Retinal dialysis Health Dictionary

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Retinal Dialysis: From 1 Different Sources

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.
Health Source: Oxford | Concise Colour Medical Dictionary
Author: Jonathan Law, Elizabeth Martin

Dialysis

A procedure used to ?lter o? waste products from the blood and remove surplus ?uid from the body in someone who has kidney failure (see KIDNEYS, DISEASES OF). The scienti?c process involves separating crystalloid and COLLOID substances from a solution by interposing a semi-permeable membrane between the solution and pure water. The crystalloid substances pass through the membrane into the water until a state of equilibrium, so far as the crystalloid substances are concerned, is established between the two sides of the membrane. The colloid substances do not pass through the membrane.

Dialysis is available as either haemodialysis or peritoneal dialysis.

Haemodialysis Blood is removed from the circulation either through an arti?cial arteriovenous ?stula (junction) or a temporary or permanent internal catheter in the jugular vein (see CATHETERS). It then passes through an arti?cial kidney (‘dialyser’) to remove toxins (e.g. potassium and urea) by di?usion and excess salt and water by ultra?ltration from the blood into dialysis ?uid prepared in a ‘proportionator’ (often referred to as a ‘kidney machine’). Dialysers vary in design and performance but all work on the principle of a semi-permeable membrane separating blood from dialysis ?uid. Haemodialysis is undertaken two to three times a week for 4–6 hours a session.

Peritoneal dialysis uses the peritoneal lining (see PERITONEUM) as a semi-permeable membrane. Approximately 2 litres of sterile ?uid is run into the peritoneum through the permanent indwelling catheter; the ?uid is left for 3–4 hours; and the cycle is repeated 3–4 times per day. Most patients undertake continuous ambulatory peritoneal dialysis (CAPD), although a few use a machine overnight (continuous cycling peritoneal dialysis, CCPD) which allows greater clearance of toxins.

Disadvantages of haemodialysis include cardiovascular instability, HYPERTENSION, bone disease, ANAEMIA and development of periarticular AMYLOIDOSIS. Disadvantages of peritoneal dialysis include peritonitis, poor drainage of ?uid, and gradual loss of overall e?ciency as endogenous renal function declines. Haemodialysis is usually done in outpatient dialysis clinics by skilled nurses, but some patients can carry out the procedure at home. Both haemodialysis and peritoneal dialysis carry a relatively high morbidity and the ideal treatment for patients with end-stage renal failure is successful renal TRANSPLANTATION.... dialysis

Peritoneal Dialysis

See dialysis.... peritoneal dialysis

Retinal Artery Occlusion

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

Retinal Detachment

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

Retinal Vein Occlusion

Blockage of a vein carrying blood away from the retina.

It usually results from thrombosis in the affected vein, and is more common in people who have glaucoma.

Retinal vein occlusion may cause visual disturbances, glaucoma, or blindness.... retinal vein occlusion

Eyes  - Retinal Haemorrhage

See: BLEEDING. ... eyes  - retinal haemorrhage

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

Retinal Tear

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

Acute Retinal Necrosis

(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

Retinal

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

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