The white part of your eyeball is called the sclera, and the black part is known as the pupil. The pupil performs like a camera shutter and controls the amount of light entering the lens and retina located behind it. When you visit an eye specialist, you should know an ophthalmologist is a medical doctor, whereas an optometrist has a doctorate in optometry.
Cornea
Collectively, the outer most layers covering the human eye are called the cornea. It is clear and has a dome shape. The cornea itself consists of five layers: epithelium, Bowman's layer, stroma, Descemet's membrane and the endothelium. The epithelium is the outermost layer of the human cornea; the endothelium is the innermost layer. The cornea protects the eye, shielding it from the most-damaging UV rays, dust and germs.
Cataracts can prevent light from coming through the cornea. This makes your vision cloudy. According to the Ohio State University Medical Center, the clouding of your sight "is caused when some of the protein which makes up the lens begins to clump together and interferes with vision." At first the cataract might not cause a problem, but can it deteriorate vision over time as the cataract grows.
Nearsightedness
People with 20/20 vision see objects clearly at a distance of 20 feet. A diagnosis of nearsightedness means your vision blurs when you look at something far away. According to the National Institutes of Health, NIH, this condition commonly develops during youth, progresses with age and requires regular changes to eyeglass prescriptions.
Farsightedness
If you are having difficulty seeing objects up close, you may be farsighted. The NIH explains farsightedness is frequently a congenital visual condition; it's present at birth. However, farsightedness is often temporary, and many children outgrow the condition. Children often do not require corrective lenses if the condition is mild to moderate.
Protection
Critical to preventing human eye injuries, protect your eyes at home, work and play. According to the Department of Ophthalmology and Visual Sciences at the University of Illinois at Chicago, UIC, of the more than 1 million eye injuries annually, 42,000 require hospitalization. There are 1,000 eye injuries incurred at work every day, but the UIC warns eye injury due to the misuse of household products is more common.
Prevention
To prevent an injury to your eyes, the UIC recommends clearing rocks and debris before mowing the lawn, keeping glass and sharp objects out of the hands of children and to not peer into a bag of popcorn fresh from the microwave. The UIC advises the use of safety glasses when you use strong chemicals like oven cleaner, chop wood, use power tools or jump start a car.
Infection
Viruses, fungi and bacteria all cause infections in the human eye. Different parts of the eye contract infections, and your condition may or may not spread to the other eye. The NIH says eye infection symptoms include redness, itching, discharge, vision problems, swelling and pain. Conjunctivitis, also known as pink eye, is a common and highly contagious eye infection.
References
- National Institutes of Health: Normal, Nearsightedness, and Farsightedness
- National Institutes of Health: Eye Infections
- The Ohio State University: What is a Cataract?
- Department of Ophthalmology and Visual Sciences at the University of Illinois at Chicago
- Virginia Commonwealth University: How Does the Eye Work?
