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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.
Accommodation usually acts like a reflex, including part of the accommodation-convergence reflex, but it can also be consciously controlled. The main ways animals may change focus are: Changing the shape of the lens. Changing the position of the lens relative to the retina. Changing the axial length of the eyeball. Changing the shape of the cornea.
The symptoms and signs associated with convergence insufficiency are related to prolonged, visually demanding, near-centered tasks. They may include, but are not limited to, diplopia (double vision), asthenopia (eye strain), transient blurred vision, difficulty sustaining near-visual function, abnormal fatigue, headache, and abnormal postural adaptation, among others.
However, errors in this relationship can cause problems, such as hyperopic individuals having a tendency for crossed eyes because of the over exertion of their accommodation system. Clinically, accommodative convergence is measured as a ratio of convergence, measured in prism diopters, to accommodation, measured in diopters of near demand.
Gaze-stabilising movement may include the vestibulo-ocular reflex and optokinetic reflex, and gaze-shifting mechanisms as saccades and pursuit movements. Vergence movement or convergence is the movement of both eyes to make sure that the image of the object being looked at falls on the corresponding spot on both retinas.
Incorrect vergence response can cause double vision. Accommodation is the eye’s focusing mechanism and it is engaged to produce a sharp image on a retina. Both of these mechanisms are neurally linked forming the accommodation-convergence reflex [1] of eyes.
Bezold-Jarisch reflex — involves a variety of cardiovascular and neurological processes which cause hypopnea and bradycardia. Biceps reflex — a jerking of the forearm when the biceps brachii tendon is struck with a tendon hammer, stimulating the C5 and C6 reflex arcs. Blushing — a reddening of the face caused by embarrassment, shame, or ...
Convergence insufficiency is a common problem with the eyes, and is the main culprit behind eyestrain, blurred vision, and headaches. [9] [unreliable source?] This problem is most commonly found in children. Near point of convergence (NPC) is measured by bringing an object to the nose and observing when the patient sees double, or one eye ...