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Light from a single point of a distant object and light from a single point of a near object being brought to a focus. The accommodation reflex (or accommodation-convergence reflex) is a reflex action of the eye, in response to focusing on a near object, then looking at a distant object (and vice versa), comprising coordinated changes in vergence, lens shape (accommodation) and pupil size.
In this, distances vary for individuals from the far point—the maximum distance from the eye for which a clear image of an object can be seen, to the near point—the minimum distance for a clear image. Accommodation usually acts like a reflex, including part of the accommodation-convergence reflex, but it can also be consciously controlled.
Clinically, accommodative convergence is measured as a ratio of convergence, measured in prism diopters, to accommodation, measured in diopters of near demand. The patient is instructed to make a near target perfectly clear and their phoria is measured as the focusing demand on the eye is changed with lenses.
Argyll Robertson pupils (AR pupils) are bilateral small pupils that reduce in size on a near object (i.e., they accommodate), but do not constrict when exposed to bright light (i.e., they do not react). They are a highly specific sign of neurosyphilis; however, Argyll Robertson pupils may also be a sign of diabetic neuropathy.
The pupillary reflex results in the pupil constricting (left) and dilating (right) These include the pupillary light reflex and accommodation reflex . Although the pupillary response , in which the pupil dilates or constricts due to light is not usually called a "reflex", it is still usually considered a part of this topic.
Both of these mechanisms are neurally linked forming the accommodation-convergence reflex [1] of eyes. One can distinguish vergence distance — a distance of a point towards which both eyes are converging, and an accommodation distance — a distance of a region in space towards which the focus or refractive power of the ...
Dilation and constriction of the pupil Pupillary response is a physiological response that varies the size of the pupil between 1.5 mm and 8 mm, [ 1 ] via the optic and oculomotor cranial nerve. A constriction response ( miosis ), [ 2 ] is the narrowing of the pupil, which may be caused by scleral buckles or drugs such as opiates / opioids or ...
Light falling in one eye affects the diameter of the pupils in both eyes. One can easily see this by looking at a friend's eye while he or she closes the other: when the other eye is open, the pupil of the first eye is small; when the other eye is closed, the pupil of the first eye is large. Accommodation and vergence. Accommodation is the ...