Abstract: The invention features a three path Maxwellian view optical system by which a stimulus test pattern may be ophthalmoscopically placed on small portions of the central 70.degree. of the retina of an eye. In alternative embodiments, different test patterns may be used to obtain data relating to flash ERG, pattern ERG (PERG), or flicker photomerry. The location of the stimulus test target on the retina may be tracked and recorded by a spectral perimetry system. The invention further provides a spectral sensitivity measurement system in which electrorctinogram (ERG) data is collected, transmitted, processed, and displayed or stored.