Ophthalmology Health Dictionary

Extrusion of the abdominal VISCERA or internal organs, usually as the result of serious injury. (Usually described as disembowelment when deliberately carried out by one person on another.) In surgery the term refers to part-removal of the viscera, and in OPHTHALMOLOGY it is an operation to remove the contents of the eyeball (see also EYE).... evisceration

Laser stands for Light Ampli?cation by Stimulated Emission of Radiation. The light produced by a laser is of a single wavelength and all the waves are in phase with each other, allowing a very high level of energy to be projected as a parallel beam or focused on to a small spot.

Various gases, liquids and solids will emit light when they are suitably stimulated. A gassed laser is pumped by the ionising e?ect of a high-voltage current. This is the same process as that used in a ?uorescent tube. Each type of laser has a di?erent e?ect on biological tissues and this is related to the wavelength of the light produced. The wavelength determines the degree of energy absorption by di?erent tissues, and because of this, di?erent lasers are needed for di?erent tasks. The argon laser produces light in the visible green wavelength which is selectively absorbed by HAEMOGLOBIN. It heats and coagulates (see COAGULATION) tissues so can be used to seal bleeding blood vessels and to selectively destroy pigmented lesions. The carbon-dioxide laser is the standard laser for cutting tissue: the infra-red beam it produces is strongly absorbed by water and so vaporises cells. Thus, by moving a ?nely focused beam across the tissue, it is possible to make an incision.

The two main uses of laser in surgery are the endoscopic (see ENDOSCOPE) photocoagulation of bleeding vessels, and the incision of tissue. Lasers have important applications in OPHTHALMOLOGY in the treatment of such disorders as detachment of the retina and the diabetic complications of proliferative retinopathy and of the cornea (see EYE, DISORDERS OF). The destruction of abnormal cells – a sign of pre-malignancy – in the CERVIX UTERI is done using lasers. The beams may also be used to remove scar tissue from the FALLOPIAN TUBES resulting from infection, thus unblocking the tubes and improving the chances of CONCEPTION. Lasers also have several important applications in DERMATOLOGY. They are used in the treatment of pigmented lesions such as LENTIGO, in the obliteration of port-wine stains, in the removal of small, benign tumours such as verrucas, and ?nally in the removal of tattoos.

Low-intensity laser beams promote tissue healing and reduce in?ammation, pain and swelling. Their e?ect is achieved by stimulating blood and lymph ?ow and by cutting the production of PROSTAGLANDINS, which provoke in?ammation and pain. The beams are used to treat ligament sprains, muscle tears and in?amed joints and tendons.

The three great advantages of lasers are their potency, their speed of action, and the ability to focus on an extremely small area. For these reasons they are widely used, and have allowed great advances to be made in microsurgery, and particularly in FIBREOPTIC ENDOSCOPY.... laser

The surgical removal of all organs and soft tissue in a body cavity, usually to arrest the growth of a cancer. It is sometimes used in ophthalmology when the eye and the contents of the eye orbit are removed.... exenteration

An e?ective local anaesthetic for topical application. Rapidly absorbed from mucous membranes, it should never be applied to in?amed, traumatised or highly vascular surfaces – nor used when providing anaesthesia for bronchoscopy or cystoscopy. Amethocaine is used in ophthalmology and in skin preparations. It may sensitise the skin. (See ANAESTHESIA.)... amethocaine

