Description
Recent randomised controlled trials have demonstrated unequivocally that glaucoma is a treatable disease. The ability to produce a sustained reduction in intra-ocular pressure has been found both to reduce the number of ocular hypertensives that convert to glaucoma, and the number of glaucomas that show white on white visual field progression. The inevitable tidying up process that will follow these landmark studies will focus on the degree of the intra-ocular pressure reduction, the ability to eliminate fluctuations, the ability to maintain compliance and persistence on behalf of the patients, and the avoidance of adverse reactions.
Amid this aura of self congratulation, it is easy for healthcare providers to lose sight of the principal issues around glaucoma blindness in the United Kingdom. Specifically, despite our best efforts, there are still as many glaucomas undiagnosed as those receiving treatment at the present time. A corollary from this is that many patients are mis-diagnosed as suffering from glaucoma as those who truly have the disease. The increased confidence that comes from favourable outcomes with glaucoma treatment should now lead the healthcare community towards creating better methods of targeting those at risk. What methods are available to better deliver glaucoma healthcare to those in the population who need it most?
It is recognised that certain sub sets of the population run a higher risk than the remainer. Glaucoma targets adults, it is more likely to target certain ethnic groups (African-Caribbeans and perhaps those of Indian descent). It is more likely to target those with certain co-morbidity (high myopia, cardiovascular disease, and certain self-medications). Optometrists are, and should remain, the principal identifiers of glaucoma in the community. The challenge is to facilitate their making the diagnosis and to enhance their ability to manage patients.
At the present time, patients self select optometric visits because of perceived eye symptoms. Yet glaucoma rarely creates symptoms until late in the disease. It is necessary, therefore, to set up a system whereby glaucoma can be seen and diagnosed pre symptomatically by the community optometrist. The most appropriate method would be by targeting patients within the General Practitioners surgery.
The General Practitioner, by training, time, and perhaps inclination, is reluctant to diagnose asymptomatic eye disease without considerable help. They would fail to refer patients in their most treatable stages to the optometrist. What is required are semi-automatic methods within the General Practitioners surgery akin to the high street sphygmomanometer or tell your weight machine, that can pick up reduced visual function and/or raised intra-ocular pressure.
Pilot studies using semi-automatic case finding methods of visual function (such as flicker, or FDT) have demonstrated the ability of these machines to identify patients at risk. In an increasingly well educated society where attendance at the General Practitioner “Well Man / Woman” clinic is increasingly the norm, then the inclusion of such devices would spot individuals with early disease. The sensitivity would need to be set high even though this would be at the expense of specificity. However, for a disease with relatively low prevalence, this would mean overwhelming numbers who would be identified for further examination. Patients, who test positive on these self test methods, would then be referred by the General Practitioner to the community optometrist for a further examination.
What examination methods should be made available to the optometrist today? The International Glaucoma Association has been trail blazing with its insistence on the trio of tests, namely tonometry, fundoscopy and perimetry. Todays diagnostic trio should keep tonometry but should replace white on white perimetry with one of the new methods of posterior segment examination. The GDxVCC or the HRT II are both capable of identifying early structural change at the optic nerve head and could be used for the purpose of diagnosis. Such abnormality could then result in referral to the hospital eye services, or a clinical optometrist with management skills, where a full ocular examination and treatment as appropriate would be given.
The approach that has been outlined above would remove the self selection bias and capture the asymptomatic “well” patient. It is only by identifying this group in the community that the silent undiagnosed 50% of glaucoma patients have a reasonable chance of early diagnosis.
