Role of the Macular Optical Coherence Tomography Scan in Neuro-Ophthalmology

Abstract

Recent improvements in optical coherence tomographic (OCT) resolution and automated segmentation software have provided a means of relating visual pathway damage to structural changes in the retinal nerve fiber layer (RNFL) and corresponding soma of the ganglion cells in the inner layers of the macula and also in the outer photoreceptor layer in the macula. Studies correlating retinal structure with function are reviewed in the context of OCT in optic nerve and retinal disorders. Recently published work provides evidence showing a strong relationship not only between the RNFL and visual threshold in optic nerve disorders but also between visual sensitivity and the inner layers of the retina in the macula, where the cell bodies of ganglion cells reside. Acquired and genetic disorders affecting the outer retina show correlation between visual sensitivity and the thickness of the outer photoreceptors. These relationships help localize unknown causes of visual field loss through segmentation of the retinal layers using spectral domain OCT. Advances in relating the structure of the ganglion cell layer in the macula to the corresponding axons in the RNFL and to visual function further our ability to differentiate and localize ambiguous causes of vision loss and visual field defects in neuro-ophthalmology. Ganglion cell layer analysis in volume OCT data may provide yet another piece of the puzzle to understanding structure-function relationships and its application to diagnosis and monitoring of optic nerve diseases, while similar structure-function relationships are also being elucidated in the outer retina for photoreceptor diseases.