Directional effects of the retina appearing in the aerial image

Abstract

The subjective measurement of the Stiles-Crawford effect is uneasy in the retinal periphery with inexperienced subjects; so an objective method for determining the direction of the human photoreceptors is presented. Interference fringes are projected onto the retina in Maxwellian view, then the beam reflected by the retina is bounded by a small diaphragm in the exit pupil. The modulation depth of the fringes in the plane conjugate with the retina is measured: this modulation varies greatly when the angles of incidence and reflection on the outer segments are modified, hence giving the direction of the photoreceptors.