…an item of illustrative matter, such as a film, slide, or model, designed to supplement written or spoken information so that it can be understood more easily…
…an imaginary line representing the path of light from an object to the eye…
…sharpness of vision, measured by the ability to discern letters or numbers at a given distance according to a fixed standard…
…the angle formed at the eye by rays from the extremities of an object viewed…
…a binary star of which the components are sufficiently far apart to be resolved by an optical telescope…
…the part of the cerebral cortex that receives and processes sensory nerve impulses from the eyes…
…a purplish-red light-sensitive pigment present in the retinas of humans and many other animal groups…
…a condition in which a person can see but cannot recognize or interpret visual information, due to a disorder in the parietal lobes…
…a device for displaying input signals as characters on a screen…
…an item of illustrative matter, such as a film, slide, or model, designed to supplement written or spoken information so that it can be understood more easily…
…using both sight and sound, typically in the form of images and recorded speech or music…
