The Human Eye
How the Human Eye Works
There are many similarities between the
functioning of a camera and the way the
human eye works. Both rely upon refraction
and lenses to form images. To capture and
record an image, the eye's cornea first
gathers light and bends it through the
pupil, much as a camera's lens and
diaphragm control the light coming in on
its way to being recorded on film. Both
create images that are real and inverted,
handled by the camera lens and the
eye's lens. Then the light is "recorded" on
the retina of the eye, which is a system of
rods and cones that convert the image to
electrical impulses that are sent along the
optic nerve to the brain, much as light is
recorded on film in a camera.
How a camera lens works
Actually, there are three parts of the eye
that control light refraction -- the aqueous
humor, a liquid on top of the lens, the lens
itself, and the vitreous humor, the jelly-like
substance that fills the space between the
lens and the retina.
The center of the retina is called the
macula, which is responsible for sharp
vision, such as reading vision. If the macula
is seriously damaged, vision is irreparably
impaired. All in all, the system of parts in
the eye works remarkably to provide vision
in healthy individuals.
Click here: Vision Problems in the U.S.
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Eye Diseases and Disorders
Arizona Foundation for Eye Health (AFEH) is poised to help bring important eye data and educational information to alert all Arizonans of the need to be proactive in caring for their eye health to prevent blindness and vision loss.
The following current and accurate information has been provided to AFEH by the Kellogg Eye Center at the University of Michigan.
Age-Related Macular Degeneration (AMD)
Age-Related Macular Degeneration (AMD) is a degenerative eye disease that causes damage to the macula (central retina) of the eye. AMD is the leading cause of vision loss . . . more.
Amblyopia
Amblyopia, sometimes called a "lazy eye," occurs when one or both eyes do not develop normal vision during early childhood. Babies are not born with 20/20 vision . . . more.
Astigmatism
Astigmatism usually occurs when the front surface of the eye, the cornea, has an irregular curvature. Astigmatism is one of a group of eye conditions known as refractive errors. . . more.
Cancer (Intraocular Melanoma)
Intraocular melanoma, a rare cancer, is a disease in which cancer (malignant) cells are found in the part of the eye called the uvea. The uvea contains cells called melanocytes . . . more.
Cataract
A cataract is a clouding of the eye's lens. The vast majority of cataracts are related to age. Most people do not even realize they have a cataract, as cataracts grow very slowly . . . more.
Conjunctivitis
Conjunctivitis is inflammation of the conjunctiva or thin membrane covering the white of the eye and the inner surface of the eyelid. The inflamed conjunctiva will usually make the eye appear red or pink . . .more.
Diabetic Retinopathy
Diabetes can affect sight by causing cataracts, glaucoma, and most importantly, damage to blood vessels inside the eye, a condition known as "diabetic retinopathy". Diabetic retinopathy is a complication of diabetes that is caused by changes in the blood vessels . . . more.
Dry Eye
A condition known as dry eye syndrome occurs when tear film abnormalities prevent the eyes from being comfortable . . . more.
Floaters
Small specks or clouds moving in your field of vision are called floaters. You may see them more clearly when looking at a plain background. . . more. |
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Glaucoma
Glaucoma is a group of eye diseases causing optic nerve damage. The optic nerve carries images from the retina, which isthe specialized light sensing tissue, to the brain . . . more.
Graves Disease
Graves disease (hyperthyroidism) is a medical condition in which an overactive thyroid gland secretes an excess amount of thyroid hormone . . . more.
Hyperopia (Farsightedness)
Hyperopia, also known as farsightedness, is usually inherited. Children are often hyperopic which may lessen as an adult. Hyperopia is a refractive error . . . more.
Myopia
Myopia, also known as nearsightedness, is inherited and is often discovered in childhood. Myopia is a refractive error, which results from a disorder rather than from disease . . . more.
Presbyopia
Presbyopia (aging of the lens in the eye and the muscles that control the shape of the lens) commonly occurs after age 40, when the lens of the eye becomes more rigid . . . more.
Retinitis Pigmentosa
Retinitis Pigmentosa (RP) refers to a group of diseases which cause a slow but progressive vision loss. In each of them there is a gradual loss of the light-sensitive retinal cells called rods and cones . . . more.
Retinopathy of Prematurity (ROP)
Retinopathy of prematurity (ROP) occurs in premature babies when abnormal blood vessels and scar tissue grow over the retina . . . more.
Strabismus
Strabismus is a visual disorder where the eyes are misaligned and point in different directions. This misalignment may be constantly present, or it may come and go. Sometimes, only one eye is affected . . . more.
Ushers Syndrome
Ushers syndrome is a form of Retinitis Pigmentosa (RP), with associated deafness. Ushers syndrome is the cause of approximately 10% of all hereditary deafness . . . more.
Uveitis
Uveitis means "inflammation of the uvea", or the middle layer of the eye. The uvea consists of three structures: the iris, the ciliary body, and the choroid . . . more.
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