Asymptomatic and 50% of Sufferers Not Diagnosed
Glaucoma is a condition that results in loss of nerve fibres within one or both optic nerves. Whilst it is normal to lose optic nerve fibres at a slow and steady rate as part of normal ageing, with glaucoma this rate of loss is abnormally accelerated. Eventually loss of nerve fibres can lead to a reduction in vision, typically affecting the peripheral visual field early and then coming towards the centre of vision as it becomes more advanced.
In many cases of glaucoma, there are few or no symptoms early on. As a result there are many individuals with glaucoma who are not aware they have it. Studies both in Australia and overseas consistently show that approximately 50% of cases of glaucoma within the community remain undiagnosed for this reason. Attempts to identify these cases through screening have been largely ineffective to date because the sensitivity/specificity of testing is poor (as is the case with intra-ocular pressure testing) or it has not been cost effective. Currently new cases are detected opportunistically (ie: when a consultation with an eye care professional is conducted for another reason) or by examining select groups of individuals at high risk (eg: positive family history, previous eye injury, very long or short sighted).