Datura metel

Solanaceae

San: Dhustura Hin.: Kaladhatura

Ben: Dhatura Mal: Ummam Kan; Dattura

Tam: Vellummattai

Tel: Tellavummetta

Importance: Downy datura or thorn apple is an erect branched under shrub whose intoxicating and narcotic properties have been made use of by man from ancient time. The plant and fruit are spasmolytic, anticancerous and anthelmintic. Leaves and seeds are inhaled in whooping cough, asthma and other respiratory diseases. Root, leaf and seed are febrifuge, antidiarrhoeal, anticatarrhal and are used in insanity, cerebral complications and skin diseases. Leaf is antitumour, antirheumatic and vermicide. Flower is antiasthamatic, anaesthetic and is employed in swellings and eruptions on face. Fruit juice is used in earache and seed decoction in ophthalmia. For the rheumatic swellings of joints, lumbago, sciatica and neuralgia, warm leaf smeared with an oil is used as a bandage or sometimes the leaf is made into a poultice and applied. The root boiled with milk is used in insanity. It is also an ingredient in the ayurvedic preparation Kanakasva used in bronchial troubles, and the Unani formulations “Roghan dhatura” used as a massage oil for the paralysed part. The alkaloids of pharmaceutical interest present in the plant are hyoscyamine, hyoscine and meteloidine. Datura is the chief commercial source of hyoscine available from natural source. Hyoscine, in the form of hyoscine hydrobromide, is used as a pre-anaesthetic in surgery, child birth, ophthalmology and prevention of motion sickness. It is also employed in the relief of withdrawal symptoms in morphine and alcoholic addiction, paralysis agitans, post- encephaletic parkinsonianism and to allay sexual excitement. Hyoscyamine and its salt hyoscyamine sulphate and hyoscyamine hydrobromide are used in delerium, tremour, menia and parkinsonianism (Kaul and Singh, (1995).

Distribution: Datura is distributed throughout the world, particularly the warmer regions. Datura stramonium is indigenous to India. Out of 15 species reported from different parts of the world, only 10 are known to occur in India. They are found commonly in wastelands, gardens and roadsides. They are distributed in rich localities under semi -arid and arid regions of Punjab, Haryana, Rajastan, and Gujarat; the Central Plateau of Andhra Pradesh and Maharastra and the southern peninsular region of Tamil Nadu. Datura innoxia is indigenous to Mexico and is distributed in Latin American countries. A wealth of genetic stock on genotypes and varieties are maintained in several research institutes in Germany, Bulgaria, USSR and Poland.

Botany: The genus Datura, belonging to the family solanaceae, consists of annual and perennial herbs, shrubs and trees. Three species,viz, Datura metel Linn., D. stramonium Linn. and D. innoxia Mill. are medicinally important. D. innoxia mill. and D. metel Linn. (var. alba, and var, fastuosa) are the choice drug plants, rich in hyoscine. D. metel Linn. is the most common in India. The names, D. metel Linn., D. fastuosa Linn., D. alba Nees., D. fastuosa Linn. var. alba (Nees) C.B. Clarke and D. metel Linn. var. fastuosa (Linn.) Safford are synonymously used by many workers. Two varieties are often noted in D. metel Linn., namely the white flowered var. alba and purple flowered var. fastuosa. D. metel Linn. is an erect succulent branched undershrub divaricate often purplish branches and ovate pubescent leaves which are oblique at the base of lamina. Flowers are large, solitary, short pedicelled, purplish outside and white inside. Fruits are sub-globose capsules covered all over with numerous, fleshy prickles, irregularly breaking when mature. Seeds are numerous, smooth, yellowish brown. (warrier et al, 1994).

Agrotechnology: Datura grows well in a wide range of climate from tropical to temperate conditions.

The plant thrives best in areas of low rainfall where winter and monsoon rains are followed by long dry periods. Areas with annual rainfall below 1000mm with mean temperature of 10-15oC in winter and 27 - 28oC in May-June are ideal. The crop cannot stand frost, high rainfall or high temperature in the plains in May-June. It grows on majority of soils, however, alkaline or neutral clay loam soil or those tending to saline-alkaline reaction rich in organic matter are ideal for vigorous growth. The clayey, acidic, water-logged or moisture deficient soils do not suit this crop.

