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Two main ocular responses can be distinguished: vergence of eyes, and accommodation. Both of these mechanisms are crucial in stereoscopic vision. Vergence or independent inward/outward rotation of eyes is engaged to fixate on objects and perceive them as single. Incorrect vergence response can cause double vision.
The Brock string is commonly employed during treatment of convergence insufficiency and other anomalies of binocular vision. It is used to develop skills of convergence as well as to disrupt suppression of one of the eyes. [1] During therapy, the one end of the Brock string is held on the tip of the nose while the other is tied to a fixed point.
Stereopsis, or stereo vision, is the visual blending of two similar but not identical images into one, with resulting visual perception of solidity and depth. [ 21 ] [ 22 ] In the human brain, stereopsis results from complex mechanisms that form a three-dimensional impression by matching each point (or set of points) in one eye's view with the ...
The TNO random dot stereotest (short: TNO stereo test or TNO test) is similar to the randot stereotest but is an anaglyph in place of a vectograph; that is, the patient wears red-green glasses (in place of the polarizing glasses used in the randot stereotest). Like other random dot stereotests, the TNO test offers no monocular clues. [4]
Subjective Refraction is a technique to determine the combination of lenses that will provide the best corrected visual acuity (BCVA). [1] It is a clinical examination used by orthoptists, optometrists and ophthalmologists to determine a patient's need for refractive correction, in the form of glasses or contact lenses. The aim is to improve ...
Patients who have accommodative spasm may benefit from being given glasses or contacts that account for the problem or by using vision therapy techniques to regain control of the accommodative system. Possible clinical findings include: Normal Amplitude of accommodation; Normal Near point of convergence; Reduced Negative relative accommodation
Thus, in this case the convergence of the rays transmitted by a lens is equal to the radius of the light source divided by its distance from the optics. This limits the size of an image or the minimum spot diameter that can be produced by any focusing optics, which is determined by the reciprocal of that equation; the divergence of the light ...
Also relatively common is the Titmus Fly Stereotest, a greatly enlarged stereoscopic image of a fly used by optometrists and ophthalmologists to determine if patients, especially young children, have normal stereoscopic vision. Currently available vectographic vision training aids, marketed under the registered trademark name "Vectogram ...