vocab 10/5-10/9

accommodation

adjustment by the eye seeing at different distances, accomplished by changing the shape of the crystalline lens through action of the ciliary muscle

near point accommodation

nearest point at which the eye can perceive an object distinctly. It varies according to the power of accommodation

near point convergence

nearest single point at which the two eyes can direct their visual lines

dark adaptation

ability of the retina and pupil to adjust to a dim light

light adaptation

power of the eye to adjust itself to variations in the amount of light

Photopic vision

pertaining to vision in light-adapted conditions, mainly a cone function

Scotopic vision

vision in law light levels that involves rod photoreceptors

Rhodopsin (visual purple)

A pigment in the outer layers of the retina, a photo chemical substance mediating light onto nerve impulses

iodopsin

the light-sensitive photopigment located within the cone cells of the retina

field of vision aka visual field

entire area that can be seen without shifting the eye

scotoma

an area of reduced or lost vision in the visual field

arcuate scotoma

characteristically arc-shaped area of blindness in the field of vision; caused by interruption of a nerve fiber bundle in the retina; most often seen in glaucoma

altitudinal hemianopia

blindness of either the upper of the lower half of the visual field

bitemporal hemianopia

involves the temporal halves of the visual fields of both eyes

homonymous hemianopia

one-half of the visual field on the same side in both eyes

quardrantanopia

blindness or loss of vision in a quarter sector of the visual field of one or both eyes

nasal step

depression of the nasal peripheral portion of the field. sign of glaucoma

kinietic perimetry

type of visual field test in which stimuli are moved from non-seeing area until they are first perceived

automated perimetry

instrument. maps field of vision by presenting stationary luminous stimuli in pre-arranged locations, plotted by computer

threshold static perimetry

the type of static perimetry in which the threshold is that level of brightness at which the pt can just detect a test object about half the time

color vision

function. results from stimulation of red, green, and blue cone receptors in the retina

color deficiency

diminished ability to perceive differences in color; usually reds and greens, rarely blues and yellows

ishihara test

a test of detecting defects in recognizing colors, based on the tracing of numbers or patterns in a series of multicolored charts or plates

suppression

the r