The plant is propagated by seeds but it is characterised by poor and often erratic seed germination which can be improved either by leaching out the inhibitor from the seeds or by alternate freezing and thawing of seeds. The optimum season for raising the crop is Rabi in tropical and subtropical areas while Kharif in temperate areas. The seeds can be broadcast - sown or seedlings can be raised in nursery and then transplanted. Seed rate is 7-8 kg/ha for broadcasting and 2-3 kg/ha. for transplanting. The field is ploughed and disced adequately to produce fine seed bed. In the case of direct seeding, seeds are drilled in rows taken 45-60 cm apart. The plants are thinned to keep a spacing of 30-45 cm at the time of first weeding. In the case of transplanting 4-6 weeks old seedlings are planted at 45-60 x 30-45 cm spacing. The field should be irrigated immediately after sowing or planting if soil moisture is inadequate. Thereafter 3-4 irrigations may be given if sufficient rainfall is not received. Application of organic manure at 10-15 t/ha and fertilisers at 60:40:40 kg N, P2O5 and K2O/ha is recommended for the crop for better growth and yield N may be applied in 3-4 equal split doses at planting and after each weeding which is required 2-3 times during the growing season. Application of micronutrients is reported to improve the alkaloid contents. No major insect pest is known to attack this crop. However, leaf spot, wilt and mosaic diseases cause damage to this crop. Leaf spot is caused by Alternaria tennuissima (Nees) Wiltshire and characterised by brown round to oval spots, becoming necrotic at later stage which leads to withering and dropping of leaves. Wilt is caused by Sclerotium rolfsii Sace; it starts with dropping of leaves and finally wilting of the entire plant. Root and foot wilt, caused by Corticium solani, appears as damping off of seedlings and mature plants. Datura distortion mosaic is characterised by yellowing of the veins followed by inward rolling and distortion of leaves with a reduction in plant size. For reducing the impact of these diseases, field sanitation, use of resistant varieties, crop rotation for 3-4 years and fungicide application should be resorted to. For the purpose of leaf and top, harvesting is done as soon as flowering starts. Entire top containing leaves and twigs is cut, dried in shade and stored in gunny bags. For seed and fruit, fully grown fruits, still green are picked 2-3 times before final harvest when the entire plant is cut from the base and dried in the open. The dried fruits are then thrashed with a stick to separate the seeds. The seed yield is 1-1.5 t/ha. (Husain, 1993; Kaul and Singh, 1995)

Properties and activity: The alkaloids hyoscyamine and hyoscine (scopolamine) and meteloidine are found in all parts of the plant. The total alkaloid content is 0.26 - 0.42 % Fruits contain daturaolone and daturadiol while roots contain additionally ditigloyloxy tropane derivatives, tigloidine, apohyoscine, norhyoscine, norhyocyamine, cusiohygrine and tropine. Other alkaloids isolated from the plant are apohyoscyamine, DL-scopolamine, normeteloidine, tigloylputrescine, scopine, nortigloidine, tropine, psuedo valeroidine, fastudine, fastunine, fastusinine, 7-hydroxy-3, 6-ditigloyloxytropane (2) datura nolone and fastusic acid. The physiological effects of hyoscyamine are qualitatively the same as those of its recemic derivative atropine. This is relatively more active in its paralysing affect on nerve endings and less active in its stimulant action on the central nervous system. The sedative and hypnotic action of hyoscyamine is weaker than that of hyoscine. Atropine has a stimulant action on the central nervous system and depresses the nerve endings to the secretary glands and plain muscles. The plant or the different alkaloids have narcotic, anthelmintic, spasmolytic anaesthetic, sedative, ophthalmic, anticancerous, antitumour, antirheumatic, antiasthmatic, antidiarrhoeal and anticatarrhal activities. (Thakur et al, 1989).... datura

Mill.

Synonym: D. metel auct. non Linn.

Family: Solanaceae.

Habitat: Western Himalayas and hilly regions of the western parts of Peninsular India, abundantly in Maharashtra.

English: Thornapple.

Ayurvedic: Dhattuura.

Unani: Dhaturaa, Joz Maasil.

Action: The plant is the source of alkaloid scopolamine which is used as a pre-anaesthetic in surgery and childbirth, in ophthalmology and for the prevention of motion sickness.

Hyoscyamine and hyoscine and me- teloidine were found in the leaves, flowers, pericarp and seeds of the plant. The root gave tropane, tropine and pseu- dotropine.... datura innoxia

An institution providing treatment for sick and injured persons. This may be done on an inpatient or outpatient basis. A hospital provides investigative and therapeutic services which are not available on a domiciliary basis.

Hospitals are broadly divided into general hospitals (available in each district in the United Kingdom) and hospitals specialising in particular ailments (e.g. ophthalmology; ear, nose and throat; neurology, etc.). In addition there are teaching hospitals which have the dual function of patient care and the education of medical sta?. (See NATIONAL HEALTH SERVICE (NHS).)

