By Seb Della Maddalena, Manager, Therapy and Support Services
“When I first started working in vision impairment, I thought it was a narrow field (no pun intended). After a few months that perception quickly changed.
Lighting is a good example to demonstrate how varied vision impairment strategies can be. Some people with vision impairment benefit from additional lighting; some people prefer less lighting; others may benefit from a particular type of lighting; whereas of course for some people it may make no difference.
Vision impairment in childhood can be poorly understood. One reason for this is the low incidence nature of childhood vision impairment. As we now know, even within a low incidence disability group you can have such a spectrum of eye conditions and functional impact – as in the lighting example.
Unless the nature of the vision impairment is understood by professionals, their services may be of little help.
I’d like to explain what I consider the most defining aspect of childhood vision impairment – the type of vision impairment.
There are two main types of vision impairment; primary and secondary.
Primary vision impairment includes conditions of the eyes and optic nerve – referred to as ocular conditions. Some eye conditions commonly seen in children are nystagmus, optic nerve hypoplasia and retinal dystrophies. Some of these conditions present at birth, whereas other may be degenerative and discovered during childhood. Ocular conditions are generally measured by visual acuity (clarity of vision) and field loss. However, there are several other forms of measurement.
In secondary vision impairment, the issues are with the brain and involves a problem with processing visual information; referred to as cerebral vision impairment (CVI). CVI is measured by a number of defining characteristics such as: strong colour preference, preference to viewing movement, delayed visual response. Children with CVI also often have additional disabilities that stem from the brain.
There are other ways to describe the differences in primary and secondary vision impairment. However, “measurement” is perhaps the most defining and easily understood. An example is any reference to 20/20 vision – or “perfect vision” measured by visual acuity.
VisAbility recognises the need for parents, caregivers and professionals to better understand childhood vision impairment. One resource that outlines primary vision impairment is www.memyselfeye.com.au (link opens in new window).
VisAbility is currently finalising a resource package on cerebral vision impairment that will be available in the next few months.”
For more information, please contact us.