Eyes

EYE
An eye is a round-shaped organ that works with the brain to provide us with vision. The shape of the eye is maintained by the pressure of the aqueous humor. The aqueous humor is the fluid that fills the front chamber of the eye.
Function of the Eye
The main function of the eye is to work with the brain to provide us with vision. The eye and brain translate light waves into a sensation we call vision.
Eye Parts
The eye has many parts. Some of the main parts are listed and described below.

• lens
o The transparent crystalline lens of the eye is located immediately behind the iris.
• cornea
o The cornea is a transparent dome which serves as the outer window of the eye. The cornea is the most powerful structure focusing light entering the eye.
• retina
o The retina is the innermost layer of the eye. It is composed of nerve tissue which senses the light entering the eye.
o The retina sends impulses through the optic nerve back to the brain, which translates the impulses into images that we see.
o There are 4 types of light-sensitive receptors found in the retina
1. rods
2. cones that absorb long-wavelength light (red)
3. cones that absorb middle-wavelength light (green)
4. cones that absorb short-wavelength light (blue)
• pupil
o The pupil is the hole in the center of the eye where light passes through.
• iris
o The iris is the colored part of the eye. It is a thin diaphragm composed mostly of connective tissue and smooth muscle fibers. The iris lies between the cornea and the crystalline lens.
• optic nerve
o The optic nerve is a continuation of the axons of the ganglion cells in the retina. It acts acts like a cable connecting the eye with the brain.
o The optic nerve is also called the cranial nerve II.
• sclera
o The sclera is the white, opaque portion of the eye. It provides protection and serves as an attachment for the extraocular muscles which move the eye.
Eye Doctor
An eye doctor is called an opthamologist. Periodic eye examinations by an opthamologist is the best defense against eye disease. You can also receive eye care from an optometrist or optician.
An optometrist is a college graduate who has received 4 years of training and is licensed to diagnose and treat vision problems and prescribe glasses and contact lenses.
An optician is a person trained to prepare and fit glasses after an opthamologist or optometrist has examined your eyes and prescribed vision correction.
Diseases/Conditions of the Eye
Some common conditions that afflict the eye are listed below.
• Glaucoma
• Farsightedness
• Nearsightedness
• Pink Eye
• Sty
• Blindness
• Astigmatism
• Tumors
• Infections
• Cataracts
• Dry Eye Syndrome
• Macular Degeneration
• Ectropion
• Entropion
• Bumps on the eyelid
Warning Signs of Eye Problems
• Difficulty adjusting to darkness
• Double vision
• Red eyes
• Crusty or swollen eyes
• Recurring pain in or around the eyes
• Excessive tearing or watering
• Very dry, itchy or burning eyes
• Loss of peripheral vision
• Dark spots in the center of your viewing area
• Change in color of the colored part of your eye
• Vision that suddenly becomes blurred or hazy