In the UK all patients are entitled to hospital care provided by their NHS trust when referred by their GENERAL PRACTITIONER (GP) or admitted via the Accident & Emergency department. (In exceptional cases, patients with severe mental illness can be compulsorily admitted by the authorities.) Admission will depend on clinical priority, as demand commonly exceeds supply of beds in some localities. Private hospital care is available under the care of a consultant of choice, provided that the patient is covered by appropriate private medical insurance or can pay direct the substantial hospital and medical fees.

The future development of hospital medicine is controversial, but the long-term future may well see many fewer, much better equipped, highly specialised hospitals for patients requiring high-technology-based treatments. These might be backed up with a range of smaller general (or halfway) hospitals caring for patients with less demanding clinical needs who nevertheless require some bed-based care. Many more patients requiring routine specialist treatment will be treated as day patients than is the case now, and there will (or should) be much greater emphasis (with appropriate resources) on PREVENTIVE MEDICINE.

Britain is experimenting with a prototype ‘virtual hospital’. The project will target hospital patients who need to remain under the care of specialists but whose condition can be managed at home. Suitable NHS patients will be provided with monitoring equipment that enables them, for example, to read their own blood pressure, lung and heart functions, with the results transferred electronically to the o?ce of relevant specialists who will prescribe and monitor treatment.... hospital

A doctor with specialist training in OPHTHALMOLOGY.... ophthalmologist

That branch of medicine involved in the treatment of injuries, deformities or individual diseases by operation or manipulation. It incorporates: general surgery; specialised techniques such as CRYOSURGERY, MICROSURGERY, MINIMALLY INVASIVE SURGERY (MIS), or minimal access (keyhole) surgery, and stereotactic sugery (see STEREOTAXIS); and surgery associated with the main specialties, especially cardiothoracic surgery, gastroenterology, GYNAECOLOGY, NEUROLOGY, OBSTETRICS, ONCOLOGY, OPHTHALMOLOGY, ORTHOPAEDICS, TRANSPLANTATION surgery, RECONSTRUCTIVE (PLASTIC) SURGERY, and UROLOGY. Remotely controlled surgery using televisual and robotic techniques is also being developed.

It takes up to 15 years to train a surgeon from the time at which he or she enters medical school; after graduating as a doctor a surgeon has to pass a comprehensive two-stage examination to become a fellow of one of the ?ve recognised colleges of surgeons in the UK and Ireland.

Surgery is carried out in specially designed operating theatres. Whereas it used to necessitate days and sometimes weeks of inpatient hospital care, many patients are now treated as day patients, often under local anaesthesia, being admitted in the morning and discharged later in the day.

More complex surgery, such as transplantation and neurosurgery, usually necessitates patients being nursed post-operatively in high-dependency units (see INTENSIVE THERAPY UNIT (ITU)) before being transferred to ordinary recovery wards. Successful surgery requires close co-operation between surgeons, physicians and radiologists as well as anaesthetists (see ANAESTHESIA), whose sophisticated techniques enable surgeons to undertake long and complex operations that were unthinkable 30 or more years ago. Surgical treatment of cancers is usually done in collaboration with oncologists. Successful surgery is also dependent on the skills of supporting sta? comprising nurses and operating-theatre technicians and the availability of up-to-date facilities.... surgery

Recurring headache commencing with constriction of blood vessels of the brain, followed by expansion which allows engorgement of vessels. Single or double-sided. With nausea, vomiting, speech difficulties, visual disturbances, emotional stress, tension.

“Half of all migraine patients suffer from anxiety, and one in five experiences depression,” according to a study carried out at Manchester University. (Dr Jennifer Devlen)

Causes: many and varied. Alcohol, excess coffee and caffeine stimulants, gluten food allergies, dairy products, chocolate, citrus fruits. Related to carbohydrate metabolism. May be associated with menstruation or emotional disturbance, nervous or physical fatigue; liver, stomach or kidney disturbance, or The Pill.

Symptoms: temporary blindness, or sight may be only half the visual field. Flashing lights, throbbing headache, loud noises worsen, nausea, vomiting, depression.

Treatment. In the initial (constrictive) stage any of the following simple teas may resolve: German Chamomile, Betony, Skullcap, Wild Thyme, Valerian.

