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Accommodation (also known as
focusing)
The eye's ability to adjust focus on objects at varying distances.
See Near point of accommodation and accommodative facility. Behavioral
theory suggests that focusing is closely related to the identification
mechanism which ensures that the object under scrutiny is the most
clearly seen ensuring it remains the centre of attention. See near
point of accommodation and accommodative facility. |
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Accommodative Facility
The eyes ability to repeatedly change focus from one distance to an
other. Often measured by use of special flipper lenses. Measurement
of each eye in turn is usually made followed by comparing the performance
to that of both eyes working together. |
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Amblyopia ("lazy eye")
A visual defect that affects approximately 1-2% of the population.
Amblyopia involves lowered visual acuity (clarity) and/or poor muscle
control in one eye. The result is often a loss of stereoscopic vision
and binocular depth perception. Vision therapy can benefit this condition,
but early detection is very important. For many years, it was thought
that amblyopia (lazy eye) was only amenable to treatment during the
"critical period". This is the period up to age seven or
eight years. Current research has conclusively demonstrated that effective
treatment can take place at any age, but the length of the treatment
period increases dramatically the longer the condition has existed
prior to treatment. Research has also demonstrated that patients with
amblyopia are more likely to sustain injuries resulting in the loss
of their good eye than individuals with two good eyes. There are many
reasons that early childhood eye examinations are essential. |
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Astigmatism
A distortion in the vision caused by irregular shape of the eye or
its components. |
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Auditory Perception
The ability to process that which is heard. Although hearing may be
perfectly normal. one may have difficulty in making sense of what
one has heard. |
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Behavioural Optometry
An international branch of optometry that specialises in the practice
of vision therapy. Behavioural optometrists (also called developmental
optometrists) will sometimes consider how environmental, nutritional
and/or behavioural factors affect visual health. The discipline is
important in rehabilitation of poorly functioning eyes. |
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Binocular
Of or involving both eyes at once. |
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Binocular skills
A term used to cover a wide range of skills requires in using the
two eyes together to help us understand our visual world. This is
a three dimensional space and includes the efficient use of the eyes
to see in 3D, (stereoscopic vision) . Difficulties in binocular skills,
including focusing, eye alignment and eye movement accuracy and efficiency
can reduce speed of processing of visual information. Sometimes people
'inhibit' or suppress the image of one eye either temporarily or on
a long term basis to avoid confusion. This can significantly reduce
understanding of text that is read and slow down cognitive (thinking)
skills. |
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Binocular Depth Perception
A result of successful stereo vision; the ability to visually perceive
three dimensional space; the ability to visually judge relative distances
between objects; a visual skill that aids accurate movement in three-dimensional
space. |
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Binocular Vision
Vision as a result of both eyes working as a team; when both eyes
work together smoothly, accurately, equally and simultaneously. |
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Binocular Vision Disability
A visual defect in which the two eyes fail to work together as a co-ordinated
team resulting in a partial or total loss of binocular depth perception
and stereoscopic vision. At least 12% of the population has some type
of binocular vision disability. Amblyopia and strabismus are the most
commonly known types of binocular vision disabilities. To find out
more about these visual conditions, see underneath. |
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Cataract
A cataract is a clouding of a part of the eye known as the crystalline
lens. The lens is a clear tissue located behind the pupil (the dark
circular opening in the middle of the iris or colored part of the
eye). The lens works with the transparent cornea, which covers the
eye’s surface, to focus light on the retina at the back of the
eye. When the lens becomes cloudy, light cannot pass to the retina
properly, and vision is blurred and decreased. More than half of all
Americans age 65 and older have a cataract. |
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Computer Related Vision Problems
With the increasing use of computers, computer related vision problems
are affecting a growing number of individuals. Visual symptoms include:
eyestrain, blurred or double vision, headaches, red or irritated eyes,
and color perception changes. Other individuals may also experience
neck or shoulder tension, general fatigue, or pain in the back, arms,
wrists or shoulders. Improper workstation set-up, a fragile eye teaming
or eye focusing system, or poor visual hygiene can aggravate these
symptoms. Individuals who suffer from computer vision syndrome may
find relief through specially designed prescription lenses, filters,
vision therapy, or adjustments to the workstation. If you experience
tension, pain, or visual discomfort when using a computer, you may
be suffering from a computer related-vision problem. |
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Convergence
The ability of both eyes to turn inwards together. This enables both
eyes to be looking at the exact same point in space. This skill is
essential to being able to pay adequate attention at near to be able
to read. Not only is convergence essential to maintaining attention
and single vision, it is vital to be able to maintain convergence
comfortably for long periods of time. For good binocular skills it
is also to be able to look further away. This is called divergence.
Sustained ability to make rapid convergence and divergence movements
are vital skills for learning. See Jump Convergence. |
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Cross Laterality
See Laterality. |
