focal distance

fo·cal dis·tance

the distance from the center of a lens to its focus.

fo·cal dis·tance

(fō'kăl dis'tăns)

The distance from the center of a lens to its focus.

focal distance

In ophthalmology, the distance from the optical center of a lens to the focal point.

See also: distance

focal

1. limited to a small area or volume.

2. pertaining to or emanating from focus.

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focal distance

see focal-film distance.

focal length

the distance between the lens and an object from which all rays of light are brought to a focus.

focal liver disease

widely disseminated micro-abscesses or abscesses, migration paths of helminth larvae.

focal macular melanosis

dark colored spots on the skin, not elevated above the skin surface but apt to be confused with melanosis.

focal myelitis-encephalitis

widely disseminated inflammatory lesions, usually the result of blood-borne infection, in brain and spinal cord.

focal symmetrical encephalomalacia

see focal symmetrical encephalomalacia.

focal symmetrical spinal poliomalacia

see focal symmetrical spinal poliomalacia.

focal ulcerative dermatitis

manifest by ulcers in the unfeathered anterior breast skin of 4 to 5 months old male turkeys. The incidence is influenced by litter type. Called also breast buttons.

focal zone

in ultrasound, the area of the transducer where the sound beam is most sharply focussed and where the area under examination will give the best image.