Individualised Visual field progression observations in glaucoma

This is a single centre, interventional, longitudinal study comparing several methods of evaluating the status of the visual field in people with glaucoma. Visual field assessments of peripheral vision will be compared to several forms of ophthalmic imaging. Current clinical visual field testing procedures for glaucoma use the same regularly spaced test grid for all people. The intervention to be tested is a visual field testing grid that is customised for the specific individual being tested (for example, to avoid retesting locations in visual space that are known to be blind, and to instead test areas along the border of these regions). This study will compare whether customised testing grids are better able to observe progressing damage to the visual field than the current approach of using the same test grid for all (known as the 24-2 testing grid). The study will also relate measured visual field status and progression rates to structural biomarkers of glaucoma measured with ophthalmic imaging. Specifically, the study will measure visual fields using a 24-2 test pattern and using the Australian Reduced Range Extended Spatial Test (ARREST) (Turpin, Morgan et al. 2018, Muthusamy, Turpin et al. 2020), which customises the stimulus placement. Each of these tests take approximately 5-8 minutes to complete per eye and will be conducted on the Compass perimeter hardware (CentreVue, SpA, Italy). The Compass perimeter is a commercially available visual field testing machine. Participants look into the machine, and press a button every time they see a small white light appear anywhere in their visual field. In addition to the visual field tests, the study will collect: a) structural Optical Coherence Tomography (OCT) image of the optic nerve, retinal nerve fibre layer, and macular regions using the Spectralis OCT (Heidelberg Engineering, GmBH, Germany) : b) OCT angiography measures of the optic nerve and macular regions to non-invasively estimate blood flow (using the Spectralis OCT; c) retinal photography using the Compass Perimeter; d) two additional measures of visual function: 1) macular ON-OFF pathway function (measured using a customised test on an iPad; and 2) an estimate of individual psychometric function slope for Size III perimetric targets in normal regions of visual field (measured using custom software on the Compass Perimeter hardware). All imaging methods (OCT, OCT Angiography and retinal photograph) are well accepted clinical assessments that each take no more than 2 minute to collect (including set-up time, imaging acquisition is a few seconds). Participants sit in a darkened room and view a fixation target while the images are acquired. The ON-OFF pathway test involves looking a a chequered pattern on an iPad and pressing a button on the tablet to indicate whether 1, 2 or 3 dark or light targets are seen embedded in the chequered pattern. This test takes approximately 5 minutes. In total, the study visit will take approximately 90 minutes. The study will observe the natural history of glaucomatous progression using these different methodologies. Measurements will be taken (visual fields using the standard and customised test patterns, and ophthalmic imaging) every 4 months for 3 years. ON-OFF pathway function and psychometric function slope will only be measured at the first and last visit. Tests will be conducted by AHPRA registered optometrists or trained ophthalmic technicians.