born deaf can learn to communicate effectively, often by using sign language. Cochlear implants may help those children born profoundly deaf to learn speech.

In later life, sensorineural deafness can be due to damage to the cochlea and/or labyrinth. It may result from prolonged exposure to loud noise, to Ménière’s disease, to certain drugs, or to some viral infections. The cochlea and labyrinth also degenerate naturally with old age, resulting in presbyacusis. Sensorineural deafness due to damage to the acoustic nerve may be the result of an acoustic neuroma. Deafness may be accompanied by tinnitus and vertigo. Sometimes it can lead to depression.

People with sensorineural deafness usually need hearing-aids to increase the volume of sound reaching the inner ear. Lip-reading is invaluable for deaf people. Other aids, such as an amplifier for the earpiece of a telephone, are available. (See also ear; hearing.)... deafness

Macular Degeneration

A progressive, painless disorder affecting the macula. The result is a roughly circular area of blindness that increases in size until it is large enough to obscure 2 or 3 words at reading distance. Macular degeneration does not cause total blindness as vision is retained around the edges of the visual fields. This condition is a common disorder in elderly people.

Of the 2 types of macular degeneration that may occur, one type is usually remedied by laser treatment.

There is no treatment for the other form, although the affected person may benefit from aids such as magnifying instruments.... macular degeneration

Braille

n. an alphabet, developed by Louis Braille (1809–1852) in 1837, in which the letters are represented by patterns of raised dots, which are read by feeling with the finger tips. It is the main method of reading used by the blind.... braille

X-rays

Also known as Röntgen rays, these were discovered in 1895 by Wilhelm Conrad Röntgen. Their use for diagnostic imaging (radiology) and for cancer therapy (see RADIOTHERAPY) is now an integral part of medicine. Many other forms of diagnostic imaging have been developed in recent years, sometimes also loosely called ‘radiology’. Similarly the use of chemotherapeutic agents in cancer has led to the term oncology which may be applied to the treatment of cancer by both drugs and X-rays.

The rays are part of the electro-magnetic spectrum; their wavelengths are between 10?9 and 10? 13 metres; in behaviour and energy they are identical to the gamma rays emitted by radioactive isotopes. Diagnostic X-rays are generated in an evacuated tube containing an anode and cathode. Electrons striking the anode cause emission of X-rays of varying energy; the energy is largely dependent on the potential di?erence (kilovoltage) between anode and cathode. The altered tissue penetration at di?erent kilovoltages is used in radiographing di?erent regions, for example in breast radiography (25–40 kV) or chest radiography (120–150 kV). Most diagnostic examinations use kilovoltages between 60 and 120. The energy of X-rays enables them to pass through body tissues unless they make contact with the constituent atoms. Tissue attenuation varies with atomic structure, so that air-containing organs such as the lung o?er little attenuation, while material such as bone, with abundant calcium, will absorb the majority of incident X-rays. This results in an emerging X-ray pattern which corresponds to the structures in the region examined.

Radiography The recording of the resulting images is achieved in several ways, mostly depending on the use of materials which ?uoresce in response to X-rays. CONTRAST X-RAYS Many body organs are not shown by simple X-ray studies. This led to the development of contrast materials which make particular organs or structures wholly or partly opaque to X-rays. Thus, barium-sulphate preparations are largely used for examining the gastrointestinal tract: for example, barium swallow, barium meal, barium follow-through (or enteroclysis) and barium enema. Water-soluble iodine-containing contrast agents that ionise in solution have been developed for a range of other studies.

More recently a series of improved contrast molecules, chie?y non-ionising, has been developed, with fewer side-effects. They can, for example, safely be introduced into the spinal theca for myeloradiculography – contrast X-rays of the spinal cord. Using these agents, it is possible to show many organs and structures mostly by direct introduction, for example via a catheter (see CATHETERS). In urography, however, contrast medium injected intravenously is excreted by the kidneys which are outlined, together with ureters and bladder. A number of other more specialised contrast agents exist: for example, for cholecystography – radiological assessment of the gall-bladder. The use of contrast and the attendant techniques has greatly widened the range of radiology. IMAGE INTENSIFICATION The relative insensitivity of ?uorescent materials when used for observation of moving organs – for example, the oesophagus – has been overcome by the use of image intensi?cation. A faint ?uorographic image produced by X-rays leads to electron emission from a photo-cathode. By applying a high potential di?erence, the electrons are accelerated across an evacuated tube and are focused on to a small ?uorescent screen, giving a bright image. This is viewed by a TV camera and the image shown on a monitor and sometimes recorded on videotape or cine. TOMOGRAPHY X-ray images are two-dimensional representations of three-dimensional objects. Tomography (Greek tomos

– a slice) began with X-ray imaging produced by the linked movement of the X-ray tube and the cassette pivoting about a selected plane in the body: over- and underlying structures are blurred out, giving a more detailed image of a particular plane.

