How does the eye work?
 

Your eye works like a camera. The white part on the outside of the eyeball is called the sclera. In its center is the cornea, the transparent part of the eye that covers the iris or colored part of the eye. The iris operates like a camera shutter by controlling the amount of light that enters the eye.

Located behind the iris is the eye lens. It is suspended by fibers that tighten or loosen to focus the light rays from objects outside the eye onto the retina, located at the back of the eye.

The vitreous chamber, made up of clear, gelatinous fluid, is the space between the lens and the retina. The retina is like film in a camera. Within its layers are the cells that perceive light and color. The images received by the retina are conveyed to the brain by the optic nerve, allowing us to see objects.

An ophthalmologist is a physician who specializes in comprehensive eye care. Ophthalmologists can examine, diagnose and treat eye disorders. They are skilled in all facets of eye care, from prescribing eye glasses to performing intricate eye surgery. Ophthalmologists receive four years of medical school after college, a year’s internship, and a three-year residency.

Optometrists have a doctorate in optometry, not a medical degree. They’re skilled professionals who test vision and prescribe eyeglasses, contacts and other optical wear, such as low vision devices. Most  optometrists have received additional training and specialize in treating patients with low vision or who require spectacles or contact lenses for correction.

Opticians have received additional training following college. They fill prescriptions and help fit patients into glasses and contacts.

How often should I have an eye exam?

You should schedule regular eye exams with an ophthalmologist or optometrist because many eye disorders exhibit no warning symptoms, but are treatable when discovered in the early stages. Here is a general guide:

Before 20 years of age— as recommended by your pediatrician or eye doctor

Ages 20-39— at least once during this period

Ages 40-64— every two to four years

65 or older— every one to two years

African Americans and Native Americans— Since you’re at a greater risk of developing glaucoma, visit your eye doctor every three to five years before age 40 and every two years thereafter.

Diabetic patients— Have your eye examined every year to prevent vision loss from diabetes-related eye disorders.

If you are diagnosed with a blinding disease, seek treatment from an ophthalmologist who specializes in treating your condition.
 

           What does an eye doctor do during an exam? 

— Review your family history of eye health.

— Determine your visual acuity.

— Check your intraocular pressure.

— Examine the response of your pupils to light.

— Dilate your eyes and examine the posterior structures of the eye (the back of the eye, including the retina and optic nerve).

— If indicated, perform a variety of specialized tests.

Will poor lighting hurt my eyes?

No. Poor lighting won’t hurt your eyes when you read or watch television. However, a good source of light will lessen the strain on your eyes.

Will my computer harm my eyes?

There is no scientific evidence that computer screens emit hazardous radiation. But you can suffer eye strain or fatigue from extended computer use, poor lighting or a variety of other related causes.

What do I do if I injure my eye?

If you receive an eye injury, seek immediate medical attention from an ophthalmologist or primary care physician to reduce the risk of permanent damage. Following are some general guidelines for treating eye injuries properly.

For cuts:

• Bandage the eye gently.
• Be careful not to rub or apply too much pressure on the eye.
• Don’t wash out the eye or remove particles in the eye.
• Seek medical attention immediately if the cut shows signs of infection.

For foreign particles:

• Pull upper lid down onto lower lid and let lower lashes sweep the particle away.
• Blink repeatedly until the particle goes away; try not to rub.
• Seek medical attention if the above steps don’t work or if the material scratches your cornea.

For chemical splashes:

• Use your fingers to separate lids, then wash the eye with water from a faucet or clean container.
• Continue washing for several minutes while rolling your eyeball.
• Don’t cover your eye with a bandage.
• Seek immediate medical attention.

Blows to the eye:

• Gently apply an ice compress to reduce swelling and ease the pain.
• Seek immediate medical attention.

Common sense tips for preventing eye injuries:

• When spraying chemicals, make sure the nozzle is pointed away from your face.
• Use a shield over the pan when frying foods.
• Wear safety goggles when using power tools, welding equipment or tools that spark or flame, poisonous chemicals, gardening equipment, etc.
• Supervise children when playing with dangerous toys or games, such as pellet guns, fireworks, etc.
• Wear protective eyewear when playing sports such as racquetball, baseball, basketball or tennis.
• Wear latex gloves (powderless) when cutting up hot peppers so that the oils do not transfer to eyes or contact lenses. 

With appreciation for guidance from the Dictionary of Eye Terminology, Second Edition. (1990) Barbara Cassin and Sheila A.B.Solomon. Melvin L. Rubin, M.D., Editor (Triad Publishing Company, Gainesville, Florida)
and Emory University.