Vision Therapy: Glossary of Terms

Published August 30, 2020

AMBLYOPIA also known as “lazy eye” is a visual condition that affects approximately 2 or 3 out of every 100 children in the United States.

Amblyopia causes reduced visual acuity or visual skills in one eye which can not be corrected by eyeglasses or contact lenses. This condition typically causes a loss of stereoscopic vision (3D) and depth perception. Research has shown that patients with amblyopia are more likely to sustain injuries due to the loss of their good eye, when compared to individuals with two good eyes.

With early detection and treatment through vision therapy, patients with amblyopia can recover clear and comfortable binocular vision.

For many years, it was thought that amblyopia was only amenable to treatment up to the age of seven or eight years. However, scientific research by the National Eye Institute, National Institutes of Health, Department of Health and Human Services has now proven that effective treatment can take place up to the age of 17.

Behavioral/developmental optometrists report decades of successful treatment results with adult amblyopia patients. However, early detection and treatment are still preferred, as the length of the treatment period increases dramatically the longer the condition has existed.

For more information, see Vision Therapy for Lazy Eye.

People often confuse amblyopia (lazy eye) with strabismus (crossed eyes, eyes that wander, turn or deviate). These are two different vision conditions, though they are sometimes interrelated.

See Strabismus below or see What Is Strabismus (Crossed-Eyes)?

ATTENTION DEFICIT HYPERACTIVITY DISORDER (ADHD): Formerly called ADD. A condition that is generally known for causing inattentiveness, impulsivity, and/or hyperactivity.

Children with ADHD may be hyperactive and unable to control their impulses. Or they may have trouble paying attention. These behaviors interfere with school and home life.

Adults with ADHD may have trouble managing time, being organized, setting goals, and holding down a job. They may also have problems with relationships, self-esteem, and addiction.

ADHD symptoms can mimic the symptoms caused by a vision condition called convergence insufficiency. As a result, many children are misdiagnosed with ADHD, causing unnecessary negative stigmas and low self esteem.

For more information, see Vision Therapy for ADHD.

BEHAVIORAL OPTOMETRIST: See Developmental Optometrist below.

BINOCULAR VISION: Vision as a result of both eyes working as a team; when both eyes work together smoothly, accurately, equally and simultaneously.

BINOCULAR DEPTH PERCEPTION: A result of successful eye teaming and stereoscopic vision; the ability to visually perceive three dimensional space; the ability to visually judge relative distances between objects; a visual-motor skill that aids in accurate movement in three-dimensional space.

BINOCULAR VISION IMPAIRMENT: A visual condition in which the two eyes fail to work together as a coordinated team, resulting in a partial or total loss of binocular depth perception and stereoscopic vision.

At least 12 percent of the population has some type of binocular vision impairment. Amblyopia and strabismus are the most common types of binocular vision impairment.

CONVERGENCE INSUFFICIENCY: A common near vision problem that interferes with a child’s ability to see, read, learn, and work at near distances; an eye teaming problem in which the eyes have a strong tendency to drift outward or away from the target when reading or performing near vision activities.

When the eyes drift, it can cause fatigue, eye strain or double vision. The condition can manifest or worsen in the later school years, as near work, homework, and reading demands significantly increase.

Convergence insufficiency often goes undetected and untreated in children because testing for this condition is typically not included in a pediatrician’s vision test, or a school vision screening.

A child can pass the 20/20 vision test and still have convergence insufficiency.

According to the National Eye Institute and Mayo Clinic, in-office vision therapy is the best treatment for convergence insufficiency in children.

For more information, see Convergence Insufficiency.

DEVELOPMENTAL OPTOMETRIST: (Behavioral Optometrist or Pediatric Optometrist) A doctor of optometry who specializes in the practice of in-office vision therapy.

The term ‘behavioral’ came into use because these optometrists will consider how environmental, nutritional and/or behavioral factors affect visual health and function. The practice focus of behavioral optometrists has no relation to the term Behaviorism (B. F. Skinner).

DIGITAL EYE STRAIN (DES): Also called Computer Vision Syndrome (CVS). A condition that results from prolonged usage of digital devices. Digital eye strain can cause sore or tired eyes, blurry vision, dry eyes, headaches, and even neck or shoulder pain.  The condition is best treated with vision therapy and specific behavioral changes.

For more information, see Digital Eye Strain.

DIPLOPIA OR DOUBLE VISION:  A condition in which a single image appears double.

For more information, see Double Vision (Diplopia).

DRY EYES: A common condition that results from insufficient tear quantity, or inadequate tear quality.

Dry eyes can range from a mild inconvenience to a chronic problem, and cause many uncomfortable symptoms that can impact performance of daily activities. There are many different treatments for dry eyes, depending on the severity of the condition.

For more information, see Dry Eyes.

DYSLEXIA: Margaret S. Livingstone, Ph.D., Professor of Neurobiology, Dpt. of Neurobiology, Harvard Medical School defines dyslexia as follows: “Developmental dyslexia is the selective impairment of reading skills despite normal intelligence, sensory acuity, and instruction.

