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Their disagreement concerned the innate vs. learned aspect of binocularly coordinated eye movements. Helmholtz's arguments were mainly related to Listing's law and can be simplified as the fact that there exist positions of the eyes where muscles will have different effects on the two eyes. Thus Hering's law, in its original formulation, simply ...
It is a type of vergence eye movement and is done by extrinsic muscles. Diplopia, commonly referred to as double vision, can result if one of the eye's extrinsic muscles are weaker than the other. This results because the object being seen gets projected to different parts of the eye's retina, causing the brain to see two images.
The trochlear nerve controls the superior oblique muscle to rotate the eye along its axis in the orbit medially, which is called intorsion, and is a component of focusing the eyes on an object close to the face. The oculomotor nerve controls all the other extraocular muscles, as well as a muscle of the upper eyelid.
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.
The extraocular muscles, or extrinsic ocular muscles, are the seven extrinsic muscles of the eye in humans and other animals. [1] Six of the extraocular muscles, the four recti muscles, and the superior and inferior oblique muscles, control movement of the eye. The other muscle, the levator palpebrae superioris, controls eyelid elevation.
If the patient's eyes are aligned and is bifoveal, the shifting of the image caused by the prism will produce a movement towards the apex of the prism (of the eye under the prism), and the fellow eye will have an outward movement in the same direction of the same magnitude due to Hering's law of equal innervation. Simultaneously the fellow eye ...
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.
The physiologic basis of the head tilt test was explained by Alfred Bielschowsky and Hofmann [8] in 1935. [9] However, Nagel described it 30 years prior to Bielschowsky when he noted that the combined action of the superior rectus muscle and the superior oblique muscle of one eye and of the inferior rectus and inferior oblique muscles in the fellow eye causes incycloduction and excycloduction ...