By 2010, glaucoma will affect 60 million people worldwide and cause blindness in more than 8 million.1 Despite the availability of effective treatments that delay or halt progression of the disease, an unacceptable number of people with glaucoma remain undiagnosed and untreated. Strategies for achieving earlier and more accurate diagnosis of glaucoma are therefore urgently needed to combat the rising burden of this disease in an ageing European population.
The challenge of early glaucoma detection
Studies in industrialized countries, including the recent Thessaloniki Eye Study, a population-based study in Greece,2 have consistently shown that as many as 50% of glaucoma cases are undiagnosed.3-5 There are several reasons for this:
Current screening methods are ineffective
In the Thessaloniki Eye Study, for example, glaucoma patients who had not seen an eye care specialist during the previous year had a six-fold increase in the odds of being undiagnosed compared with patients who had visited an eye care specialist during the previous year. In addition, the Visual Impairment Project, a population-based study in Australia, found that a high proportion of individuals had undiagnosed glaucoma despite having seen an ophthalmologist (33%), optometrist (53%), or both (14%) in the preceding year.9 It is therefore clear that, in addition to publicizing the benefits of regular eye checks to the public, improved training of eye care professionals and standardization of examination protocols are essential in order to enhance glaucoma detection rates.
Increasingly, detection of early structural changes to the optic disc and retinal nerve fibre layer, which may precede subsequent visual field abnormalities, is also seen as a key strategy in achieving earlier and more accurate diagnosis of glaucoma. Current approaches to structural assessment are often reliant on examination and photography of the optic disc. Whilst an essential component of the ophthalmic examination, these methods sometimes lack the sensitivity, objectivity and reproducibility needed to detect the subtle structural changes that occur in early stage glaucoma.