Macular assessment using optical coherence tomography for glaucoma diagnosis

Optical coherence tomography (OCT) is an interferometry-based imaging modality that generates high-resolution cross-sectional images of the retina. Circumpapillary retinal nerve fibre layer (cpRNFL) and optic disc assessments are the mainstay of glaucomatous structural measurements. However, because these measurements are not always available or precise, it would be useful to have another reliable indicator. The macula has been suggested as an alternative scanning location for glaucoma diagnosis. Using time-domain (TD) OCT, macular measurements have been shown to provide good glaucoma diagnostic capabilities. Performance of cpRNFL measurement was generally superior to macular assessment. However, macular measurement showed better glaucoma diagnostic performance and progression detection capability in some specific cases, which suggests that these two measurements may be combined to produce a better diagnostic strategy. With the adoption of spectral-domain OCT, which allows a higher image resolution than TD-OCT, segmentation of inner macular layers becomes possible. The role of macular measurements for detection of glaucoma progression is still under investigation. Improvement of image quality would allow better visualisation, development of various scanning modes would optimise macular measurements, and further refining of the analytical algorithm would provide more accurate segmentation. With these achievements, macular measurement can be an important surrogate for glaucomatous structural assessment.