‘Low Vision’ and Your Eye Condition
What do we mean by the term ‘low vision’?
A person is said to have low vision when their eyesight is limited or impaired and cannot be corrected with conventional glasses or contact lenses.
They have a visual acuity of less than 6/18, or they have a visual field of less than 20 degrees across. People are not legally allowed to drive with these vision measurements. Vision tests are conducted by eye care specialists, who include: optometrists, ophthalmologists and orthoptists. If you have been diagnosed with an eye condition and you have been advised by your eye care specialist that you are still allowed to drive, we can still provide you with information about services that may be of benefit now or in the future, if your vision deteriorates.
Guide Dogs Tasmania (GDT) also provides services to people who have lost vision as a result of eye disease or trauma, acquired brain injury, congenital conditions and stroke.
Low Vision Conditions
Vision loss may be caused by disease or trauma affecting the eye and/or the brain.
Here is a list of the most common low vision conditions:
- Macular Degeneration (MD) is the name given to a group of degenerative diseases of the retina that cause progressive, painless loss of central vision, affecting the ability to see fine detail, drive, read and recognise faces. For more information refer to www.mdfoundation.com.au
- Glaucoma is the name given to a group of eye diseases in which the optic nerve at the back of the eye is slowly destroyed. In some people this damage is due to an increased pressure inside the eye – a result of blockage of the circulation of aqueous, or its drainage. In other patients the damage may be caused by poor blood supply to the vital optic nerve fibres, a weakness in the structure of the nerve, and/or a problem in the health of the nerve fibres themselves. For more information refer to www.glaucoma.org.au
- Cataract is a cloudy area on the eye’s lens, formed when protein in the lens is damaged and clumps together. The clouding limits the amount and clarity of light passing through the lens to the retina, causing poor vision. There are three forms of cataract. For more information refer to www.cera.org.au (fact sheets)
- Diabetic Retinopathy is a complication of diabetes mellitus that damages blood vessels inside the retina at the back of the eye. It commonly affects both eyes and can lead to vision loss if it is not treated. There are three forms of diabetic retinopathy. For more information refer to www.cera.org.au (fact sheets).
- Retinitis Pigmentosa is the name of a group of inherited retinal dystrophies that cause degeneration of the retina of the eye. The retina, at the back of the eye, is a thin sheet of interconnected nerve cells including the light sensitive cells (rods and cones). It is here that light is converted into electrical signals to the brain where “seeing” takes place. In RP the rod and cone cells degenerate. Depending on the type of RP, the rate of progression varies. There is no cure at this time. For more information refer to www.retinaaustralia.com.au.
- Homonymous Hemianopia affects the right halves or the left halves of the visual fields of both eyes. Often it is due not to any pathology in the eye itself but to damage to the optic nerve or visual parts of the brain.