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The cover test is used to determine both the type of ocular deviation and measure the amount of deviation. The two primary types of ocular deviations are the tropia and the phoria. A tropia is a misalignment of the two eyes when a patient is looking with both eyes uncovered.
The results leading on from the cover test will give you an indication of the type of deviation and which way you should hold your prism for the next stage of the test. Either BASE IN for an exodeviation (eye turned out), BASE OUT for an esodeviation (eye turned in), BASE UP for a hypodeviation (eye turned down) or BASE DOWN for a ...
The test involves observation of the suspect's pupil as it follows a moving object, noting lack of smooth pursuit, distinct and sustained nystagmus at maximum deviation, and; the onset of nystagmus prior to 45 degrees. The horizontal gaze nystagmus test has been highly criticized and major errors in the testing methodology and analysis found.
Heterophoria is the misalignment of the visual axis such that one or both eyes are not properly fixated to an object of interest. When the visual axis is misaligned in such a way, it is corrected by the fusional vergence system. Diagnosis. The cross-cover test, or alternating cover test is usually employed to detect heterophoria.
Convergence insufficiency. Convergence Insufficiency. Other names. Convergence disorder. Specialty. Ophthalmology, optometry. Convergence insufficiency is a sensory and neuromuscular anomaly of the binocular vision system, characterized by a reduced ability of the eyes to turn towards each other, or sustain convergence .
A typical test would be to place the eraser of a pencil on the roof of a lesion and spin the pencil in a rolling motion between the thumb and forefinger. If the lesion is opened (i.e., skin sloughed off), then the Nikolsky's sign is present/positive.
Prism dioptres. Prism correction is commonly specified in prism dioptres, a unit of angular measurement that is loosely related to the dioptre. Prism dioptres are represented by the Greek symbol delta (Δ) in superscript. A prism of power 1 Δ would produce 1 unit of displacement for an object held 100 units from the prism. [2]
A sample GSR signal of 60 seconds duration. Electrodermal activity ( EDA) is the property of the human body that causes continuous variation in the electrical characteristics of the skin. Historically, EDA has also been known as skin conductance, galvanic skin response (GSR), electrodermal response (EDR), psychogalvanic reflex (PGR), skin ...
If the patient saw a red line to the right and white light to the left, they are said to have esotropia or esophoria (uncrossed diplopia) in which base out (BO) prisms of increasing strength are used until the lines are superimposed.
Positive: when the test results in a wheal of 5–10 mm diameter, reaching its peak in 4–7 days. The control arm shows no reaction. This indicates that the subject lacks antibodies against the toxin and hence is susceptible to the disease. Pseudo-positive: when there is only a red-colored inflammation and it disappears within 4 days. This ...