Jargon buster

At Guide Dogs we occasionally use technical language to describe eye conditions that you may not initially understand, but sometimes it’s necessary to provide the full picture and point you towards more resources. If you’re unsure of the meaning of any terms, this glossary will help you to decipher what’s what.

Accommodation   The ability of the lens in your eye to change shape to focus on objects at different distances. 
Bilateral vision loss   When you have vision loss affecting both eyes.
Binocular vision  The ability of both eyes to work together at the same time and enable depth perception.
Congenital   The word to describe any condition present at birth.
Contrast sensitivity    The ability to perceive the difference between an object and its background (usually tested by distinguishing different shades of grey from one another).
Depth perception    The ability to judge distance and spatial relationships of objects.
Field of vision    The total area that you can see around you without shifting your gaze, including your central area of focus and peripheral vision.
Focal point   The point on the retina where light rays meet and give you your most detailed vision.
Functional vision   The ability to use eyesight in everyday conditions.
Light adaptation   The ability of the eye to adapt vision to different levels of lighting.
Low vision aids (LVAs)   Aids like magnifiers that you can use to improve your functional vision.
Monocular vision   When you can see through one eye only.
Occlusion (patching)   The practice of covering one eye to develop sight in the other (lazy) eye.
Peripheral vision   Everything you can see around you at the edge of your detailed central vision.
Pigmentation   Colouring usually associated with skin or hair.
Refraction   The process that measures eyes for long or short sight or astigmatism.
Refractive error   A defect of the eye that prevents light rays focussing on the retina and causes long or short sight: correctable in most cases with glasses.
Unilateral vision loss   When you have vision loss affecting one eye.
Visual acuity   A measure of your ability to see fine detail; often called central vision.
Visual perception   The ability to give meaning and understanding to what you have seen (not just to see it).

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