Where the condition has progressed to vasodilation (engorgement of cerebral blood vessels) give any of the following alternatives. Whilst the requirements of each individual case is observed, inclusion of a remedy for stomach and liver may enhance efficacy. Sometimes a timely diuretic to reduce volume of the blood aborts an attack.

Associated with menstrual disorders: Agnus Castus, Evening Primrose oil.

Tea: Formula. (1) Equal parts: Betony, Valerian, Dandelion root. (2) Alfalfa 1; Valerian half; Hops quarter. One heaped teaspoon to each cup boiling water; infuse 15 minutes. Half-1 cup 2-3 times daily. Formula. Skullcap 2; Mistletoe 1; Hops half. Dose: Liquid Extracts: 1-2 teaspoons. Tinctures: 1-3 teaspoons. Powders: 750mg (three 00 capsules or half a teaspoon) 2-3 times daily.

Valerian. German traditional.

Feverfew. 2-3 fresh leaves on bread. Tincture (or essence) 5-10 drops.

Practitioner: Tincture Gelsemium, BPC (1963) 5 drops.

Diet: Fruit juice fast. Oily fish. Hay diet. Salt-free.

Vitamins. A. B-complex, B6, B12, C (up to 1000mg). E, Niacin.

Minerals. Manganese, Calcium, Magnesium, Zinc.

Rose-tinted glasses. Ophthalmology Department, Birmingham University.

Information. British Migraine Association, 178A High Road, West Byfleet, Surrey KT14 7ED. Send SAE. ... migraine

A harmless orange dye used in ophthalmology as an aid to the diagnosis of certain eye disorders.... fluorescein

Use of a laser beam in a variety of medical procedures. Highintensity laser beams cut through tissue and cause blood clotting. They can be used in surgery and to destroy abnormal blood vessels. Lasers are frequently used in ophthalmology to treat eye disorders, in gynaecology (for example, to unblock fallopian tubes), and to remove birthmarks and tattoos.... laser treatment

A person who fits and sells glasses or contact lenses. An ophthalmic optician, or optometrist, also examines the eyes to test for myopia, presbyopia, hypermetropia, or astigmatism. People with suspected eye disorders are referred to a specialist called an ophthalmologist.

(See also ophthalmology; optometry.)... optician

The practice of assessing vision to establish whether glasses or contact lenses are needed to correct a visual defect, as carried out by an optometrist. Disorders of the eye may require treatment by an ophthalmologist. (See also ophthalmology; optician.)... optometry

a thermoplastic or thermosetting polymeric material derived from acrylic acid, methacrylic acid, or other related compounds. Acrylic resins are used in dentistry for making denture teeth, denture bases, and orthodontic appliances owing to their good biocompatibility. They are also used in orthopaedic surgery, cosmetic surgery, and ophthalmology for the same reason.... acrylic resin

n. imaging of blood vessels (see also coronary angiography; lymphangiography). In the older form of angiography X-ray imaging was carried out after injection of *radiopaque contrast medium and *digital subtraction applied to enhance visualization. The use of X-rays has now been largely replaced by methods using MRI or CT scanners. Magnetic resonance angiography (MRA) can be performed with (contrast-enhanced) or without (noncontrast) injection of a magnetic resonance contrast agent (see contrast medium). Contrast-enhanced MRA will show the vessels better. These images can be reconstructed in two or three dimensions. Computerized tomographic angiography (CTA) uses a radiographic contrast agent, usually injected into a vein, to increase the visibility of the blood vessels. Fluorescein angiography is a common method of investigation in ophthalmology. *Fluorescein sodium is injected into a vein in the arm, from which it circulates throughout the body. Light of an appropriate wavelength is shone into the eye, causing the dye in the retinal blood vessels to fluoresce. This allows the circulation through the retinal blood vessels to be observed and photographed. Indocyanine green (ICG) angiography uses indocyanine green dye, which fluoresces in infrared light. It is valuable in assessing circulation in the deeper layers of the *fundus.... angiography

