How do eyelids protect your eyes

The eyes are one of the most vulnerable parts of our body due to their exposure to the outside. The eyelids are responsible for protecting their surface against foreign elements or other stimuli that could damage them. In addition, each time we blink our eyes receive a set of substances that moisten them and prevent them from drying out. Each cone type is sensitive to one of three different colors — red, green, or blue — to help you see different ranges of color. Together, these cones can sense combinations of light waves that enable our eyes to see millions of colors.

Rods and cones process the light to give you the total picture. You're able to see that your friend has brown skin and is wearing a blue hat while he tosses an orange basketball. Sometimes someone's eyeball shape makes it difficult for the cornea, lens, and retina to work perfectly as a team.

When this happens, some of what the person sees will be out of focus. To correct this fuzzy vision, many people, including many kids, wear glasses. Glasses help the eyes focus images correctly on the retina and allow someone to see clearly. As adults get older, their eyes lose the ability to focus well and they often need glasses to see things up close or far away. Most older people you know — like your grandparents — probably wear glasses. Think of the optic nerve as the great messenger in the back of your eye.

The rods and cones of the retina change the colors and shapes you see into millions of nerve messages. Then, the optic nerve carries those messages from the eye to the brain! The optic nerve serves as a high-speed telephone line connecting the eye to the brain.

When you see an image, your eye "telephones" your brain with a report on what you are seeing so the brain can translate that report into "cat," "apple," or "bicycle," or whatever the case may be. For crying out loud, the eye has its own special bathing system — tears! Above the outer corner of each eye are the lacrimal say: LAK-ruh-mul glands , which make tears.

Every time you blink your eye, a tiny bit of tear fluid comes out of your upper eyelid. It helps wash away germs, dust, or other particles that don't belong in your eye. Tears also keep your eye from drying out. Then the fluid drains out of your eye by going into the lacrimal duct this is also called the tear duct. You can see the opening of your tear duct if you very gently pull down the inside corner of your eye.

When you see a tiny little hole, you've found the tear duct. Your eyes sometimes make more tear fluid than normal to protect themselves. This may have happened to you if you've been poked in the eye, if you've been in a dusty or smoking area, or if you've been near someone who's cutting onions. And how about the last time you felt sad, scared, or upset? Your eyes got a message from your brain to make you cry, and the lacrimal glands made many, many tears. Reviewed by: KidsHealth Medical Experts.

In our vision system, glands secrete liquids and lubricants. Meibomian glands , for instance, secrete oil to lubricate the surface of the eye. These glands in the tarsus help prevent evaporation of tears. Glands in the eyelids also secrete oil around the follicles of the eyelashes and release sweat for evaporative cooling. What about the tear glands?

Most tears come from the lacrimal glands , which start a job that the eyelids finish. Tear ducts carry away excess tears into the nasal cavity this is why crying gives you a runny nose. It takes a lot of nerves to make your eyes blink properly. These nerves direct movement and provide sensation:. Three kinds of motor nerves send signals from the central nervous system that make the eyelids open and close.

Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. American Academy of Ophthalmology. Parts of the eye. December 21, Front Neurol. Updated October 21, Updated February 8, Updated November 24, How to stop eye twitching. July 27, Updated October 22, National Institute of Neurological Disorders and Stroke. Bell's palsy fact sheet. Updated March 13, Your Privacy Rights. To change or withdraw your consent choices for VerywellHealth.

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