6.1 Background

   6.1.1 Classification of disease

'Glaucoma' is a term that covers a heterogeneous group of conditions that have in common an irreversible, and usually progressive, optic neuropathy, characterised by distinctive patterns of structural change at the optic nerve head (ONH) and by distinctive patterns of loss of visual function (visual field loss). The glaucomas include primary open-angle glaucoma (POAG, high- and normal-pressure types), acute and chronic angle-closure glaucoma, and secondary glaucomas. Most glaucoma is associated with raised intraocular pressure.

  6.1.2 Disease prevalence

POAG (the most common form in the UK) increases in prevalence with increasing age. Around 1% of white subjects has POAG at the age of 50 years, rising to around 4% at the age of 80 years. Estimates for black subjects are 3% and 13% at the equivalent ages. In the context of the ageing population the prevalence of glaucoma will rise. POAG is asymptomatic early in the course of the disease, and patients frequently present late with irreversible loss of vision. Glaucoma is the most common cause of irreversible blindness in the world, and a leading cause of blindness in the UK. In the United States, it has been estimated that 4% of white Americans and 8% of black Americans with glaucoma are blind in both eyes.

  6.1.3 Cost of glaucoma morbidity

In the UK, the annual cost associated with blindness due to glaucoma probably exceeds £100 million. The real impact of the disease is almost certainly greater, since visual field loss can have a profound impact on the quality of life of the affected patient, such as loss of the driving licence, even when visual acuity is relatively unaffected. In addition, treatments given for glaucoma whether they are surgical or medical (drops) can further reduce the patient's quality of life. The importance of glaucoma to the individual is the impact of suffering a chronic disease and the functional limitation resulting from loss of vision, which may be postponed or prevented by early diagnosis and appropriate treatment.

Once glaucoma is diagnosed, a patient has to be followed for the rest of his/her life. At present, between a quarter and a third of all patients attending ophthalmology clinics have glaucoma. This proportion, and the number of patients, is set to increase as the population ages.

  6.1.4 Funding perspective

In the US, the National Eye Institute spends approximately $30 million US dollars a year on glaucoma research for a population of 250 million. This contrasts with approximately $0.5 to 1.0 million spent by charitable organisations in the UK for a population of 60 million. Investment in glaucoma research in the UK is likely to be productive given the characteristics of the UK population and the international standing of its medical and scientific researchers. The combination of a structured health service and a population willing to participate in medical research is essential for the study of a chronic progressive disease such as glaucoma. The strength of glaucoma research in the UK, manifest by the large number of papers in high-impact peer-reviewed journals and the strong presence of UK glaucoma specialists presenting research at international scientific meetings, is much greater than would be expected from the current levels of funding. Investment in UK glaucoma research is required if this international lead is to be maintained.

   6.2 Research Potential