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Geographic atrophy is a chronic disease, which leads to visual function loss. This often results in difficulties performing daily tasks such as reading, recognizing faces, and driving, and ultimately has severe consequences on independence. [ 8][ 9][ 10] Initially, patients often have good visual acuity if the GA lesions are not involved in the ...
Nystagmus. Nystagmus is a condition of involuntary (or voluntary, in some cases) [1] eye movement. [2] People can be born with it but more commonly acquire it in infancy or later in life. In many cases it may result in reduced or limited vision. [3] In normal eyesight, while the head rotates about an axis, distant visual images are sustained by ...
The eyes of the patient can then easily be observed for which kind (horizontal, vertical, or diagonal) of nystagmus is present, to determine which semicircular canal (horizontal, superior, or posterior) is affected. The Dix–Hallpike test is a common test performed by examiners to determine whether the posterior semicircular canal is involved ...
The eyes then turn toward the ipsilateral ear, with horizontal nystagmus to the contralateral ear. [5] [6] Absent reactive eye movement suggests vestibular weakness of the horizontal semicircular canal of the side being stimulated. In comatose patients with cerebral damage, the fast phase of nystagmus will be absent as this is controlled by the ...
Parinaud's syndrome is a cluster of abnormalities of eye movement and pupil dysfunction, characterized by: Paralysis of upwards gaze: Downward gaze is usually preserved. This vertical palsy is supranuclear, so doll's head maneuver should elevate the eyes, but eventually all upward gaze mechanisms fail. In the extreme form, conjugate down gaze ...
Horizontal optokinetic nystagmus. The optokinetic reflex ( OKR ), also referred to as the optokinetic response, or optokinetic nystagmus (OKN), is a compensatory reflex that supports visual image stabilization. [ 1] The purpose of OKR is to prevent image blur on the retina that would otherwise occur when an animal moves its head or navigates ...
Electronystagmography. Electronystagmography ( ENG) is a diagnostic test to record involuntary movements of the eye caused by a condition known as nystagmus. It can also be used to diagnose the cause of vertigo, dizziness or balance dysfunction by testing the vestibular system. [ 1] Electronystagmography is used to assess voluntary and ...
Gravitropism (also known as geotropism) is a coordinated process of differential growth by a plant in response to gravity pulling on it. It also occurs in fungi. Gravity can be either "artificial gravity" or natural gravity. It is a general feature of all higher and many lower plants as well as other organisms.