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Fact Sheet

Nearsightedness

Nearsightedness, also known as myopia, is the most common visual problem among students. Close objects are viewed as clear while far objects are viewed as blurry. Many students with nearsightedness constantly squint, have trouble seeing the 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. When light rays enter the eye, instead of focusing 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, making images of far-away objects blurry. Wearing corrective lenses is the most popular and straightforward way to correct nearsightedness. (2)

Farsightedness

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

Like nearsightedness, farsightedness is a refractive error, however instead of light rays focusing before the retina, light rays focus behind the retina. Close objects become blurry. Wearing corrective lenses is the most popular and straightforward way to correct farsightedness.(4)

Color Blindness

Color blindness is defined as incapacity to tell certain colors apart. Most people who have some sort of color blindness are unable to tell red and green apart.  Although it is somewhat rare, there are cases of colorblindness in which people cannot tell blue and yellow apart.  Rarer still are those that are unable to tell any colors apart. Color blindness can be easily 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 possible causes of color blindness. It is an inherited disease, and men are more likely to have color blindness than women.  Other diseases can cause colorblindness as a side effect, such as diabetes or general eye ailments.  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” because one eye has stronger vision than the other. Over time, the brain may begin to disregard signals from the weaker eye. The weaker eye physically appears more inward or outward than the other eye. Vision may be poor and depth perception may be hindered.(7)

Amblyopia is usually 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- early childhood- so that there is no permanent damage to the eyes.  A common treatment is to place an eye patch over the better eye to help the weaker eye get 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, causing misalignment.  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 getting the eye muscles stronger. Eye muscle exercises are often prescribed, and 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 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. Uncontrolled eye movement can be the result of any damage to these parts of the brain. Nystagmus may be congenital or obtained later 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 forms of conjunctivitis.  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 is a priority to avoid close contact with others while experiencing 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 gradually impaired. A cataract causes no pain to the eye, but symptoms include blurred vision, increased sensitivity to light, halos around lights, and the fading of bright colors. Someone with a growing cataract may go through several changes of eyeglass/contact prescription.(14)

Cataracts are a common eye ailment. About half of all Americans develop some sort of cataract by age 65, including ones that don’t cause vision impairment. 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, treating a cataract usually requires surgery to replace the clouded lens with a lens implant. The surgery is typically short and the recovery process is minimal.(16)

Corrective Lenses and How They Function

The eye is a specialized structure through which the brain can take in and analyze rays of light. Light strikes the eye on the cornea and travels through it to 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 shaped in a way that does not allow light to correctly hit the retina, one will experience blurry vision. Refractive error is the technical term for imprecise vision. (17)

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

Footnotes

Eye Health For Teachers

• Table of Contents
• Module 1
• Module 2
• Module 3
• Module 4
• Module 5
• Module 6