PMC

(a) Illustration of the probability that the deflection occurrence due to the insertion angle is within the acceptable deflection (blue area) (b) Example of calculated deflection probability (orange line) and deflection probability distribution (blue line) to deflection slope φ_i in an insertion angle at θ_i.

φ_dif is divided in bins of 10 angular degrees. For healthy participants, this is the difference between left and right deflection angle.

(Color online) Conditional-averaged velocity field [Eq. ()] near the glottis and Re = 408 case during the early phase of the glottal cycle: (a) positive deflection angle for the ψ = 10° case, (b) negative deflection angle for the ψ = 10° case, (c) positive deflection for the ψ = 0° case, and (d) negative deflection angle for the ψ = 40° case.

Notations. NP is the nodal point of the eye. It is convenient to trace rays from NP out, rather than in the direction light travels. The angle sign convention is that clockwise rotation from the normal to the surface is positive, as illustrated in the circle. The prism apex angle is α. PG is the primary gaze direction (the head direction). β is the angle of rotation of the first refracting surface from the normal to PG. β = 0 for OPS and β = α for EPS. When we describe a shifted image viewed through the prism, gaze direction and retinal eccentricity have to be considered. Although the deflection at the gaze point is determined by the angle of incidence at the gaze point, the deflection angle (δ) at each other retinal eccentricity (θ´) depends on the angle of incidence at that eccentricity. The figure illustrates a gaze shifted left from PG to an arbitrary (and negative) gaze angle θ_G. The retinal eccentricity of the ray shown in red is θ´, while its angle from PG is θ (so θ = θ' - θ_G). φ is the resulting angle of incidence of the ray at the first refracting surface. φ = θ + β. An angle of incidence φ at the first refracting surface results in prism deflection angle δ relative to φ and visual angle V relative to PG. The deflection angle δ_A and visual angle V_A at the apex edge are determined by the angle of incidence at the apex. As explained later, we measure gaze angles from NP, not the eye’s center of rotation.