Structure and function in glaucoma remain difficult

The relationship between structure and function in glaucoma remains difficult for a variety of reasons, according to Michele Iester MD, Italy, who discussed the issue during ESCRS Glaucoma Day 2015 in Barcelona. Glaucoma is characterised by the loss of retinal ganglion cells (RGCs) and the retinal nerve fibre layer (RNFL), which results in both structural and functional changes, he explained. However, the exact nature of the relationship between structure and function in glaucoma remains uncertain, and is currently the subject of continuing research. Key issues are the variation in anatomy and function among the population, fluctuation of measurements, as well as variation in methods of assessment and scaling systems, Dr Iester reported. That aside, previous studies have reported that combining functional tests with structural tests can improve the diagnostic accuracy for glaucoma over one test alone, he noted, quoting data on existing structure-function systems. What is now apparent is that, in early glaucoma, structural loss appears greater than functional loss, while in more advanced disease, function changes at a greater rate than structure, Dr Iester outlined. He also quoted the World Glaucoma Association Consensus (WGA 2011), which says that structural and functional examination should be done during the patient follow-up; and that imaging and visual field assessments are fundamental to help make decisions for glaucoma treatment and to assess the rate of progression. Concluding, Dr Iester said in the future more sensitive systems to detect ganglion cell numbers or function might change the relationship.