blind spot The existence of a small blind region in the normal human eye was predicted in the seventeenth century by the French scientist Edmé Mariotte. While dissecting a human eye, Mariotte noticed the ‘optic disc’ — a hole in the back of the eyeball through which all the nerve fibres that make up the optic nerve leave the eye. He realized that, unlike the rest of the retina that surrounds the hole, this optic disc is devoid of light-sensitive photoreceptors. Applying his knowledge of optics and of the anatomy of the eye, he deduced that every eye should be blind in a corresponding small portion of the visual field. The optic disc lies about 15 degrees ...