Relevant Terminology

The following are common terms heard at the eye doctor’s office or encountered when researching eye and vision care. 

Dilation, or widening of the pupil, takes place during a comprehensive eye exam.  It enables an eye doctor to see more of the retina, the light-sensitive layer of tissue at the back of the eye, to check for signs of disease.

The Snellen Eye Chart is the standard used in measuring the eye's ability to distinguish detail and shapes (visual acuity). The chart is based on the work of a Dutch ophthalmologist, Dr. Hermann Snellen, who in 1862 designed this system for describing human vision.  Made up of a series of letters, numbers or symbols of progressively smaller size, the largest at the top, a person who can clearly read a one-inch letter at a distance of 20 feet is considered to have normal “20/20” vision. All measurements obtained from use of the Snellen Chart are a comparison to that standard. Persons who have 20/40 vision, for example, can read at 20 feet what people with normal vision can read at 40 feet.  The patient is allowed to keep on eyeglasses or contact lenses and is positioned 20 feet in front of the Snellen Eye Chart. Covering one eye at a time, the patient is asked to read progressively smaller letters until it is no longer possible to read the small letters. Then the test is repeated with the other eye.  Measuring only visual acuity, the Snellen Eye Chart does not prove the absence of an eye disease or any other eye problem.\

A Comprehensive Vision Examination includes tests to myopia, hyperopia, astigmatism, eye coordination and eye muscle function, eye focusing abilities and overall eye health, which in most  cases includes dilation.  A child should have a thorough eye exam by age 3 to make sure his or her vision is developing properly and there is no evidence of eye disease. An eye doctor can prescribe treatment if necessary to correct a vision development problem.  With today's diagnostic equipment and tests, a child does not have to know the alphabet or how to read to have his or her eyes examined. Here are several tips, suggested by the American Optometric Association to make your child's eye exam a positive experience:

1. Make an appointment early in the day. Allow about one hour.
2. Talk about the examination in advance and encourage your child's questions.
3. Explain the examination in terms your child can understand, comparing the E chart to a puzzle and the instruments to tiny flashlights and a kaleidoscope.

Unless the eye doctor advises otherwise, the next eye exam should be at age 5. By comparing test results of the two examinations, an eye doctor can tell how well a child's vision is developing for the next major step into school.

Vision Screenings are a precursory process usually conducted in schools or by a pediatrician. While unable to diagnose an eye or vision problem, a screening may indicate the potential need for further evaluation.  Vision screenings may not recognize as many as 60% of children with vision problems, further emphasizing that by the age of 3, every child should have a comprehensive eye exam with an eye doctor.

Vision Therapy is the programmed series of visual activities, which may include the use of selected lenses and prisms, applied in an effort to explore, extend, and enhance all the visual abilities of which a person is capable. These procedures are practiced mostly by developmental eye doctors, and have been generated and validated by these professionals through clinical practice and carefully designed research. Such regimens have been beneficial to students whose academic problems have some basis in visual insufficiencies. In addition, such vision care has been beneficial in dealing with visual difficulties brought on by excessive stress in the classroom.