an optotype projector apparatus provided with variable contrast , and having a large variety of optotypes and matrices for providing tests for stereoscopic vision of chromatic balance and comprising a projector for producing contrasting variations of the optotype images operating on the basis of two complementary light sources , one provided by a primary body and the other provided by a secondary body , both of which are remotely controlled so that by diminishing the intensity of one source , a consequent increase of the other source takes place . the primary body is provided with a ferrule for controlling the movement of a guide to focus an objective lens , and the primary body emits a first light beam towards the objective lens along a first axis , the secondary body emits a second light beam along a second axis , a beam controller directs the second light beam through the objective lens along the first axis onto a specific area of the screen , and the optotypes are moved past the path of the first light beam to vary the optotype projected onto the screen , and the matrix is moved past the first light beam .