F

“F” selections in the Glossary of Terms for
Anatomy, Physiology & Pathology of the Human Eye

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photopsia; the brief perception of light that is purely subjective and accompanies a pathological condition, especially of the retina or brain

floaters

muscae volitantes; bits of optical debris (such as dead cells or fibrils), usually in the vitreous humor, that may be perceived as spots before the eyes

fluorescein angiography

a procedure in which a fluorescent yellow dye, injected into the vein of an arm, circulates into the eye within a few seconds, at which time a sequence of retinal photographs detect pooling of the dye in a certain location or leakage of the dye outside of blood vessels, confirming some type of retinal disorder

focal length

the distance away from a lens at which an image focuses, when parallel light rays enter the lens; the inverse, in meters, of the dioptric power of a lens

follicles

hyperplasia of the lymphoid tissue within the conjunctival stroma; resemble “Rice-a-Roni” embedded in the inferior conjunctiva; seen primarily in adenoviral and chlamydial infections, as well as in toxic reactions

fornix

the portion of the conjunctiva forming the junction between the posterior eyelid and the eyeball

fovea centralis

fovea; a small shallow depression or pit at the center of the macula, caused by an almost complete absence of inner retinal layers, containing only cones (and no rods) and which affords the most acute vision

foveola

the center of the fovea

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