What Conditions can Vision Therapy Treat?
Vision Therapy is a behavioral approach to correcting various eye problems that affect one's ability to receive and process visual information. A person may have "perfect" vision while reading an eye chart, pass a vision screening by reading 20/20, and still have developmental vision problems. The areas most often affected are focusing, eye teaming, eye movements and visual processing.
Vision Therapy is an individualized treatment program designed to improve and sometimes eliminate conditions such as lazy eye (amblyopia), crossed eyes (strabismus), focusing insufficiency and excess, ocular muscle dysfunction, and learning-related vision disorders. Specialized lenses, filters, prisms and instruments are used in a training program, which is customized for each patient. Vision Therapy is a sub-specialty of Optometry and only 5-10% of optometrists provide Vision Therapy.
Amblyopia is an eye problem that causes poor vision and is most often diagnosed in children. The problem occurs when the connections between the eye and the brain do not develop properly. These connections are like roads - they carry vision information from the eyes to the parts of the brain that enable us to see. If these roads between the eyes and the brain do not get made, amblyopia occurs. These connections are made when children are young. Amblyopia is also called "lazy eye" in layman's terms. There are several causes of amblyopia which cannot be detected without a comprehensive eye exam.
Strabismic amblyopia occurs when strabismus (eye turn) is present and the eyes are not working together. If the brain paid attention to both eyes in someone who had strabismus, the person would see everything double. Both eyes need to work together and point straight ahead in order for the brain (and person) to see things normally. In order not to see double, the brain favors the eye that doesn't turn. Since the brain isn't paying attention to the eye that turns, the connections to the brain from that eye do not develop properly.
Refractive amblyopia refers to the condition when the eyes have an unequal "refractive power" or glasses prescription. One eye may be nearsighted and the other may be farsighted, or the amount of nearsightedness or farsightedness in each eye may be very different. Because the brain cannot "balance" this difference in prescription between the eyes, it picks the eye that is "easier" to see with and develops a preference to use this eye only. The same problem then occurs as with strabismic amblyopia: the proper connections between the "bad" eye and the brain do not get made.
Other causes of amblyopia include: congenital cataracts, eye tumors, ptosis (drooping eyelid) and eye trauma.
Strabismus, more commonly known as crossed-eyes, is a vision condition in which a person cannot align both eyes simultaneously under normal conditions. One or both of the eyes may turn in, out, up or down. An eye turn may be constant (when the eye turns all of the time) or intermittent (turning only some of the time, such as, under stressful situations or when ill). Whether constant or intermittent, strabismus always requires appropriate evaluation and treatment.
Types of Strabismus:
- Esotropia (eye turns in)
- Exotropia (eye turns out)
- Hypertropia (eye turns up)
What is a Focusing Problem?
Vision is a dynamic function and in order to see properly we have to change the focus of our eyes every time we look from one object to another. Most people are not even aware that we have to focus our eyes. This is because in most people the focusing system of the eye operates so well that objects always appear in focus.
In reality, a focusing adjustment is made every time we look from one place to another. This adjustment is made with the help of a muscle in the eye called the ciliary muscle or the focusing muscle. When a child looks from the board to his desk, for instance, he must constrict or contract this muscle, which changes the shape of the lens in the eye and allows the child to see the print in his book clearly. When the child wants to look back to the board he must now relax the focusing muscle, which permits clear vision at a distance.
A focusing problem occurs when the child is unable to quickly and accurately constrict or relax the focusing muscle, or if the child is unable to maintain this muscle contraction for adequate periods of time.
What is an Eye-teaming Problem?
We have two eyes and in order to see properly we have to use our two eyes together in a very precise and coordinated fashion.
Every time we look at something we must accurately aim the two eyes directly at the object of concern. Each eye sends an image to the part of the brain that is involved in the process of seeing. This part of the brain, called the visual cortex, then tries to combine these two images to make one "fused" image. If these images are identical the result is normal, clear, single vision and a perception of depth. If, however, the two eyes are not performing in a coordinated manner, the visual cortex will receive two different images. This can result in double vision and/or visual discomfort.
As you can imagine double vision and discomfort are not easy for a child or an adult to tolerate. It becomes very difficult to function either at school, play, or work if double vision or visual discomfort occurs. Eye-teaming problems, which result in such symptoms, actually have more impact on learning or performance at work than do vision problems, which cause a lack of clarity.
There are two types of eye-teaming problems:
- Convergence problems (bringing the two eyes in together)
- Divergence problems (releasing the eyes from a convergence position)
Eye Movement Dysfunction
What is Oculomotor Dysfunction?
Oculomotor Dysfunction is a fairly common eye problem in which people are unable to follow a moving object accurately (pursuit fixation) or unable to quickly shift their eyes from one point of fixation to another (saccadic fixation is necessary for tracking skills while reading or copying). These skills are necessary for optimal academic and athletic performance. Oculomotor Dysfunction develops over a period of time but can be treated by following a course of corrective eye exercises.
What is a Tracking Problem?
In order to process visual information properly the eyes must move smoothly and quickly from word to word or from one object to another target. Every time a child looks from the board to the book, for instance, the eyes must accurately jump from one target to another. The same is true for reading. If a person has problems with tracking, they have a saccadic deficiency.
What Causes Oculomotor Dysfunction?
There are six muscles around each eye. These six muscles work together in an extremely sophisticated manner in order to accurately control eye movements. Oculomotor Dysfunction occurs when these muscles are not properly coordinated. The causes of Oculomotor Dysfunction are many, ranging from slow development to disease of the central nervous system. An eye exam is needed to diagnose the condition.
Visual Perception Dysfunction
What is a Visual Processing Problem?
The ability to analyze and interpret visual input is sometimes referred to as visual processing or visual perceptual skills. Just because a child can see clearly and comfortably does not guarantee that the brain will be able to make use of the incoming information.
These skills are important when a child is young and is learning letter and number recognition, reading and early math skills. We believe that visual processing skills develop in most children without the need for any special attention or intervention. However, in some children the development of visual processing skills does not keep pace with the child's growth in other areas. This type of lag can lead to difficulty in the early grades in school.
What types of Visual Processing problems can occur?
When a child has developmental lags in the area of visual processing it can result in variety of problems including:
- Deficiencies in the area of visual motor integration skills may make handwriting more difficult resulting in poor spacing, inability to stay on the line, and excessive erasures. The child's ability to complete written work within an allotted period of time may also be affected.
- Dysfunctions in visual memory may cause prolonged time copying assignments, difficulty recognizing the same word on the next page, and difficulty retaining what is seen or read.
- Confusion in the area of directionality may result in reversals of forms, letters such as "b" and "d" and words such as "on" and "no" and "was" and "saw".
- Directionality also allows a person to differentiate between left and right. Laterality is the ability to differentiate between another person's left and right.
- Visual form perception and discrimination problems may result in his confusing similar beginnings, endings, and even entire words.