Relating optical coherence tomography to visual fields in glaucoma: structure-function mapping, limitations and future applications.

Combining information from optical coherence tomography (OCT) imaging and visual field testing is useful in the clinical assessment and monitoring of patients with glaucoma. Measurements of retinal nerve fibre layer thickness or neuroretinal rim width taken around the optic nerve head may be related to the visual field using a structure-function map. In this review, the structure-function mapping methods in clinical use are discussed. Typical clinical maps provide a population average, 'one size fits all' representation, but in recent years methods for customising structure-function maps to individual eyes have been developed and these are reviewed here. In the macula, visual field stimuli stimulate photoreceptors for which associated retinal ganglion cells are peripherally displaced. Recently developed methods that relate OCT measurements to visual field test locations in the macula are therefore also reviewed. The use of structure-function maps to relate OCT measurements to localised visual field sensitivity in new applications is also explored. These new applications include the selection of visual field test locations and stimulus intensities based on OCT data, and the formal post-test combination of results across modalities. Such applications promise to exploit the structure-function relationship in glaucoma to improve disease diagnosis and monitoring of progression. Limitations in the validation and use of current structure-function mapping techniques are discussed.