Search results
Results from the WOW.Com Content Network
The Bates method is an ineffective and potentially dangerous alternative therapy aimed at improving eyesight.Eye-care physician William Horatio Bates (1860–1931) held the erroneous belief that the extraocular muscles caused changes in focus and that "mental strain" caused abnormal action of these muscles; hence he believed that relieving such "strain" would cure defective vision.
This early and traditional form of vision therapy was the foundation of what is now known as orthoptics and was based on observation not research or evidence. [38] In the first half of the twentieth century, orthoptists, working with ophthalmologists, introduced a variety of training techniques mainly designed to improve ocular alignment. In ...
Visual or vision impairment (VI or VIP) is the partial or total inability of visual perception.In the absence of treatment such as corrective eyewear, assistive devices, and medical treatment, visual impairment may cause the individual difficulties with normal daily tasks, including reading and walking. [6]
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).
Mesopic vision occurs in intermediate lighting conditions (luminance level 10 −3 to 10 0.5 cd/m 2) [citation needed] and is effectively a combination of scotopic and photopic vision. This gives inaccurate visual acuity and color discrimination. In normal light (luminance level 10 to 10 8 cd/m 2), the vision of cone cells dominates and is ...
LASIK surgery is performed by an ophthalmologist who uses a femtosecond laser or a microkeratome to create a corneal flap to expose the corneal stroma and then an excimer laser to reshape the corneal stroma in order to improve visual acuity. [2] [3] LASIK is very similar to another surgical corrective procedure, photorefractive keratectomy (PRK ...
Distribution of rods and cones along a line passing through the fovea and the blind spot of a human eye [1]. A blind spot, scotoma, is an obscuration of the visual field.A particular blind spot known as the physiological blind spot, "blind point", or punctum caecum in medical literature, is the place in the visual field that corresponds to the lack of light-detecting photoreceptor cells on the ...
A Snellen chart is an eye chart that can be used to measure visual acuity.Snellen charts are named after the Dutch ophthalmologist Herman Snellen who developed the chart in 1862 as a measurement tool for the acuity formula developed by his professor Franciscus Cornelius Donders.