Vision Information for the Family - Vision terminology
Accommodation is the ability to change the focus of the eyes as the distance to an object changes. An example of when this ability is needed is when a child looks from book to chalkboard and back again.
Amblyopia (lazy eye)
Usually occurring before age six, amblyopia is the loss of vision or lack of development in one eye unrelated to any health problem. Amblyopia usually results when both eyes are not used together.
Because the images sent to the brain from each eye differ, the brain eventually learns to ignore the image sent by one eye and sees only with the good eye. Early detection and treatment is important to avoid permanent loss of eyesight. Treatment can involve using corrective lenses, prisms and patching the good eye. In most cases, a combination of treatment techniques will need to be used.
With astigmatism, the front surface of the eye, the cornea, is irregularly shaped, and light is not focused correctly on the retina. This causes eyesight to be blurred at all distances. Astigmatism can generally be treated with prescription eyeglasses or contact lenses.
Cataracts occur when the clear lens of the eye becomes clouded, resulting in blurred or hazy eyesight. Although cataracts are most common in adults over age 55, they can be found in people of any age, including newborns, in fact, statistics show that one in 10,000 children are afflicted with congenital cataracts. Treatment usually involves surgical removal of the cataract and replacement with an intraocular lens implant. Left untreated, cataracts can result in blindness.
Coordinated field of movement
With a coordinated field of movement, the eyes work together and move in the same direction. If the eyes are not aligned properly and send different images to the brain, the brain will have to ignore one of the images.
This is the ability to aim the eye and hold that aim on an object, such as a word in a line of print.
Glaucoma is the painless internal eye pressure caused by an excess fluid buildup in the eye. Symptomless in its early stages, glaucoma can damage the optic nerve and result in severe vision loss or blindness. Glaucoma can usually be treated with eye drops or medicine. In some cases, surgery is needed to reduce pressure in the eye.
Individuals who are farsighted see distant objects more clearly than those up close. In mild cases of hyperopia, no treatment is needed. In more severe cases, eyeglasses or contact lenses may be recommended.
As the leading cause of vision loss for people over 50, macular degeneration results from changes to the macula, which is responsible for clear, sharp vision.
According to the American Optometric Association, some common symptoms of macular degeneration include:
- A gradual loss of ability to see objects clearly.
- Objects appear to be distorted in shape or straight lines appear wavy or crooked.
- A gradual loss of clear color vision
- A dark or empty area appearing in the center of vision.
Although vision lost to macular degeneration cannot be restored, early detection and intervention can help limit the damage caused by this condition. Ask your doctor of optometry for more information.
Myopia is a vision condition in which you see close objects more clearly than those farther away. Nearly 30 percent of the U.S. population has myopia, which usually occurs before the individual reaches age 20. Eyeglasses and contact lenses can be used to correct nearsightedness.
This year, more than nine million Americans will have to start holding their newspapers a little farther from their face in order to see them clearly.
Although treatable, this age-related vision condition, known as presbyopia, is irreversible. It is caused by a loss of flexibility of the crystalline lens of the eye.
To compensate for the reduced ability to focus on close objects, reading glasses, bifocals, trifocals, and progressive lenses can be prescribed. There are also several contact lens options available to treat presbyopia.
Ask your doctor of optometry for information about the best treatment option for your lifestyle.
Saccades are the abrupt voluntary shift in fixation from one point to another. When children are reading, this occurs as their eyes jump from word to word or from the end of one line to the beginning of another.
Strabismus (Turned eye)
This is a condition in which the eyes are not properly aligned with each other and different images are sent to the brain. One or both eyes may turn in, out, up or down. It is estimated that five percent of children have strabismus, and if the condition goes undetected and remains untreated, permanent loss of vision can result. If detected at a young age, treatment can include eyeglasses, prisms, surgery or therapy.
This involves the ability of the eyes to rotate toward or away from each other to remain focused on an object as it approaches or moves away.
The ability to follow a slow moving target. Also called tracking.
What does 20/20 mean?
Most people use this to describe perfect eyesight. Actually, it means that you can see clearly at 20 feet what should normally be seen at that distance. By contrast, if you have 20/100 vision, you must be 20 feet away to see what a person with 20/20 vision can see at 100 feet.