PHYSICAL EYE CONDITIONS

Acuity

Clearness of vision. Standard is 6/6 which means the individual sees at 6 metres what they should see at that distance. Metric equivalent of 20/20 vision.

Accommodation

Ability to change and control the focussing of the eye.

Astigmatism

Condition where vision is distorted because the front of the eye is not totally spherical ie. it is shaped more like a rugby ball than a soccer ball. Clear vision is restored by an appropriate lens.

Binocular

Using both eyes together.

Convergence

Turning of the eyes inward to see closer.

Fusion

Ability to perceive objects seen with the two eyes as a single object.

Hyperopia

Long-sightedness. It is easier to see in the distance than close up. A small amount of long-sightedness is normal in children but may affect their comfort and concentration at close distances ie. reading and writing.

Myopia

Short-sightedness. It is easier to see close up than in the distance.

Motilities

Movement of the eyes following a moving target.

Multifocal

A lens with an upper area for seeing in the distance and a lower area with a different prescription for close work.

Perception

Interpreting the information received by the eyes.

Plus Lens

(Convex) Changes the path of light so that it focuses closer. Given to correct long-sightedness.

Minus Lens

(Concave) Changes the path of light so that focus is farther away. Given to correct short-sightedness.

Refractive Condition

Long-sightedness (hyperopia), short-sightedness (myopia) and astigmatism (see above).

Stereopsis

Ability to see depth and judge distance.

Vergence

Turning of the eyes to see singly at a given distance.

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VISUAL PERCEPTION SKILLS

Perception is the capacity to interpret or give meaning to what is seen. The following are specific perception skills. A "form" is a piece of visual information like a letter, number or shape.

Visual Discrimination

The ability to match or determine exact characteristics of two forms when one of them is among similar forms ie. "find the pair".

Visual Memory

The ability to remember for immediate recall (after 4-5 secs) all of the characteristics of a given form and being able to find this form from an array of similar forms.

Visual Spatial Relationships

The ability to determine from among five forms of identical configuration the one single form or part of single form that is going in a different direction from the other forms.

Visual Form Consistency

The ability to see a form and to find that form even though the form may be smaller, larger, rotated and/or hidden.

Visual Sequential Memory

The ability to remember for immediate recall a series of forms from among four separate series of forms.

Visual Figure Ground

The ability to perceive a form visually, and to find this form hidden in a conglomerated ground of matter eg. "Where's Wally".

Visual Closure

The ability to determine, from among four incomplete forms the one that is the same as the stimulus form (the completed form).

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