Retinal vein occlusion Health Dictionary

The way that the TEETH ?t together when the jaws close. Also the closing or obstruction of a duct, hollow organ, or blood vessel.... occlusion

The prominent vein which runs from near the bend of the elbow upwards along the inner side of the upper arm.... basilic vein

The vein which carries to the LIVER, blood that has been circulating in many of the abdominal organs. It is peculiar among the veins of the body in that it ends by breaking up into a capillary network instead of carrying the blood directly to the heart – a peculiarity which it shares only with certain small vessels in the kidneys. The PORTAL SYSTEM begins below in the haemorrhoidal plexus of veins around the lower end of the rectum; from this point, along the whole length of the intestines, the blood is collected into an inferior mesenteric vein upon the left, and a superior mesenteric vein upon the right side. The inferior mesenteric vein empties into the splenic vein, and the latter, uniting with the superior mesenteric vein immediately above the pancreas, forms the portal vein. The portal vein is joined by veins from the stomach and gallbladder, and ?nally divides into two branches which sink into the right and left lobes of the liver. (For their further course, see LIVER).

The organs from which the portal vein collects the blood are the large and small intestines, the stomach, spleen, pancreas, and gall-bladder.... portal vein

See thrombosis, deep vein.... deep vein thrombosis

One of 3 veins on each side of the neck that return deoxygenated blood from the head to the heart. The internal jugular, the largest of the 3 (internal, external, and anterior), arises at the base of the skull, travels down the neck alongside the carotid arteries, and passes behind the clavicle, where it joins the subclavian vein (the large vein that drains blood from the arms).... jugular vein

Blockage of an artery supplying blood to the retina, most commonly due to thrombosis or embolism, The disorder can result in permanent blindness or loss of part of the field of vision, depending on the artery affected and whether or not the condition can be treated quickly enough.... retinal artery occlusion

Separation of the retina from the outer layers at the back of the eye. Detachment may follow an eye injury but usually occurs spontaneously. It is usually preceded by a retinal tear, and is more common in highly myopic (shortsighted) people and in people who have had cataract surgery.

The detachment is painless. The first symptom is either bright flashes of light at the edge of the field of vision, accompanied by floaters, or a black “drape” obscuring vision.

Urgent treatment is required and usually involves surgical repair of the underlying tear. If the macula (site of central vision) has not been detached, the results can be excellent.... retinal detachment

A major vein that runs the length of the leg just under the skin.

It is sometimes removed and used to bypass a blockage in blood vessels of the heart (see coronary artery bypass).... saphenous vein

A vessel that returns blood towards the heart from the various organs and tissues of the body. The walls of veins, like those of arteries, consist of a smooth inner lining, a muscular middle layer, and a fibrous outer covering. However, blood pressure in veins is lower than in arteries, and the walls of veins are thinner, less elastic, less muscular, and weaker than those of arteries. The linings of many veins contain folds, which act as valves, ensuring that blood flows only towards the heart. Blood is helped on its way through the veins by pressure on the vessel walls from the contraction of surrounding muscles. (See also circulatory system.) A... vein

When coronary arteries, narrowed by disease, cannot supply the heart muscle with su?cient blood, the cardiac circulation may be improved by grafting a section of vein from the leg to bypass the obstruction. Around 10,000 people in the United Kingdom have this operation annually and the results are usually good. It is a major procedure that lasts several hours and requires the heart to be stopped temporarily, with blood circulation and oxygenation taken over by a HEART-LUNG MACHINE.... coronary artery vein bypass grafting (cavbg)

See THROMBOSIS; VEINS, DISEASES OF.... deep vein thrombosis (dvt)

See: BLEEDING. ... eyes  - retinal haemorrhage

Bleeding into the retina from 1 or more blood vessels, due to diabetes mellitus, hypertension, or retinal vein occlusion. When the macula

(site of central vision) is involved, vision is severely impaired.

Peripheral haemorrhages may be detected only when the eye is examined with an ophthalmoscope.... retinal haemorrhage

The development of a split in the retina, usually caused by degeneration.

A tear is more common in people with severe myopia.

A retinal tear may also be caused by a severe eye injury.

Retinal detachment usually follows a retinal tear.

If a retinal tear is found before there is any detachment, the hole is sealed by laser treatment or cryopexy (application of extreme cold).... retinal tear

(ARN) severe inflammation and necrosis of the retina associated with inflammation and blockage of retinal blood vessels, haemorrhage and death of retinal tissue, and retinal detachment. It may affect both eyes (bilateral acute retinal necrosis, BARN), and visual prognosis is poor. ARN is thought to be due to viral infection.... acute retinal necrosis

The formation of a thrombus within deep-lying veins in the leg. The cause is usually a combination of slow blood flow through 1 part of the body (such as when sitting for long periods or when the tissues are compressed, as occurs in long-haul aircraft flights) and an increase in the clotting tendency of the blood, which occurs with dehydration, after surgery or injury, during pregnancy, and in women taking oral contraceptives. Deep vein thrombosis may also be caused by polycythaemia. Deep vein thrombosis is common in people with heart failure and those who have had a stroke or who have been immobile for long periods. Clots in the leg veins may cause pain, tenderness, swelling, discoloration, and ulceration of the skin, but they can be symptomless. A deep vein thrombosis is not necessarily serious in itself, but part of the clot may break off and travel in the bloodstream to the lungs. This is known as a pulmonary embolism.

A diagnosis is made by doppler ultrasound scanning.

Treatment depends on the site and extent of the clots.

Small clots may not need treatment if they are confined to the calf and the patient is mobile.

Otherwise, anticoagulant drugs or thrombolytic drugs are given.

If there is a high risk of a pulmonary embolism, thrombectomy may be performed.... thrombosis, deep vein

an unpaired vein that arises from the inferior vena cava and drains into the superior vena cava, returning blood from the thorax and abdominal cavities.

b... azygos vein

(CTO) a complete arterial blockage (usually coronary) that has been present for at least three months. Fibrosis and calcification at the site of occlusion are well established by this time, making *percutaneous coronary intervention to open the artery much more difficult.... chronic total occlusion

the combination of major acne, *pilonidal sinus, chronic scalp *folliculitis, and *hidradenitis suppurativa.... follicular occlusion tetrad

one of several short veins originating within the lobes of the liver as small branches, which unite to form the hepatic veins. These lead directly to the inferior vena cava, draining blood from the liver.... hepatic vein

(brachiocephalic vein) either of two veins, one on each side of the neck, formed by the junction of the external jugular and subclavian veins. The two veins join to form the superior vena cava.... innominate vein

a vein carrying oxygenated blood from the lung to the left atrium. See pulmonary circulation.... pulmonary vein

1. (retinene) n. the aldehyde of retinol (*vitamin A). See also rhodopsin. 2. adj. see retina.... retinal

separation of the retina from its insertion at the ora serrata (the anterior margin of the retina, lying just posterior to the ciliary body). This acts as a retinal tear and causes a *retinal detachment.... retinal dialysis

blocking of the Fallopian tubes. This is achieved by surgery as a means of *sterilization; it is also a result of *pelvic inflammatory disease.... tubal occlusion