Normal vision and hearing are essential parts of normal sensory acuity, so it is critical to rule out any problems with vision or hearing when considering the diagnosis and/or treatment of dyslexia.

A 20/20 vision test only evaluates visual acuity at a distance of 20 feet. A person can pass this vision test and still have serious vision problems. Similarly, the standard hearing test only looks for hearing loss, but does not test for other auditory processing abnormalities.

Dr. Livingstone’s research on developmental dyslexia also showed that, “Visual abnormalities were reported to be found in more than 75% of the reading-disabled children tested.” This statement was made about reading-disabled children, not dyslexic children— emphasizing that testing for dyslexia must include a multi-disciplinary approach, and a thorough evaluation of the child’s sensory function and integration.

For more information, see Optometric Management of Dyslexia.

EYE CONDITIONS: Conditions that affect the eyes and cause a range of symptoms, from a minor inconvenience to permanent blindness.

The most common eye conditions include: Cataracts, Glaucoma, Diabetic Retinopathy, Macular Degeneration, Corneal Diseases, Ocular Oncology, Pterygium and Pinguecula.

For more information, see Eye Conditions.

HYPEROPIA: Also known as long-sightedness, or far-sightedness. This condition causes near objects or images to appear blurry or out of focus. For more information, see What Is Long-Sightedness?

LAZY EYE: See Amblyopia above.

MYOPIA: Also known as nearsightedness or short-sightedness. This condition causes distant objects to appear blurry or out of focus.

For more information, see What Is Myopia?.

NEURO-OPTOMETRY: A branch of optometry specializing in vision problems related to neurological trauma, disease, and metabolic or congenital conditions. When the visual system is affected neurologically, it can impact performance of daily activities.

For more information, see Neuro-Optometry.

OPHTHALMOLOGIST OR PEDIATRIC OPHTHALMOLOGIST: A doctor of medicine (M.D.) specializing in surgery and diseases of the eye. To learn more about the differences between the practices of ophthalmologists and optometrists.

For more information, see Should I See an Optometrist or Ophthalmologist?

ORTHOPTIC THERAPY: A limited form of vision therapy which trains convergence, binocular vision and eye teaming skills. This is a non-surgical or post-surgical treatment, and is typically home-based.

Mayo Clinic and the National Eye Institute have proven that in-office vision therapy is more effective in the treatment of a convergence disorder, due to the fact that orthoptics does not address sensory integration or visual processing issues.

Orthoptics first became popular in Europe in the 1900s. David Wells, M.D., an ophthalmologist at Boston University, is credited with introducing orthoptics to the U.S. in 1912. Currently, orthoptics is practiced by very few ophthalmologists and/or orthoptists in the United States, as ophthalmologists are eye surgeons and rarely offer this non-surgical treatment.

SPECIAL NEEDS: Specialized services required due to a learning difficulty, physical disability, or emotional and behavioral difficulties.

Research shows that a higher percentage of children with special needs may have vision problems that are undiagnosed because their associative behaviors are perceived as part of their special needs diagnosis.

For more information, see Vision and Special Needs.

STEREOPSIS: Stereoscopic vision is a byproduct of good binocular vision, where the vision of separate images from two eyes are successfully combined into one three-dimensional image in the brain.

STRABISMUS: Also known as “crossed eye”, “wall eye”, or “wandering eye”. Strabismus comes in various forms known as esotropia, exotropia, and hypertropia.

Strabismus affects approximately 4 out of every 100 children in the United States. It is a visual condition in which the two eyes point in different directions. One eye may turn either in, out, up, or down while the other eye aims straight ahead.

Due to this condition, both eyes do not always aim simultaneously at the same object, resulting in a partial or total loss of stereo vision and binocular depth perception. The eye turns may be visible at all times or may only occur on occasion. In some cases, the eye turn goes unnoticed to the untrained observer.

A consultation with an optometrist who offers supervised in-office vision therapy is recommended with this binocular vision condition.

For more information, see What Is Strabismus (Crossed-Eyes)?

VISION: The act of perceiving visual information with the eyes, mind, and body. Vision is recorded as visual acuity from 20 feet away, such as 20/20, 20/30 or 20/40 etc.

For more information, see What Is a Visual Acuity Test?

VISION SKILLS: The skills the brain uses to make sense of the visual information it receives. There are 17 visual skills that we use on a daily basis, without even realizing it. These skills are necessary for optimal functioning and successful performance at school, work, and on the sports field.

For more information, see The 17 Key Visual Skills.

VISION THERAPY: Also known as vision training, visual therapy, visual training. A supervised therapy involving eye exercises aimed at improving the visual skills, such as eye teaming, binocular coordination and depth perception, focusing, visual acuity, visual processing and “hand-eye” or “vision-body” coordination.

Vision therapy can involve a variety of procedures and exercises to correct neurophysiological or neurosensory visual dysfunctions.

Some vendors of self-help eye exercise kits have taken to advertising under the term “Vision Therapy.” This is misleading. Vision Therapy is practiced by optometrists and includes evaluation, supervision, and the use of medically regulated devices.

For more information, see What Is Vision Therapy?