Amblyopia: Also Referred to as “Lazy Eye”

Amblyopia describes reduced visual function in an otherwise healthy eye. Most of the early research on neuroplasticity in the brain has been done with amblyopia. Vision will not develop properly when an eye is not given appropriate developmental experiences. This occurs when an eye is turned and is ignored by the brain to avoid double vision and confusion. It also occurs when the image from an eye is consistently out of focus as happens when one eye is much more farsighted than the other or both eyes have high degrees of astigmatism.

Amblyopia is described by the best visual acuity obtainable with glasses, but the visual detriment involves much more than acuity. An eye with amblyopia does not track as well, it processes information more slowly, it perceives objects as running together, and does not see sequences in the correct order. It is the most common cause of blindness in children and young adults. Recent research has changed the treatment of amblyopia with higher rates of success. A child with amblyopia rarely realizes that they have a problem. It is what they are used to.

Convergence Insufficiency

Convergence insufficiency is the most common of the disorders in which the eyes do not team and focus together automatically. These problems are common in children and adults. They are assessed through a combination of signs, symptoms, and testing. (See the Convergence Insufficiency Symptom Survey.) These conditions often go unrecognized because the signs and symptoms have a variety of possible causes and are usually not assessed in routine eye examinations. Adults may just accept their discomfort and difficulties as normal; something else we have to live with. In children these visual problems are often mis-attributed to attention deficit disorder, learning disabilities, or laziness.

The demands for hours of concentrated visual activities within arm’s reach continues to increase. Young children are expected to read one year earlier than their parents were expected to read. Print size gets small and pages get crowded before many children have the visual skills to handle this visual and cognitive load. Children are also involved with staring at illuminated screens for hours a day starting at a young age. This causes eyestrain for many of them (but they may persist due to their engagement in what they are doing). It also reduces the type of play that children did a generation or two ago which are instrumental in the development of visual (and other) skills.

Most adults spend time looking at illuminated screens. (See computer use and eyestrain). This is one of many examples of what we do in the 21st century which is a challenge to how we have adapted through evolution. Our vision adapted to help us to survive and navigate, not to stare at small print. Across the developed world, more people are becoming increasingly nearsighted. Researchers have not determined all of the contributing factors, but changes in our lifestyle are a factor.

Convergence insufficiency and related problems can be treated with glasses, vision therapy, or a combination of treatments. Treatment is effective in children and adults. Modifications in what people do and how they do it are frequently part of the treatment. Inadequate rest is common in all age groups and makes these problems worse. These problems are common in people who have had a head injury and now have post-concussion syndrome.

Learning Related Vision Problems

Learning related vision problems often exist in combination with other problems. Most learning problems in school are related to reading. Visual skills play a critical role in learning to read and in reading for information.

Visual attention to detail is important in learning to read as are figure-ground skills which enable the discrimination of graphemes within words. Visual memory is critical as is the integration of vision with audition and language skills.

Visualization is essential for spelling. It is also necessary to picture what we read to aid in comprehension and to relate what we read to what we have learned previously.

Efficient reading is dependent on ocular motor skills and the speed of visual processing. Our eyes jump four times a second as we are reading despite our perception that they move smoothly across the page. They must be precisely aligned one-third of the way into a word to optimize input. We must be able to isolate words within a crowded array and, at the same time, see where to move our eyes next. This is a learned skill which takes place subconsciously while we are consciously attending to what we are reading.

Decoding while reading is not only an interruption, but it also places a heavy burden on focusing and eye teaming as we stop and stare. Eyes get tired much more quickly when we are staring than when they are moving to read. Decoding while reading also prevents practicing the eye movements necessary for fluent reading.

The visual demands of writing are frequently overlooked. Children draw letters, staring to guide their pencil, for years before writing is embedded in motor memory and becomes automatic. As adults, our vision monitors what we are writing. It does not guide our pen. Writing often causes more eyestrain than reading for children. Like reading, writing places a high demand on working memory; forming letters, spelling words, spacing, capitalization, punctuation, while at the same time trying to write a meaningful sentence. Reversible letters such as “b” and “d” serve as a complication for emerging readers. There is more information on vision and reading and writing on our blog.

Post-Concussion Syndrome

People who have had a head injury may experience visual problems as part of their post-concussion syndrome. These include sensitivity to light, difficulty focusing, motion sickness, headaches due to eyestrain, inability to read, and being visually overwhelmed by busy environments such as stores.

The initial treatment for head injuries, after imaging studies, is rest. The brain has an amazing ability to heal itself with rest, but rest for the brain is relative and not always easy for the individual to accomplish. Everything that we do, including sitting, thinking, and worrying, adds to brain activity. After a brain has been injured, it is extremely vulnerable to being overloaded. The symptoms caused by overload and the time it takes to recover are exaggerated when the brain has been injured. Prior to a head injury, pushing through discomfort may be a reasonable choice, but this is no longer an effective strategy. Since it does not take much to become overloaded, the person and family are often blindsided when it happens.

Controlling the amount of light, contrast, and glare are important to avoid over-stimulation. This is managed by modifying the environment, using various densities and colors of tinted lenses, and sometimes through partially covering one or both eyeglass lenses to reduce stimulation.

A combination of modifications to the environment, careful selection of activities, limiting the duration of activities, and prescribing lenses, tints, and vision therapy are the tools to rehabilitate the visual system. It is often impossible to predict the degree and rate of recovery after head injuries. This is disappointing, but accepting that recovery will be step-by-step and focusing on the recovery is very important. The stress of continuously being frustrated at the rate of rehabilitation is an overload which can stall recovery.

Strabismus

Strabismus describes when an individual’s eyes do not align. The misalignment may be constant or intermittent. In most cases, this is not due to a faulty eye muscle, nerve, or mechanical restriction but rather due to poor neuromuscular coordination, this can often be improved through vision therapy. Even when there is a physical reason for the eye turn, vision therapy can often improve cosmetics and function. Children’s eyes tend to wander independently for the first month or so after they are born similar to the random movements of their arms and legs. This should not occur after the first three months. If an eye is misaligned constantly from an early age, the vision in that eye will be ignored by the brain to reduce confusion and the visual function of that eye will not develop properly which is known as amblyopia.