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When measuring horizontal fusion ranges, base in prisms assess fusional divergence while base out prisms assess fusional convergence. The vertical fusional vergence amplitude can also be measured with base up and base down prisms although the horizontal PFR is typically the main focus when testing.
The prism cover test (PCT) is an objective measurement and the gold standard in measuring strabismus, i.e. ocular misalignment, or a deviation of the eye. It is used by ophthalmologists and orthoptists in order to measure the vertical and horizontal deviation and includes both manifest and latent components.
Cylinders are placed into trial frame vertically, making the two red lines horizontal; Vertical prism ( base-up, or base-down) can also be added into the trial frames to separate the two red lines (This avoids confusion if the patients claim that they only see one red line).
Its prism has 2n vertices, 3n edges, and 2 + n faces. Take a polyhedron with V vertices, E edges, and F faces. Its prism has 2V vertices, 2E + V edges, 2F + E faces, and 2 + F cells. Take a polychoron with V vertices, E edges, F faces, and C cells. Its prism has 2V vertices, 2E + V edges, 2F + E faces, 2C + F cells, and 2 + C hypercells ...
Their vertical components are transmitted (shown), while the horizontal components are absorbed and reflected (not shown). Because their polarization vectors depend on incidence angle, polarizers based on Fresnel reflection inherently tend to produce s – p polarization rather than Cartesian polarization [ clarification needed ] , which limits ...
The misalignment may be vertical, horizontal or both. The misalignment (a few minutes of arc ) is much smaller than that of strabismus . While strabismus prevents binocular vision , fixation disparity keeps binocular vision, however it may reduce a patient's level of stereopsis .
In astronomy, geography, and related sciences and contexts, a direction or plane passing by a given point is said to be vertical if it contains the local gravity direction at that point. [1] Conversely, a direction or plane is said to be horizontal (or leveled) if it is perpendicular to the vertical direction.
This line is called the empirical horizontal horopter. There is also an empirical vertical horopter, which is effectively tilted away from the eyes above the fixation point and towards the eyes below the fixation point. The horizontal and vertical horopters mark the centre of the volume of singleness of vision.
In projective geometry, a cylinder is simply a cone whose apex (vertex) lies on the plane at infinity. If the cone is a quadratic cone, the plane at infinity (which passes through the vertex) can intersect the cone at two real lines, a single real line (actually a coincident pair of lines), or only at the vertex.
Brewster's angle (also known as the polarization angle) is an angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with no reflection. When unpolarized light is incident at this angle, the light that is reflected from the surface is therefore perfectly polarized.