Abstract
In Vision Research, 119, 73-81, 2016, I constructed a family of circular horopters that pass through anatomically located optical nodes and the fixation point in the horizontal visual plane. For any given vergence, corresponding horopters intersect at the point of symmetric convergence on the Vieth--Müller circle, such that a vertical line through this point yields the horoper's vertical component. In that study, the fovea was incorrectly assumed to be located at the posterior pole.
Here, I model the longitudinal horopters by combining binocular geometry with a novel asymmetric eye model that includes the fovea's temporalward displacement from the posterior pole and the crystalline lens' tilts and decentrations that tend to compensate for various types of aberration. The resulting family of horopter curves are conics resembling empirical horopters, their geometry fully specified by the eye model's asymmetry. The values of the lens' asymmetry parameter in the range of the measured lens' tilt and decentration in healthy eyes produce values of the abathic distance in the range observed in human binocular vision.
My results corroborate the model introduced on an ad hoc basis by Ogle in 1932 for the forward gaze and extended by Amigo in 1965 to any horizontal gaze by demonstrating that their conics are nearly identical to the more anatomically accurate conics simulated here.
I conclude by discussing a possible relation to research on vergence resting position during degraded visual conditions as the abathic distance and resting vergence position distance have a similar range and average value.