WGA consensus glaucoma definition

Structural changes in the optic nerve detected by optical coherence tomography (OCT) can in themselves provide sufficient information for a diagnosis of glaucoma, even in the absence of visual field changes, according to a report from the 10th World Glaucoma Association (WGA) Consensus Meeting on the Diagnosis of Primary Open Angle Glaucoma (POAG). “Detecting progressive retinal nerve fibre layer (RNFL) glaucomatous thinning and neuroretinal rim narrowing are the best currently available gold standards for a glaucoma diagnosis,” said Robert N Weinreb MD, Hamilton Glaucoma Center and Shiley Eye Institute, University of California, San Diego, USA, in a presentation at the 12th European Glaucoma Society Congress in Prague, Czech Republic. He noted that the consensus guidelines also state that OCT may be the best currently available digital imaging instrument for detecting and tracking optic nerve structural damage in glaucoma. The guidelines state that RNFL thickness and macular retinal ganglion cell loss OCT measurements provide complementary information on the status of the optic nerve. Dr Weinreb noted that perimetry is indispensable for documentation and monitoring of functional decline in glaucoma, and perimetric defects that correspond to structural findings increase the likelihood of the disease. It is the opinion of the WGA consensus committee that, while the diagnosis of glaucoma does not always require the detection of visual field defects with perimetry, visual field loss is present in the great majority of patients with glaucoma. Other points agreed at the WGA’s Consensus Meeting include the importance of distinguishing between the structural changes of the optic nerve that occur with age and those occurring in glaucoma. In addition, the guidelines note that it is difficult to diagnose glaucoma on a structural basis in highly myopic eyes. Therefore, the use of reference normative databases is not appropriate for diagnosing glaucomatous damage in such cases. Instead, documented progressive optic neuropathy should be used to make the differential diagnosis, Dr Weinreb said. FUNCTION MOST IMPORTANT The WGA consensus guidelines also stress that, while structural change can provide the diagnosis of POAG, it is the functional change that has the most impact on patients, said David F Garway-Heath MD, FRCOphth, Moorfields Eye Hospital, London, UK. “Visual loss related to POAG affects patients' ability to perform daily activities and also their vision related quality of life,” he said. The guidelines advise that a glaucoma hemifield test (GHT) criterion ‘outside normal limits’, or ‘borderline’, increases the probability that an eye has glaucoma. The level of probability for the disease also depends on the presence and magnitude of other risk factors for the disease, such as raised intraocular pressure and family history, the consensus guidelines state. Robert N Weinreb: rweinreb@ucsd.edu David F Garway-Heath: david.garway-heath@moorfields.nhs.uk

Tags: glaucoma diagnosis, optic nerve, optical coherence tomography