Eye Health Fact Sheet For K-12 Students

Nearsightedness

Nearsightedness, also known as myopia, is a very common visual state. Close objects are viewed as clear, while far objects are viewed as blurry. Many people with nearsightedness constantly squint, have trouble seeing the tv or a chalkboard in a classroom, and hold books very close to their face. The constant squinting may cause eye pain and/or headaches. (1)

Nearsightedness is a refractive error. This means when light rays enter the eye, instead of focusing right on the retina and getting good vision, the rays focus at another point in the eye. When someone has nearsightedness, the light rays focus before the retina. Objects far away become blurry. Wearing glasses or contact lenses are good and straightforward ways to correct nearsightedness. (2)

Farsightedness

Farsightedness, also known as hyperopia, is a very common visual state. Distant objects are viewed as clear, while near objects are viewed as blurry. Many people with farsightness constantly squint to see near objects in relative clarity. Doing ordinary activities that need close reading or writing may cause eye pain and/or headaches.(3)

Farsightedness is a refractive error. This means that when light rays enter the eye, instead of focusing right on the retina and getting good vision, the rays focus at another point in the eye. When someone has farsightedness, the light rays focus behind the retina. Close objects become blurry. Wearing reading glasses can correct farsightedness.(4)

Color Blindness

Color blindness is defined as inability to tell certain colors apart. Most people who have some sort of color blindness are unable to determine the difference between red and green. A few people are unable to tell blue and yellow apart.  A small number of people are unable to tell any colors apart. Color blindness can be diagnosed through non-invasive tests like looking at multicolored dots and patterns; people with color blindness have trouble picking out specific shapes or numbers embedded in the dots and patterns.(5)

There are many causes of color blindness. It is an inherited disease, and men are more likely to have color blindness than women.  Some diseases, such as diabetes or general eye ailments, may cause poor color vision. Certain medications may also have a role in developing poor color vision. There is no treatment for color blindness.(6)

Amblyopia

Amblyopia is commonly known as “lazy eye”.  One eye has stronger vision and the other eye has weaker vision. Vision may be poor, and depth perception may be hindered. The brain, after a certain amount of time, may disregard signals from the weaker eye.(7)

Amblyopia can be caused by strabismus, a term for imbalance in the muscles that position the eyes. Size differences and/or abnormal eye shape can also cause “lazy eye”.  It is best to start treatment as soon as possible in early childhood so as to prevent permanent visual impairment.  A common treatment is to place an eye patch over the better eye to help the weaker eye become stronger. Glasses or contacts may also help the eye condition.  Surgery may be an option for severe cases.(8)

Strabismus

Strabismus is caused by a lack of synchronization between the eyes, making one eye misaligned with the other.  The eyes are unable to focus on one point at the same time. Physically, the eyes look as if they are looking in different directions.  Other symptoms consist of double vision, lack of depth perception, and/or vision in only one eye.(9)

Treatment of strabismus centers on making the eye muscles stronger. Eye muscle exercises are used to strengthen the eye muscles. A patch may be put on the stronger eye to help build up the weaker eye if there is an obvious disparity between the eye strengths. Glasses or surgery may also be used to help treat strabismus.(10)

Nystagmus

Nystagmus is characterized by uncontrolled and back and forth eye movement. One or both eyes may be afflicted. The unintentional eye movement is caused by irregular functions in the brain that play a part in general eye movement. If brain areas that control eye movement are damaged, uncontrolled eye movement will likely ensue. The eye disorder may be congenital (present at birth) or obtained later on in life. There is no cure for most cases of nystagmus.(11)

Conjunctivitis

Conjunctivitis is commonly known as “pink eye”. One or both eyes may be afflicted with conjunctivitis. The conjunctiva, the lining on the eyelid and part of the eyeball, becomes inflamed and/or infected. Redness, itchiness, discharge, and general discomfort are all symptoms of conjunctivitis. The eye ailment is usually caused by bacteria or viruses. (12)

There are different treatments for different kinds of “pink eye.” If the conjunctivitis is bacterial, antibiotic eyedrops are usually prescribed. If the conjunctivitis is viral, the patient should see a general clearing up of the ailment without any kind of specific action. Because conjunctivitis can be passed to others, it may be a priority to avoid close contact with others while having the symptoms.(13)

Cataracts

A cataract is a clouding of the clear lens in the eye. Developing at a slow rate, the cataract starts off small and gradually takes over the whole lens. Images become more and more blurred, and vision becomes increasingly impaired. A cataract causes no pain to the eye, but symptoms include blurred vision, increased sensitivity to light, halos around lights, and fading of bright colors.(14)

Cataracts are a common eye ailment. About half of all Americans develop some sort of cataract by age 65, and some children develop cataracts as well. Diabetes, previous eye surgeries/injuries, high exposure to sunlight, and family history of cataracts are some other risk factors.(15)

Cataracts can be diagnosed by a simple eye exam. However, the removal of cataracts is trickier. The treatment for a cataract is surgery to replace the clouded lens with a lens implant. The surgery is short and the recovery process is minimal.(16)

How glasses correct vision:

Contrary to popular belief, the eye does not simply see objects. The eye is actually a specialized structure that takes in light rays. Light strikes the eye on the cornea, the outer surface of the eye. Light travels through the lens, a structure that precisely focuses the light to hit the retina. In order to have clear vision, the light needs to focus exactly on the retina. If the cornea or lens is positioned in a way that does not allow light to correctly hit the retina, one will suffer from blurry vision. Refractive error is the technical term. (17)

Glasses are the most common way to correct refractive error. Contact lenses and laser eye surgery are also popular options. All of these corrective measures help light rays focus correctly on the retina.  Glasses help vision by adjusting the focusing power of the cornea and the lens. Contact lenses work the same way. Laser eye surgery changes the shape of the cornea by removing a small portion of the middle layer of the cornea.(18)

 

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Footnotes

(2) Ibid.

(4) Ibid.

(6) Ibid

(8) Ibid.

(9) Fact Sheet: Strabismus. National Institute of Health. http://www.nlm.nih.gov/medlineplus/ency/article/001004.htm. Accessed April 28, 2009.

(10) Ibid.

(11) Fact Sheet: Nystagmus. National Institute of Health. http://www.nlm.nih.gov/medlineplus/ency/article/003037.htm. Accessed April 28, 2009.

(13) Ibid.

(15) Ibid.

(16) Ibid.

(17) Lewis, Carol. “Vision Correction: Taking a Look at What’s New.” FDA Consumer. Sep. 2001.

(18) Ibid.