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The largest letter on an eye chart often represents an acuity of 6/60 (20/200), the value that is considered "legally blind" in the US. Many individuals with high myopia cannot read the large E without glasses, but can read the 6/6 (20/20) line or 6/4.5 (20/15) line with glasses.
In the expression 6/x vision, the numerator (6) is the distance in metres between the subject and the chart and the denominator (x) the distance at which a person with 6/6 acuity would discern the same optotype. Thus, 6/12 means that a person with 6/6 vision would discern the same optotype from 12 metres away (i.e. at twice the distance).
Near visual acuity or near vision is a measure of how clearly a person can see nearby small objects or letters.Visual acuity in general usually refers clarity of distance vision, and is measured using eye charts like Snellen chart, LogMAR chart etc. Near vision is usually measured and recorded using a printed hand-held card containing different sized paragraphs, words, letters or symbols.
Cedric Jones – American football player, blind in one eye. [88] Masood Jan – Blind cricketer, holds the record for highest individual score in a Blind ODI [89] Shekhar Naik – Blind cricketer. [90] Jake Peavy - Former Major League Baseball pitcher, legally blind without corrective lenses; Marla Runyan – Legally blind Olympic and ...
The human eye is a sensory organ in the visual system that reacts to visible light allowing eyesight. Other functions include maintaining the circadian rhythm, and keeping balance. Arizona Eye Model. "A" is accommodation in diopters. The eye can be considered as a living optical device.
Degrees of vision loss vary dramatically, although the ICD-9 released in 1979 categorized them into three tiers: normal vision, low vision, and blindness.Two significant causes of vision loss due to sensory failures include media opacity and optic nerve diseases, although hypoxia and retinal disease can also lead to blindness.
Contributing to vision, the retina contains the photosensitive rod and cone cells and associated neurons. To maximise vision and light absorption, the retina is a relatively smooth (but curved) layer. It has two points at which it is different; the fovea and optic disc. The fovea is a dip in the retina directly opposite the lens, which is ...
Hypotony may occur either due to decreased production of aqueous humor or due to increased outflow. Hypotony has many causes including post-surgical wound leak from the eye, chronic inflammation within the eye including iridocyclitis, hypoperfusion, tractional ciliary body detachment or retinal detachment. [5]