PLTW: HBS - 2.4, 2.4.3 Put Yourself in Someone Else's Eyes (Key Terms), 2.4.1- Exploring the Anatomy of the Eye, 2.4.2- Visual Perception

Aqueous Humor

A clear, watery fluid that fills the space between the cornea and iris.

Myopia

A condition in which the visual images come to a focus in front of the retina of the eye because of defects in the refractive media of the eye or of abnormal length of the eyeball resulting especially in defective vision of distant objects -- called also nearsightedness.

Hyperopia

A condition in which visual images come to a focus behind the retina of the eye and vision is better for distant than for near objects - called also farsightedness.

Lens

A curved piece of glass or plastic used singly or combined in eyeglasses or an optical instrument (as a microscope) for forming an image by focusing rays of light.

Vitreous Humor

A thick, gelatinous fluid found in the posterior segment of the eye (between the lens and the retina).

tapetum

Allows animals who are active in low light to have the light reflect off the back of the eye and bounce around inside the eyeball.

Glaucoma

An abnormal condition of elevated pressure within an eye.

Cataracts

Clouding of the lens of the eye.

Retinitis Pigmentosa

Genetic disease of light sensitive cells in retina - progressive night blindness, peripheral vision, total blindness

Myopia (Near Sightedness)

Lens focuses object in front of retina - can see near objects well but not not far away objects

Cone

Localized photosensitive receptor cells that function in color vision and detail.

Astigmatism

Misshapen lens resulting in a blurred and imperfect image.

Rod

Photosensitive receptors found in much of the retina responsible for seeing motion, black/white.

Iris

Pigmented part of the eye that surrounds the pupil and determines how much light to let in to the eye.

Photoreceptors

Rods and Cones

red-green colorblindness

Sex linked trait that usually results in males who are dependent on only their blue cones, as the others do not function.

Depth Perception

The ability to judge the distance of objects and the spatial relationship of objects at different distances.

Accommodation

The automatic adjustment of the eye for seeing at different distances affected chiefly by changes in the convexity of the crystalline lens.

Optic Nerve

The connection between the eye itself and the brain.

Refraction

The deflection from a straight path undergone by a light ray or a wave of energy in passing obliquely from one medium (as air) into another (as water or glass) in which its velocity is different.

Pupil

The opening in the iris, which admits light into the interior of the vertebrate eye; muscles in the iris regulate its size.

six muscles per eye

The reason that humans can roll their eyes and cows can't.

Retina

The sensory membrane that lines most of the large posterior chamber of the vertebrate eye and functions as the immediate instrument of vision.

Blind Spot

The small circular area in the retina where the optic nerve enters the eye that is devoid of rods and cones and is insensitive to light.

Cornea

The transparent part of the coat of the eyeball that covers the iris and pupil and admits light to the interior.

ciliary muscles

These are used to change the shape of the lens.

detached retina

This could happen if the pressure inside the eye was not high enough to keep the retina in place.

optomitrist

Trained to do vision tests and diagnose eye issues especially those needing corrective lenses. Can not do surgery.

optician

Trained to verify and fit eyeglasses

convergent

Type of lens used to correct hyperopia

divergent

Type of lens used to correct myopia

Glaucoma

a buildup of internal eye pressure (intraocular pressure) - can damage the optic nerve, blurred vision on edges or blindness

Aqueous Humor

a clear fluid that helps the cornea keep its rounded shape

Cornea

a tough, clear covering over the iris and pupil that helps protect the eye. Light bends as it passes through

Color Perception Deficiency

any of the three types (red, blue, green) of cones that don't work

Cataracts

as one ages, proteins in the lens clump together and start to cloud the lens - surgery to replace lens

Fovea Centralis

center of macula and is the region of the greatest visual acuity

Lens

clear, flexible structure that makes an image on the eye's retina

cone cells

concentrated at the center of the retina in an area called macula lutea

Astigmatism

condition in which the cornea or lens is irregularly shaped

macula

contains no rods and is responsible for sharp, colorful images

Optical Illusions

deceptive, self-contradictory, and misleading images

Macular Degeneration

degeneration of the macula (part of the retina possible for vision - central vision affected (not really seeing things) spot in the middle of vision they can't see

Hyperopia

farsighted eye is too short glasses (+) prescription convergent (convex)

Cones

function in bright light and provide sharp, colorful daylight images

Rods

function in dim light and perceive shades of gray

Color Blindness

lack of certain type of cone - certain colors are hard to differentiate

Retina

layer of light-sensitive cells at the back of the eye. It detects images focused by the cornea and lens. It's connected to the brain by the optic nerve.

Hyperopia (far sighted)

lens focuses object beyond/behind the retina - can see far away objects well, but not near objects

Near Point

minimum distance which the eye can focus

Iris

muscle that controls how much light enters the eye

Myopia

nearsighted eye is too long glasses (-) prescription divergent (concave)

blind spot

no photorecepters

Emmetropia

normal eye vision

Afterimage

optical illusion that occurs when looking away after staring intently at certain images or colors

Tapetum

shiny material behind retina, not found in humans

Things that effect optical illusions

surrounding objects, intense colors, distortions, preconceptions

Depth Perception

the ability to judge the relative distance between objects in three dimensions

Peripheral Vision

the ability to see things that fall outside the direct line of vision. Controlled by rods

Visual Activity

the amount of detail the eye can distinguish

Optic Nerve

the bundle of nerve fibers that carry information from the retina to the brain

Accommodation

the combination of reflexive actions by which the lens of the eye changes to keep the focal length constant

Pupil

the dark circle in the center of your iris. It's a hole that lets light into the inner eye

blind spot

the point at which the optic nerve leaves the eye, light cannot be stimulated

sclera

the toughest part of the eye, also known as the "whites" of the eye.

red, green, blue

the types of cones in humans

Vitreous Humor

thick, clear jelly that gives the eyeball it's shape

Scelra

thick, white outer covering of eyeball