One of several types of chromamatopsy or vision disturbance with some non-existent coloration, caused by problems in the retina or optic nerve. The xantopsia, from the Greek xanthos, yellow color and opsis opseos, vision. This yellowish vision that van Gogh appears to have suffered can be caused by consumption of the digitalis purplish, prescribed by his doctor, Dr. Gachet, in whose portrait appears the yellow tones and a thimder.