In 1975 Godfrey Houns?eld introduced COMPUTED TOMOGRAPHY (CT). This involves

(i) movement of an X-ray tube around the patient, with a narrow fan beam of X-rays; (ii) the corresponding use of sensitive detectors on the opposite side of the patient; (iii) computer analysis of the detector readings at each point on the rotation, with calculation of relative tissue attenuation at each point in the cross-sectional plant. This invention has enormously increased the ability to discriminate tissue composition, even without the use of contrast.

The tomographic e?ect – imaging of a particular plane – is achieved in many of the newer forms of imaging: ULTRASOUND, magnetic resonance imaging (see MRI) and some forms of nuclear medicine, in particular positron emission tomography (PET SCANNING). An alternative term for the production of images of a given plane is cross-sectional imaging.

While the production of X-ray and other images has been largely the responsibility of radiographers, the interpretation has been principally carried out by specialist doctors called radiologists. In addition they, and interested clinicians, have developed a number of procedures, such as arteriography (see ANGIOGRAPHY), which involve manipulative access for imaging – for example, selective coronary or renal arteriography.

The use of X-rays, ultrasound or computerised tomography to control the direction and position of needles has made possible guided biopsies (see BIOPSY) – for example, of pancreatic, pulmonary or bony lesions – and therapeutic procedures such as drainage of obstructed kidneys (percutaneous nephrostomy), or of abscesses. From these has grown a whole series of therapeutic procedures such as ANGIOPLASTY, STENT insertion and renal-stone track formation. This ?eld of interventional radiology has close a?nities with MINIMALLY INVASIVE SURGERY (MIS).

Radiotherapy, or treatment by X-rays The two chief sources of the ionising radiations used in radiotherapy are the gamma rays of RADIUM and the penetrating X-rays generated by apparatus working at various voltages. For super?cial lesions, energies of around 40 kilovolts are used; but for deep-seated conditions, such as cancer of the internal organs, much higher voltages are required. X-ray machines are now in use which work at two million volts. Even higher voltages are now available through the development of the linear accelerator, which makes use of the frequency magnetron which is the basis of radar. The linear accelerator receives its name from the fact that it accelerates a beam of electrons down a straight tube, 3 metres in length, and in this process a voltage of eight million is attained. The use of these very high voltages has led to the development of a highly specialised technique which has been devised for the treatment of cancer and like diseases.

Protective measures are routinely taken to ensure that the patient’s normal tissue is not damaged during radiotherapy. The operators too have to take special precautions, including limits on the time they can work with the equipment in any one period of time.

The greatest value of radiotherapy is in the treatment of malignant disease. In many patients it can be used for the treatment of malignant growths which are not accessible to surgery, whilst in others it is used in conjunction with surgery and chemotherapy.... x-rays

Essential Oils

Volatile oils. Out of 250,000 flowering plants only 2,000 yield essential oils. Soluble in alcohol, colourless. Contained in plants, they are responsible for taste, aroma and medicinal action. Organic properties give the flower its scent. May be anti-bacterial, antispasmodic, sedative, expectorant, antiseptic, anti-inflammatory. The smell of a flower roughly conveys the potency of its oil. An example is menthol in the mint family.

Oils used in Phytotherapy: Almond, English Chamomile, Aniseed, Bergamot, Black Pepper, Buchu, Camphor, Cedarwood, Cloves, Coriander, Cypress, Eucalyptus, Geranium, Juniper, Lavender (French), Lavender (English), Lavender (Spanish), Lemon, Marjoram, Orange (sweet), Patchouli, Peppermint, Pine (Scots), Rosemary, Sage, Sandalwood, Thyme, Spearmint, St John’s Wort, Turpentine, Ylang Ylang.

Most oils are obtained by steam distillation. Being highly concentrated, internal use is by a few drops, diluted. About 30-40 are used medicinally; each having its own specific healing properties. Some are convenient as inhalants; a few drops on a tissue for relief of catarrh, colds, etc. Fragrant burners and electronic diffusers are available for vapour-inhalation. Bring to boil 2 pints water; allow to stand 3-4 minutes; sprinkle on the surface 5-10 drops Eucalyptus oil and with towel over head, inhale steam, 5-10 minutes.

Examples: (a) equal parts dilute oils of Thyme and Hypericum (acute middle ear inflammation) 3-4 drops injected into ear 2-3 times daily. (b) 10 drops oil Marjoram in bath water for cramp. Eucalyptus is a useful antibacterial; Cinnamon (anti-inflammatory), Juniper (urinary antiseptic), Orange blossom (anti- depressant), Lavender (sedative).

