Layer-by-layer analysis of macular diseases with objectively measured visual functions.

New methods were developed to measure layer-by-layer visual function in macular diseases objectively and quantitatively. A prototype apparatus for foveal cone densitometry that combines a modified fundus camera, independent optic pathways and a personal computer was assembled. Using a two-way density technique, the density and regeneration time of the foveal cone pigment can be measured objectively. Data on layer-by-layer visual function can be obtained when a-wave, b-wave and oscillatory potentials are recorded by focal macular electroretinography (FMERG). Since the retinal origin of each component is different, the comparative measurement of these components indicates which layer of the macula is disturbed. The simultaneous recording of FMERG and visual evoked response (VER) might be useful in determining which part of the visual pathway is impaired. These methods of measurement were reviewed and some examples of layer-by-layer analysis were shown.