Vision development is a LEARNED PROCESS that begins in utero, and plays a leading role in the development, growth and daily performance of people. The actions of the visual system involve approximately 70% of the pathways of the brain. Vision is our DOMINANT sense and it is estimated that 80% of our learning happens through our visual system. Processing visual
information and tasks requires involvement of every part
of the brain.
We do not typically observe signs to measure progress
of vision development, but rather evidence of problems
that have occurred. 20/20 vision does not necessarily
mean a person has ‘perfect vision.’ Visual acuity, reading
the eye chart, is a measure of eyesight and only one
component of ‘good vision.' Other components of good
vision include healthy eyes, visual integration with the other
systems/senses of the body, and visual skills such as eye teaming,
eye focusing, and eye tracking. At MVP, we evaluate these vision components, the first step in helping people in all stages of life reach their optimal vision potential.
When most of us think of “perfect” vision, we think of 20/20.
Over 100 years ago, Dr. Snellen determined the smallest target size a human eye could see. This target size came to be labeled (in the United States) as a size 20 letter at a distance of 20 feet from the eye. Thus, 20/20 means you can see a size 20 letter from 20 feet away. So, a person with 20/40 vision can see at 20 feet what a 20/20 person could see at 40 feet. Sound confusing? It is!!!!
If prescription lenses are required, the lenses will
often provide optical correction for:
20/20 IS JUST A MEASURE
OF VISUAL ACUITY (CLARITY)
AT A 20 FOOT DISTANCE!
At MVP, a FULL Functional or Neuro-Optometric
evaluation measures binocular (both eyes working together) function, in addition to the standard eye refraction to 20/20 and eye health. Visual motor guidance, ocular motility (eye tracking), accommodation (eye focusing), vergence (eye alignment), and visual information processing/visual perception abilities are documented. From these medical findings, treatment options are discussed with each patient and/or family members.
Amblyopia (often referred to as “lazy eye”), is a condition where one eye does not see nearly as well as the other. This condition is not correctable by glasses or contact lenses. The brain actively suppresses the images seen by the amblyopic eye, not allowing 20/20 vision to develop between the eye and the brain. The favored eye compensates for the amblyopic eye so the child/adult may not be aware of the problem. This may lead to other dysfunctions such as poor depth perception (3D).
Causes of Amblyopia
Anything that interferes with clear vision in either eye during infancy
and childhood can cause amblyopia by affecting the development of the visual system.
Here are reasons why amblyopia can develop:
Misaligned eyes or constant strabismus (eye turn)
Significant differences between the clearness of
the images seen by each eye due to farsightedness, nearsightedness, or astigmatism
An obstruction of vision within one eye due to
injury or disease
Treatment of Amblyopia
Early treatment is usually simple, often employing glasses, occlusion therapy and rehabilitation exercises. Dr. Ashley may start by prescribing a short term patching regimen to improve the clarity of vision in the amblyopic eye, and then refer for rehabilitation to teach the eyes how to work together. While detection and correction before the age of two is considered to offer the best outcome, recent scientific research has dis-proven the long held belief that children over seven years old can not be successfully treated.
Strabismus 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 “cross eyed” (esotropia), out “wall eyed” (exotropia), up (hypertropia), or down (hypotropia).
IT IS ESTIMATED
THAT UP TO
5% of all children
HAVE SOME DEGREE
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 conditions or when ill).
The causes most often develop in infants and young children, although it can occur in adults.
Treatment for Strabismus
In most cases the problem does not improve on its own as the child grows.
Treatment varies depending on the cause
of the eye turn and may include:
Vision rehabilitation (non-surgical approach)
Eye muscle surgery
What is it?
Autism is a neuro-biological disorder. People with autism have difficulty processing and responding to information from their senses. They also have difficulties with communication and social interaction. Symptoms of autism can include lack of reciprocal social interaction, delays in development, and inappropriate response to sensory information.
People on the Autism Spectrum can have minimal
to significant challenges in one or more of the core
binocular (two eyes) visual areas:
VISUAL MOTOR GUIDANCE– visually-directed gross
(big muscle, such as throwing a ball) and fine motor
(small muscle, such as writing) skills.
OCULAR MOTILITY (eye tracking) – the ability to
follow with the eyes (minimal head or body movement)
a moving object in visual space, or the ability to
follow letters in a word or words on a line of print.
