By printing and/or reading this article, you agree that you accept all terms and conditions of use, as specified online. The Eye As we look around us every day, the ability to see our world is something we may not think much about, until something goes wrong. About 120 million people in the U.S. wear eyeglasses or contact lenses to correct vision problems, according to the National Eye Institute (NEI). (Read about " Refractive Errors") Many others suffer from more serious problems and/or diseases that affect their ability to see, such as glaucoma, macular degeneration or cataracts. (Read about "Glaucoma" "Macular Degeneration" "Cataracts") Eyesight is not something to take for granted. It depends on many different parts working together to form our vision. The basic parts of the eye, according to the American Optometric Association (AOA) include: eyelids - help protect the eye conjunctiva - this is what lines the eyelid cornea - the clear covering on the front of the eye sclera - the white of the eye iris - the colored part of the eye that helps control the amount of light that enters pupil - the hole in the center of the iris that is dark lens - focuses the light onto the back of the eye retina - the layer of nerves in the back of the eye, made up of rods and cones macula - a section of the retina near the center that lets us see fine details optic nerve - sends an electrical signal to the brain How does all this work together? Light hits an object and bounces off. That reflected light enters the eye through the cornea. The cornea acts like a window and works with the lens to focus the light. The iris opens and closes, which adjusts the size of the pupil, to control how much light gets in. The light then hits the retina in the back of the eye, with its millions of light-sensing cells, the rods and cones. At this point, the light is changed into an electrical signal and sent through the optic nerve to the brain (Read about "The Brain" "Nervous System"), which converts that signal into an image it can understand. It works very much like a camera and film. The eye's cornea and lens are like the lens of a camera, which focus on an object. The retina is like the film where the image is laid down and the brain develops the picture. One way you can help protect your eyesight is through regular eye exams. (Read about "Eye Exams") Another is by learning all you can about your eyes and the problems that can affect them. By following the links below, you can find more eye topics of interest. Amblyopia: see Amblyopia Astigmatism: see Refractive Errors Bell's palsy: see Bell's Palsy Blepharitis: see Blepharitis Blepharospasm: see Blepharospasm Cancer, eye: see Eye Cancer Cataracts: see Cataracts Computer eyestrain: see Computers and Health Conjunctivitis: see Conjunctivitis Corneal dystrophies: see Corneal Dystrophies Diabetic retinopathy: see Diabetes Dry eye: see Dry Eye Eyes and sun: see Eyes and Sun Eye cancer: see Eye Cancer Eye exams: see Eye Exams Eye patching: see Amblyopia Farsightedness: see Refractive Errors Fuchs' dystrophy: see Corneal Dystrophies Glaucoma: see Glaucoma Glossary of Vision Terms: see Glossary of Vision Terms Herpes, ocular: see Ocular Herpes Hyperopia: see Refractive Errors Inflammation: see Uveitis Injuries: see Eye Injury Keratitis: see Keratitis Keratoconus see Corneal Dystrophies Lattice dystrophy: see Corneal Dystrophies LASIK: see Refractive Errors Lazy eye: see Amblyopia Low vision: see Low Vision Macular degeneration: see Macular Degeneration Macular hole: see Macular Hole Map-dot-fingerprint dystrophy: see Corneal Dystrophies Migraine, ophthalmoplegic: see Migraine Headaches Myopia: see Refractive Errors Nearsightedness: see Refractive Errors Ocular herpes: see Ocular Herpes Ocular larva migrans (OLM): see Toxocariasis Pink eye: see Conjunctivitis Presbyopia: see Refractive Errors Refractive errors: see Refractive Errors Retinal detachment: see Retinal Detachment Retinitis pigmentosa: see Retinitis Pigmentosa Retinoblastoma: see Cancer and Children Retinopathy, diabetic: see Diabetes Retinopathy of prematurity (ROP): see Retinopathy of Prematurity Retrolental fibroplasia: see Retinopathy of Prematurity Shingles: see Shingles Sjögren's syndrome : see Sjögren's Syndrome Sun and eyes: see Eyes and Sun Toxocariasis: see Toxocariasis Toxoplasmosis: see Toxoplasmosis Tunnel vision: see Retinitis Pigmentosa Usher syndrome: see Usher Syndrome Uveitis: see Uveitis Vision terms: see Glossary of Vision Terms All Concept Communications material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns. © Concept Communications Media Group LLC Online health topics reviewed/modified in 2008 | Terms of Use/Privacy Policy By printing and/or reading this article, you agree that you accept all terms and conditions of use, as specified online. Copyright © St. Joseph Healthcare | Privacy Statement