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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 ...
Exterior of labyrinth of the inner ear. Benign paroxysmal positional vertigo ( BPPV) is a disorder arising from a problem in the inner ear. [ 3] Symptoms are repeated, brief periods of vertigo with movement, characterized by a spinning sensation upon changes in the position of the head. [ 1] This can occur with turning in bed or changing ...
003429. In medicine, the caloric reflex test (sometimes termed 'vestibular caloric stimulation ') is a test of the vestibulo-ocular reflex that involves irrigating cold or warm water or air into the external auditory canal. This method was developed by Robert Bárány, who won a Nobel prize in 1914 for this discovery.
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 ...
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 ...
Purpose. whether a person has strabismus. In the fields of optometry and ophthalmology, the Hirschberg test, also Hirschberg corneal reflex test, is a screening test that can be used to assess whether a person has strabismus (ocular misalignment). A photographic version of the Hirschberg test is used to quantify strabismus.
In the most familiar acuity test, a Snellen chart is placed at a standard distance: 6 metres. At this distance, the symbols on the line representing "normal" acuity subtend an angle of five minutes of arc, and the thickness of the lines and of the spaces between the lines subtends one minute of arc. This line, designated 6/6 (or 20/20), is the ...