ACCOMMODATION (eye focusing) – the ability to
see near-centered objects, including words on
paper or in a book, with normal acuity (clarity).
Eye focusing difficulties will cause near-centered
targets to appear blurry.
VERGENCE (eye coordination & eye alignment) –
the ability to have both eyes aligned (aimed) at the
same point in visual space. Eye coordination and
eye alignment difficulties will cause diplopia
(double vision), or suppression (turning off) of
the vision in one eye to prevent double vision.
VISION INFORMATION PROCESSING & VISUAL
PERCEPTION– the ability to understand, get meaning,
recall and remember visual data.
Vision Problems & Autism
Visual problems are very common in individuals with autism. Visual symptoms of autism can include lack of eye contact, staring at spinning objects or light, fleeting peripheral glances, side viewing, and difficulty attending visually.
People with Autism often use visual information inefficiently. They have problems coordinating their central and peripheral vision. For example, when asked to follow an object with their eyes, they usually do not look directly at the object. Instead, they will scan or look off to the side of the object. They might also have difficulty maintaining visual attention. Eye movement disorders and crossed eyes are common in the autistic spectrum.
Poor Integration of Central & Peripheral Vision
People with ASD can also ignore peripheral vision and remain fixated on a central point of focus for excessive periods of time. Poor integration of central and peripheral vision can lead to difficulties in processing and integrating visual information. Motor, cognitive, speech, and perceptual abilities can also be affected when visual processing is interrupted.
Hypersensitive Touch & Vision
Many people with autism are tactually or visually defensive. Tactually defensive people are easily over-stimulated by input through touch. They avoid contact with specific textures. Visually defensive people avoid contact with specific visual input and might have hypersensitive vision. They have difficulty with visually “holding still” and frequently rely on a constant scanning of visual information in an attempt to gain meaning.
Treatment of Visual Problems Associated with Autism
Depending on the results of testing, lenses to compensate for nearsightedness, farsightedness, and astigmatism (with or without prism) may be prescribed. Vision rehabilitation activities can be used to stimulate general visual arousal, eye movements, and the central visual system. The goals of treatment may be to help the patient organize visual space and gain peripheral stability to better attend to and appreciate central vision and gain more efficient eye coordination and visual information processing.
ADD & ADHD
Some children with learning difficulties exhibit specific behaviors of impulsivity, hyperactivity, and distractibility. A common term used to describe children who exhibit such behaviors is Attention Deficit Hyperactivity Disorder (ADHD). Undetected and untreated vision problems can elicit some of the very same signs and symptoms that are commonly attributed to ADHD. Due to these similarities, some children with vision problems are mislabeled as having ADHD.
New Research in Vision & ADD/ADHD
A recent study by researchers at the Children’s Eye Center, University of San Diego, uncovered a relationship between a common vision disorder, convergence insufficiency, and ADHD. The study “showed that children with convergence insufficiency are three times as likely to be diagnosed with ADHD than children without the disorder.”
Dr. Granet of the Children’s Eye Center commented,
We don’t know if convergence insufficiency makes ADHD worse
or if convergence insufficiency is misdiagnosed as ADHD. What
we do know is that more research must be done on this subject
and that patients diagnosed with ADHD should also be evaluated
for convergence insufficiency and treated accordingly.
Much of our academic and work environment requires students to sustain visual attention on near-point tasks for lengthy periods. In order to accomplish this, the two eyes must coordinate as a team and point at the same place. The two eyes must focus at the proper distance and maintain clarity. The two eyes must move and track to understand or get meaning from what is viewed.
These functional aspects of vision go far beyond whether a person can see 20/20 or not. When these functional visual skills are lacking, the student is unable to sustain attention on near-point tasks. Fatigue and distraction set in and the student begins to make careless mistakes, fidgets & squirms, talks excessively, interrupts others, fails to follow directions, or begins to move about to touch and feel objects in the environment.
A developmental optometry evaluation will reveal whether visual factors are contributing to a student’s attention difficulties.
Persons with diagnoses including Down
syndrome, developmental delay, cerebral palsy, and intellectual challenges
can experience life-impacting visual symptoms.
These symptoms may include difficulty making eye contact, rubbing
eyes, holding near vision material either very close or very far away
from eyes, squinting eyes, headaches from visually-directed activities, frustration following a moving target, challenges catching a ball, and
overall visual avoidance.