Parameters
The percentage of vision that the person retains, also called ‘residual vision’, is defined by two parameters: acuity and visual field.
Acuity: ability to distinguish shapes and objects at a certain distance.
Visual Field: angle of view of each eye. Because of low vision, it can be reduced peripherally or vertically; in the central area or randomly in the form of spots.
Low vision can affect people in many different ways depending on the combination of these two parameters that manifest differently depending on the cause from which they originate.
Visual Acuity
Visual Field
Causes and Effects
Cataracts and Optic Nerve Hypoplasia (ONH) cause loss of visual acuity.
Macular Degeneration and Stargardt Disease affect the central field of vision.
Diabetic Retinopathy creates random distribution spots.
Retinitis Pigmentosa and Glaucoma cause loss of peripheral visual field.
Hemianopia can be caused by vascular accidents or trauma and causes the loss of the upper or lower visual field.
Albinism is related to loss of contrast.