Should diabetic patients be screened for glaucoma?

Untreated primary open angle glaucoma (POAG) is a blinding optic neuropathy. Timely medical or surgical treatment is eVective in slowing the rate of optic nerve damage and delaying the onset of visually disabling field loss, but treatment is only eVective in prevention, and there is as yet no means of reversing established axon loss. In the United Kingdom, around 250 000 people suVer from POAG with visual field loss. 3 The disease accounts for 15% of the 1500 new registrations for blindness in England and Wales per year. 5 The insidious nature of POAG, its potential detection by relatively simple, non-invasive, screening tests at an early stage, and the existence of treatments eVective at preventing disabling visual loss constitute a cogent argument for screening. Consistently, over many years and in numerous diVerent populations, researchers have found that 50% of the disease remains undetected in the community, and one in five of those with newly confirmed disease already have advanced field loss. Clearly, new approaches to the detection of POAG are required if we detect only half the prevalent disease. To target individuals at increased risk would appear to constitute sound clinical and economic practice. 9 The “Guidelines for the management of ocular hypertension and primary open angle glaucoma” recently published by the Royal College of Ophthalmologists, define risk factors for the development of POAG. These include a positive family history in a first degree relative, high myopia, black race, and diabetes. These groups would therefore appear suitable for targeted screening. The purpose of this review is to examine the evidence that one of these factors, diabetes mellitus, is a risk factor for POAG. It is recommended that all people with diabetes should receive annual screening for diabetic retinopathy, and if there truly is an association between diabetes and POAG, it is tempting to speculate that annual assessment should include a measurement of intraocular pressure (IOP) and that all newly diagnosed glaucoma patients should receive a random blood glucose test. Related areas of controversy including the protective influence of elevated pressure in the development of diabetic retinopathy and the suggestion that diabetic patients may have an excess risk of primary angle closure glaucoma are beyond the scope of this review.