Essential oils should never be used neat, except as prescribed by a suitably qualified practitioner. While aromatherapists do not prescribe internally, Dr Paul Belaiche, one of France’s leading experts on essential oils, advises oral medication at a maximum daily dosage of 12 drops according to the oil. He advises drops on the tongue, on activated charcoal, in capsule form using a suitable excipient or vegetable oil, or mixed with a little honey. Anal injection has proved successful, (8-10 drops in 10ml vegetable oil) or suppositories made from 200-300mg (8-10 drops) essential oil to 2 grams of base per suppository. Oils should never be allowed to touch the eyes.

Capsules of Garlic oil may be inserted into the rectum for worms or prostate disorder. OR: 10 drops oil mixed with 10ml vegetable oil and injected with the aid of a pipette. Dilute oil of Thyme is used as a massage-rub for chest infections. Oil of Cloves is not only an antiseptic but an analgesic to assuage moderate dental pain. Volatile oils reflexly stimulate the medulla through the olfactory nerve, thus promoting appetite and flow of saliva. All stimulate production of white blood cells and thereby support the immune system.

Oils not used: Basil, Bitter Almonds, Boldo, Calamus, Horseradish, Mugwort, Mustard, Pennyroyal, Rue, Sassafras, Savin, Tansy, Thuja, Wormseed.

Oils not used in pregnancy: Bay, Buchu, Chamomile, Clary Sage, Cinnamon, Clove, Fennel, Hyssop, Juniper, Marjoram, Myrrh, Peppermint, Rose, Rosemary, Sage, Thyme. All other oils – half the normal amount.

Tea: 2-3 drops, selected oil, on teabag makes 3 cups tea.

Inhalant: 10 drops on tissue, or same amount in hot water to inhale steam.

Bath water: add: 10-15 drops.

Compress: 10-15 drops in half a cup (75ml) milk or water. Soak suitable material and apply.

Massage: 6 drops in two teaspoons ‘carrier’ vegetable oil (Almond, Peanut, Olive, etc).

Fragrant oils replace hospital smell.

Essential oil suppliers: Butterbur and Sage, 101 Highgrove Street, Reading RG1 5EJ. Also: Shirley Price Aromatherapy, Wesley House, Stockwell Road, Hinckley, Leics LE10 1RD. ... essential oils

Vision Tests

The part of an eye examination that determines whether there is any reduction in the ability to see. Most vision tests (for example the Snellen chart) are tests of visual acuity.

In this type of test, a device called a phoropter is used to hold different lenses in front of each eye.

The lenses in the phoropter are changed until the letters near the bottom of the Snellen chart can be read.

Tests of visual field may also be performed to assess disorders of the eye and the nervous system.

Refraction tests can detect hypermetropia, myopia, or astigmatism; the effect of lenses on movements of light reflected from the eye is observed to calculate the corrective glasses or contact lenses needed.

If presbyopia is suspected, close-reading tests are used to assess accommodation.... vision tests

Hearing Therapy

the support and rehabilitation of people with hearing difficulties, tinnitus, or vertigo. It includes supplying help with acclimatizing to *hearing aids, teaching lip-reading, advising on *environmental hearing aids, and offering general information and advice regarding the auditory system. Other functions are to explain such conditions as *Ménière’s disease and *otosclerosis and to provide *tinnitus retraining therapy (TRT) and other forms of tinnitus management.... hearing therapy

Labiomancy

n. lip-reading.... labiomancy

Trifocal Lenses

lenses in which there are three segments. The upper provides a clear image of distant objects; the lower is used for reading and close work; and the middle one for the intermediate distance. Musicians sometimes find the middle segment useful for reading the score during performance.... trifocal lenses

Vernier

n. a device for obtaining accurate measurements of length, to 1/10th, 1/100th or smaller fractions of a unit. It consists of a fixed graduated main scale against which a shorter vernier scale slides. The vernier scale is graduated into divisions equal to nine-tenths of the smallest unit marked on the main scale. The vernier scale is often adjusted by means of a screw thread. A reading is taken by observing which of the markings on the scales coincide.... vernier

Standard Deviation

(in statistics) a measure of the dispersion of data about their arithmetic *mean, which is calculated from the square root of the variance of the readings in the series. The arithmetic sum of the amounts by which each observation varies from the mean must be zero, but if these variations are squared before being summated, a positive value is obtained: the mean of this value is the variance. (In practice a more reliable estimate of variance is obtained by dividing the sum of the squared deviations by one less than the total number of observations.) A large standard deviation indicates that data points vary across a wide range of values, whereas a small standard deviation indicates the opposite. See also significance.

standard error of the mean (SEM) the *standard deviation within a sample of observations divided by the square root of the number of observations comprising that sample. The SEM measures the extent to which the means of several different samples taken repeatedly from the same population would vary. It is therefore an indication of the accuracy of the sample mean as an estimate of the mean of the population as a whole.... standard deviation

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