An ophthalmic error measurement system includes a projecting optical system delivering light onto a retina of an eye, a pre-correction system which compensates a light beam to be injected into the eye for aberrations in the eye, the pre-correction system being positioned in between the projecting optical system and the eye, an imaging system which collects light scattered by the retina, and a detector receiving light returned by the retina from the imaging system. Use of the pre-correction system allows the end-to-end aberrations of the ocular system to be analyzed. The use of a pre-correction system also allows use of a minimized spot size on the retina, and all of its attendant advantages.