  The incorporation of structured light techniques into vision science has
enabled more selective probes of polarization related entoptic phenomena.
Diverse sets of stimuli have become accessible in which the spatially dependant
optical properties can be rapidly controlled and manipulated. For example, past
studies with human perception of polarization have dealt with stimuli that
appear to vary azimuthally. This is mainly due to the constraint that the
typically available degree of freedom to manipulate the phase shift of light
rotates the perceived pattern around a person's point of fixation. Here we
create a structured light stimulus that is perceived to vary purely along the
radial direction and test discrimination sensitivity to inwards and outwards
radial motion. This is accomplished by preparing a radial state coupled to an
orbital angular momentum state that matches the orientation of the dichroic
elements in the macula. The presented methods offering a new dimension of
exploration serve as a direct compliment to previous studies and may provide
new insights into characterizing macular pigment density profiles and assessing
the health of the macula.
