Experts agree that at least 80% of what a sighted person learns is through vision. Schools, television, and movies all use this knowledge effectively to present ideas to their audiences.

Vision is most commonly described in terms of an acuity measure, or the best a person can see. 20/20 is considered normal vision; while 20/50 prohibits driving in Texas without special aids, 20/70 is called a visual handicap, and when a person sees 20/200 or worse in his or her better eye with the best possible correction on that eye, that person is considered to be "legally blind." A person can see with uncorrectable 20/200 vision, but often too little is recognized to be very helpful.

Relative sizes of objects seen with specific acuities are illustrated by these "E's":

Vision Impairments

Vision can be hampered in several ways. Refractive errors can create distortions.

Muscle balance problems, or crossed eyes, can prevent the two eyes from lining up to see the same thing. When they work together to produce one image, this is called binocular vision.

Binocular vision lets us judge the size and distance of an object from simple observation. This is known as depth perception, an important factor for good mobility.

In a young child when there is a great difference between the images "seen" by each eye, binocular vision will not result. An adult may see two images or have double vision, but a child who is learning to use vision will begin to see only the better image. This can develop into a condition known as AMBLYOPIA-where both eyes are healthy, but the brain uses only the information from the good eye and the other becomes "nonfunctional."

Amblyopia diminishes the person's ability to see binocularly, and it virtually reduces the vision to that of the one good eye. As a child grows older with this condition, it becomes extremely difficult to train the poorer eye to "see" within a normal range.

Along with refractive errors and muscle balance problems, injuries and various other physical conditions such as cataracts, glaucoma, and detached retinas can create difficulty in seeing. Symptoms of vision difficulty may include: 

Appearance

• Crossed eyes
• Red eyes
• Watering eyes
• Crusty eyelids
• Frequent styes
• Cloudiness in or around the pupil

 Behavior

• Holds body rigid while looking at distant objects
• Thrusts head forward or backward while looking at distant objects
• Avoids close work
• Has a short attention span
• Turns head to use only one eye
• Tilts head to one side
• Places head close to book or desk when reading or writing
• Blinks excessively
• Rubs eyes often, frowns, or loses place, especially when reading
• Squints
• Closes or covers one eye

Complaints

• Headaches
• Nausea or dizziness
• Burning or itching of eyes
• See blur when looking up from close work
• Sees objects double Undue sensitivity to light

Treatments

• Prescription for glasses or contact lenses
• Surgery for severe muscle imbalance, cataracts, or severe glaucoma
• Medication for infections, allergies, glaucoma, and other conditions
• Educational assistance for the visually impaired and legally blind (this may include visual aids and special classes or schools)

Vision Development Milestones

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Infant Warning Signs of Visual Problems

• Visually unresponsive
• Holds things very close to see them
• Bumps into large objects
• Cannot pick up small objects with accuracy
• Favors one eye when looking at objects
• One or both eyes turn in or out for noticeable periods
• Squints or closes one eye frequently

Department of State Health Services Vision Screening Program

The Department of State Health Services assists in vision screening programs for preschool - school-age children. Workshops are held around the state to train interested individuals to perform basic vision screening.

There is no charge for training. Please contact your regional coordinator for more information.

Who are the Training Screeners and the Specialists?

Department of State Health Services
Vision and Hearing Screening-Mail Code 1938
PO Box 149347 / Austin, TX 78714-9347
1100 West 49th Street / Austin, TX 78756-3199
Phone: 512-776-7420
Toll Free 1-800-252-8023 extension 7420 

Relay Texas: Dial 7-1-1 

Email Vision and Hearing Screening

1. Trained Screeners - In Texas, individuals who screen children for vision problems must be certified through DSHS unless their professional licenses permit such screening.
2. Specialists - People who are educated or trained to perform many specialized services for the visually impaired:
   • Physician - a medical doctor licensed to practice medicine in the United States
   • Ophthalmologist - a medical doctor trained in the diagnosis and treatment of defects and diseases of the eye.
   • Optometrist - a professional trained in vision disorders, evaluation for visual aids, and visual habilitation.
   • Optician - a professional who grinds lenses and fits them into frames to the wearer's needs.
   • Orthoptist - a professional who plans exercise programs for the development or restoration of normal teamwork of the eyes (binocular vision)
   • Visual Handicap Educator - an educator who is trained in techniques designed to increase a visually impaired individual's social adaptation skills, including learning and mobility skills.