Relative directions of excitation and photoreceiving optical systems are so set that an angle formed by optical axes thereof in the air is 14 DEG , and an eyeball is fixed in such a direction that its ocular axis divides the angle formed by the optical axes into two equal parts. On a light incidence side of a one-dimensional solid-state image pickup device of the photoreceiving optical system, a slit is arranged for inputting measuring light components generated from portions of the eyeball having different depth positions on an excitation light beam in photoelectric conversion elements of different positions of the image pickup device. The measuring light components generated from the respective portions of the eyeball parallel to the optical axis are incident upon the one-dimensional solid-state image pickup device through the slit and simultaneously detected, so that the positions of the photoelectric conversion elements and measuring light component generating positions at the eyeball correspond to each other.
Measuring apparatus for intraocular substance employing light from eyeball