| focal interval | The distance between the anterior and posterior focal points of the eye. (05 Mar 2000) |
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| focal length | <microscopy> The distance from the optical centre of the lens to the focal point<microscopy> The focal length of an objective and its working distance are directly proportional. (05 Aug 1998) |
| focal lymphocytic thyroiditis | Focal infiltration of the thyroid by lymphocytes and plasma cells. See: Hashimoto's thyroiditis. (05 Mar 2000) |
| focal metastatic disease | Presence of a single area of metastasis of a malignant tumour or infection distant from the primary lesion. (05 Mar 2000) |
| focal motor seizure | A simple partial seizure with localised motor activity. (05 Mar 2000) |
| focal necrosis | Occurrence of numerous, relatively small or tiny, fairly well-circumscribed, usually spheroidal portions of tissue that manifest coagulative, caseous, or gummatous necrosis and are characteristically associated with agents that are haematogenously disseminated; frequently observed only in histologic sections, but the foci may be as large as 1 to 3 mm and macroscopically visible; arbitrarily, foci larger than that are usually not termed focal necrosis. (05 Mar 2000) |
| focal nephritis | Glomerulonephritis affecting a small proportion of renal glomeruli which commonly presents with haematuria and may be associated with acute upper respiratory infection in young males, not usually due to streptococci; associated with IgA deposits in the glomerular mesangium and may also be associated with systemic disease, as in Henoch-Schonlein purpura. Synonym: Berger's disease, Berger's focal glomerulonephritis, focal nephritis, IgA nephropathy. (05 Mar 2000) |
| focal nodular hyperplasia | <radiology> Focal nodules of normal hepatocytes, Kuppfer cells and bile ducts, F more than M, rare, benign, multiple in 20%, haemorrhage (most common complication) in only 2-3% (unlike hepatic adenoma), stellate fibrous septae (stellate scar), NM: normal or increased uptake on HIDA and sulfur colloid (12 Dec 1998) |
| focal point | Location of an organism, for fish, usually the position of the snout. Habitat measurements made at that position (depth, water velocity, etc.) are focal point measurements. (09 Oct 1997) |
| focal reaction | A reaction which occurs at the point of entrance of an infecting organism or of an injection, as in the Arthus phenomenon. Synonym: local reaction. (05 Mar 2000) |
| focal sclerosing glomerulopathy | Focal, segmental glomerulosclerosis reported in adults and children with normal serum complement, progressing to chronic glomerulonephritis. (05 Mar 2000) |
| focal segmental glomerulosclerosis | <nephrology> A kidney disorder that results in fibrosis and scarring in the kidney glomerulus. The cause is unknown but some cases can result from reflux nephropathy. The clinical manifestation of this kidney disorder is nephrotic syndrome. Symptoms include weight gain, swelling, hypertension and foamy urine. High blood cholesterol and triglyceride levels are also seen with this disorder. Treatment has included the use of corticosteroids and immunosuppressives. Antihypertensive agents and diuretics may also be necessary. Over one-half will develop chronic renal failure within 10 years of diagnosis. (27 Sep 1997) |
| focal seizure | <neurology> A brief temporary alteration in movement, sensation or autonomic nerve function caused by abnormal electrical activity in a localised area of the brain. Focal seizures (i.e. Partial or Jacksonian seizures) usually cause no change in awareness or alertness. An example of a focal (partial) seizure would be rhythmic muscle contractions in one area of the body: lip smacking, mouth movements, drooling, head turning, eye movements or seemingly purposeful movements (for example picking at clothes). Other presentations may be strictly sensory with abnormal numbness, tingling or a crawling sensation to the skin. More unusual symptoms include changes in speech, thought, personality, mood, sensation of deja vu or hallucinations. (05 Jan 1998) |
| focal spot | The site of bombardment by electrons and emission of X-rays from the anode of an X-ray tube. See: focal spot size. (05 Mar 2000) |
| focal spot size | The measured size of a focal spot, a function of its actual size and the angulation of the anode surface. See: focal spot. (05 Mar 2000) |