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actual focal spot the section of a focal spot on which there is intersection of an electron beam with an anode of an x-ray tube.
Bitot's s's foamy gray triangular spots of keratinized epithelium on the conjunctivae, a sign of vitamin A deficiency.
cherry-red spot the choroid appearing as a red circular area surrounded by gray-white retina, as viewed throught the fovea centralis in tay-sachs disease. Called also Tay's spot.
cotton-wool spot white or gray soft-edged opacities in the retina composed of cytoid bodies; seen in hypertensive retinopathy, lupus erythematosus, and numerous other conditions.
effective focal spot the size of a projected focal spot in a specified direction measured with a quality assurance test tool such as the slit camera.
1. the object of a patient's gaze during distraction techniques.
2. a small area of an x-ray target that receives the main electron stream.
Forschheimer s's a fleeting skin eruption consisting of discrete rose spots on the soft palate sometimes seen in rubella just prior to the onset of the skin rash.
Koplik's s's small, irregular, bright red spots on the buccal and lingual mucosa, with a minute bluish white speck in the center of each; they are pathognomonic of beginning measles.
mental blind spot mental scotoma.
mongolian spot a type of congenital brown to gray-blue nevus; see also mongolian spot.
Roth's s's round or oval white spots consisting of coagulated fibrin seen in the retina in a number of diseases in which a vascular insult resulting in hemorrhage is followed by healing.
Tay's spot cherry-red spot.
A tiny infarct in the retina, present in hypertension, diabetes mellitus, bacterial endocarditis, and other diseases.
See also: spot
A liquid or semisolid which has been discharged through the tissues to the surface or into a cavity. Exudates in the retina are opacities that result from the escape of plasma and white blood cells from defective blood vessels. They usually look greyish-white or yellowish and are circular or ovoid in shape. They are sometimes classified into three groups according to size: (1) punctate hard exudates, which often tend to coalesce. They are found in diabetic retinopathy, Coats' disease, etc.; (2) exudates of moderate size, such as 'cotton-wool or soft exudates' as, for example, in branch/central retinal vein occlusion, hypertensive retinopathy, etc. These 'exudates' have ill-defined margins and are actually areas of ischaemia containing cytoid bodies, unlike hard exudates which are generally lipid deposits; (3) larger exudates, as found in the severe forms of retinopathy.