(in ophthalmology) areas of hypertrophy of retinal pigment epithelium (see retina) that clinically resemble the prints of bears’ paws.... bear tracks

n. 1. (in neurology) the formation of nerve tracts by fibres coming together into one pathway from different regions of the brain. 2. (in ophthalmology) the ability of the eyes to turn inwards and focus on a near point so that a single image is formed on both retinas. The closer the object, the greater the degree of convergence.... convergence

n. 1. (in ophthalmology) any abnormal position of one or both eyes. For example, if the eyes are both looking to one side when the head is facing forwards, they are said to be deviated to that side. Such deviations of both eyes may occur in brain disease. Deviations of one eye, such as *dissociated vertical deviation, come into the category of squint (see strabismus). 2. see sexual deviation.... deviation

n. 1. (in ophthalmology) simultaneous abduction of the eyes. Divergence excess is a divergent squint (see strabismus) in which the eyes are deviated outwards more when looking in the distance than when looking at near objects. Divergence insufficiency is a convergent squint (see strabismus) in which the eyes are deviated slightly inwards only when looking in the distance. 2. (in ethics) a difference of opinion.... divergence

n. the complete removal of an organ, tumour, or cyst leaving surrounding structures intact. In ophthalmology it is an operation in which the eyeball is removed but the other structures in the socket (e.g. eye muscles) are left in place. Commonly a plastic ball is buried in the socket to give a better cosmetic result when fitting an artificial eye.... enucleation

1. n. the point at which rays of light converge after passing through a lens. 2. n. the principal site of an infection or other disease. 3. n. (in radiography) the point of origin of an X-ray beam. 4. vb. (in ophthalmology) to accommodate (see also accommodation).... focus

n. 1. (in anatomy) a small secretory cavity, sac, or gland, such as any of the cavities in the *ovary in which the ova are formed. See also Graafian follicle; hair follicle. 2. (in ophthalmology) any of the smooth translucent elevations of the conjunctiva produced by an immune response. They are usually associated with viral inflammation. —follicular adj.... follicle

adj. (in ophthalmology) within the *stroma of the cornea.... intrastromal

(OCT) a class of optical tomographic techniques that allows extremely high-quality micrometre-resolution three-dimensional images to be obtained from within optical scattering media (e.g. biological tissue). OCT is proving valuable in ophthalmology, for noninvasive imaging of the ocular structures, and in cardiology for visualizing the interior of coronary arteries using a specialized *catheter. See also spectral domain optical coherence tomography.... optical coherence tomography

n. tapping: the process of drawing off fluid from a part of the body through a hollow needle or *cannula. In ophthalmology, it involves an incision into the anterior chamber of the eye.... paracentesis

adj. (in ophthalmology) denoting the area around the eyeball.... peribulbar

combining form denoting (in ophthalmology) an abnormal deviation of the eyes or turning of the visual axis. Example: heterophoria (tendency to squint).... phoria

adj. (in ophthalmology) describing an optical device consisting of an opaque disc punctured with a fine slit or hole (or holes), which is placed in front of the eye in the same position as glasses and enables sharper vision in cases of gross long- or short-sightedness or astigmatism. It sharpens the image formed on the retina because it confines the light reaching the eye to one or more fine beams, which pass through the centre of the lens undeviated by refractive error. The same principle is used in the pin-hole camera.... stenopaeic

(in Britain) a building, usually owned or leased by a health authority, that houses personnel and/or services from one or more sections of the *National Health Service (e.g. *general practitioners, *district nurses, dentists, and *child health clinics. Services provided by local authorities, such as social services, may also operate from such a centre. A GP-led health centre (polyclinic) is one where a greater range of health services are available compared to conventional GP practices. They offer extended opening hours and other health services, such as ophthalmology and dentistry, as well as diagnostics, outpatient appointments, urgent care, and community services, such as community mental health care, community nursing, and management of long-term conditions. The main aim is to move more services into the community, thus making them easier to access for patients. Various models have been proposed for polyclinics, ranging from large premises housing many separate GP practices to more extensive facilities with additional services available. See also children’s centre.... health centre

n. 1. contraction of a blood clot. When first formed, a blood clot is a loose meshwork of fibres containing various blood cells. Over a period of time this contracts, producing a firm mass that seals the damaged blood vessels. 2. (in ophthalmology) degenerative shrinkage of the vitreous humour due to ageing, which usually results in a *vitreous detachment.... syneresis