| focal depth | Depth of focus, the greatest distance through which an object point can be moved while maintaining a clear image. Synonym: penetration. (05 Mar 2000) |
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| focal dermal hypoplasia | A genetic skin disease characterised by hypoplasia of the dermis, herniations of fat, and hand anomalies. It is found exclusively in females and transmitted as an x-linked dominant trait. (12 Dec 1998) |
| focal distance | The distance from the centre of a lens to its focus. (05 Mar 2000) |
| focal embolic glomerulonephritis | Glomerulonephritis associated with subacute bacterial endocarditis, frequently producing microscopic haematuria without azotemia. (05 Mar 2000) |
| focal epilepsy | Epilepsy of various aetiologies characterised by focal seizures or secondarily generalised tonic-clonic seizures. Ictal symptoms are often related to the brain region where the seizure begins focally. Synonym: cortical epilepsy, local epilepsy, partial epilepsy. (05 Mar 2000) |
| focal epithelial hyperplasia | Hyperplasia of the mucous membrane of the lips, tongue, and less commonly, the buccal mucosa, floor of the mouth, and palate, presenting soft, painless, round to oval sessile papules about 1 to 4 mm in diameter. The condition usually occurs in children and young adults and has familial predilection, lasting for several months, sometimes years, before running its course. A viral aetiology is suspected, the isolated organism being usually the human papilloma virus. (12 Dec 1998) |
| focal gallbladder wall thickening | <radiology> Primary gall bladder carcinoma, adenomyomatosis / hyperplastic cholecystosis, adenomatous polyps, papillary adenomas, metastatic nodules, cholesterol polyps (associated with acoustic shadowing), metachromatic leukodystrophy (rare!) See also: diffuse thickening (12 Dec 1998) |
| focal gigantism | <radiology> Neurofibromatosis, AVM, Klippel-Trenaunay-Weber syndrome, Beckwith-Wiedemann syndrome, Parks-Davis syndrome, haemangioma, JRA (12 Dec 1998) |
| focal glomerulonephritis | 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 illumination | Illumination in which a beam of light is directed diagonally to an object so that it is brilliantly illuminated while the surrounding area is in shadow. Synonym: lateral illumination, oblique illumination. Kohler illumination, a method of illumination of microscopic objects in which the image of the light source is focused on the substage condenser diaphragm and the diaphragm of the light source is focused in the same plane with the object to be observed; maximises both the brightness and uniformity of the illuminated field. (05 Mar 2000) |
| focal infection | An old term which distinguishes local infection's (focal) from generalised infection's (sepsis). (05 Mar 2000) |
| focal infection, dental | Secondary or systemic infections due to dissemination throughout the body of microorganisms whose primary focus of infection lies in the periodontal tissues. (12 Dec 1998) |
| focal interval | The distance between the anterior and posterior focal points of the eye. (05 Mar 2000) |
| 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) |