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Gullstrand, Allvar

(Encyclopedia)Gullstrand, Allvar älˈvär gŭlˈstränd [key], 1862–1930, Swedish ophthalmologist. He was professor (1894–1927) successively of eye therapy and of optics at the Univ. of Uppsala. He applied the...

retina

(Encyclopedia)retina: see vision; eye. ...

tears

(Encyclopedia)tears, watery secretion of the lacrimal gland, which is located at the outer corner of the eye socket immediately above the eyeball. Tearing, or lacrimation, is a continuous and largely involuntary pr...

vision

(Encyclopedia)CE5 Optic nerve vision, physiological sense of sight by which the form, color, size, movements, and distance of objects are perceived. Defects of vision include astigmatism, color blindness, far...

Hartline, Haldan Keffer

(Encyclopedia)Hartline, Haldan Keffer, 1903–83, American physiologist, b. Bloomsburg, Pa., M.D. Johns Hopkins, 1927. From 1931 to 1949 (except for 1940–41), he was a researcher at the Eldridge Reeves Johnson Fo...

nearsightedness

(Encyclopedia)nearsightedness or myopia, defect of vision in which far objects appear blurred but near objects are seen clearly. Because the eyeball is too long or the refractive power of the eye's lens is too stro...

guide dog

(Encyclopedia)guide dog, a dog trained to lead a blind person. The first school for training such dogs was established by the German government after World War I for the benefit of blinded veterans. Schools now exi...

blindness

(Encyclopedia)blindness, partial or complete loss of sight. Blindness may be caused by injury, by lesions of the brain or optic nerve, by disease of the cornea or retina, by pathological changes originating in syst...

Zaleucus

(Encyclopedia)Zaleucus zəlo͞oˈkəs [key], fl. c.650 b.c., Greek lawgiver of Locris, in Italy. According to tradition, his was the earliest codification of Greek law. References to Zaleucus' code, which was widel...

stereoscope

(Encyclopedia)stereoscope stĕrˈēəskōpˌ [key], optical instrument that presents to a viewer two slightly differing pictures, one to each eye, to give the effect of depth. In normal vision the two eyes, being a...