Role of blue on yellow and low luminance achromatic mfVEP in preperimetric glaucoma, and their structural and functional correlates

Glaucoma is a progressive optic neuropathy characterized by a specific pattern of optic disc damage and ganglion cell loss. It is one of the leading causes of blindness in the world. The gold standard for the diagnosis of glaucoma is the detection of characteristic optic disc changes and identification of visual field loss on Standard Automated Perimetry (SAP), which is subjective and often unreliable. It is also evident that due to the redundancy of the visual system, there exists a time gap in the detection of structural versus functional glaucomatous changes. The use of multifocal visual evoked potential (mfVEP) to objectively detect glaucomatous visual field defects has been well demonstrated. Building on this, a Blue on Yellow mfVEP (BonY mfVEP) that targets the Koniocellular pathway and Low Luminance Achromatic mfVEP (LLA mfVEP) that targets the Magnocellular pathway of the visual system have been developed. The sensitivities of these specialized multifocal techniques have also been recently studied. This project seeks to establish the long-term changes associated with these objective perimetry tests and identify the role of both BonY and LLA mfVEP as potential markers in the detection of pre-perimetric glaucoma to establish alternative methods to standard perimetry techniques that offer early detection of functional visual loss. Furthermore, establishing a relationship between these mfVEP techniques to other subjective perimetry techniques and high resolution retinal imaging techniques will help decide on a combination of structural and functional tests that will optimally detect change early as no single test appears to be definitely superior to others.