Question

Conduct a search on Google for recent news articles about visual acuity measurement or skin infections. Summarize the article in 300 words and include the source.

Answer 1

A standard eye chart is necessary to make comparisons and to record people’s visual acuity. The most common chart used in most doctors’ offices is the .Snellen eye chart In 1862, a Dutch Ophthalmologist, Dr. Hermann Snellen, devised this eye chart. He determined that there was a relationship between the sizes of certain letters viewed at certain distances.The Snellen eye chart has a series of letters or letters and numbers, with the largest at the top. As the person being tested reads down the chart, the letters gradually become smaller. Many other versions of this chart are used for people who cannot read the alphabet. The Tumbling E chart has the capital letter “E” facing in different directions and the person being tested must determine which direction the “E” is pointing, up, down, left, or right.

For early Treatment of Diabetic Retinopathy Study,ETDRS chart is used.

For children who are not able to read letters picture chart is used.Broken wheel vision test is one of those.Pictures of broken wheel on the cars is used.

The Snellen fractions, 20/20, 20/30, etc., are measures of sharpness of sight.They give no information about seeing larger objects and objects with poor contrast (such as steps and curbs); it also does not inform us as to whether or not meaning is obtained from visual input, how much effort is needed to see clearly or singly, and whether or not vision is less efficient when using both eyes as opposed to each eye individually. In short, visual acuity measures only the smallest detail we can see; it does not represent the quality of vision in general.

If a subject needs letters (or symbols) that are twice as large or twice as close as those that can just be seen by a standard eye, visual acuity is said to be 1/2 (or an equivalent fractional value, such as 20/40, 6/12, etc.). If the magnification need is 5x, visual acuity is 1/5 (20/100, 6/30, etc.), and so on.

When checking visual acuity, one eye is covered at a time and the vision of each eye is recorded separately, as well as both eyes together. In the Snellen fraction 20/20, the first number represents the test distance, 20 feet. The second number represents the distance that the average eye can see the letters on a certain line of the eye chart. So, 20/20 means that the eye being tested can read a certain size letter when it is 20 feet away. If a person sees 20/40, at 20 feet from the chart that person can read letters that a person with 20/20 vision could read from 40 feet away. The 20/40 letters are twice the size of 20/20 letters; however, it does not mean 50% vision since 20/20 sounds like it is one half of 20/40. If 20/20 is considered 100% visual effiency, 20/40 visual acuity is 85% efficient.

If a patient sees 20/200, the smallest letter that they can see at 20 feet could be seen by a normal eye at 200 feet. This is the Snellen Acuity (English). In Metric Acuity, 20/20 equals 6/6. The conversion is that 20 feet equals approximately 6 meters (actually 6.096).

Metric 6/3 6/4.5 6/6 6/7.5 6/9 6/12 6/15 6/30 6/60

Snellen 20/10 20/15 20/20 20/25 20/30 20/40 20/50 20/100 20/200

For people who have worse than 20/400 vision, a different eye chart can be used that measures beyond 20/400 vision, or, for the most accurate measurements, a Low Vision Chart can be moved closer to the patient to measure the smallest letter that they can see at a lesser distance. It is common to record vision worse than 20/400 as Count Fingers (CF at a certain number of feet), Hand Motion (HM at a certain number of feet), Light Perception (LP), or No Light Perception (NLP). The conversion of Snellen Acuity to Count Fingers Acuity is as follows:

20/800 20/1000 20/1143 20/1333 20/1600 20/2000 20/2666 20/4000 20/8000

CF10′ (Count Fingers at ten feet) CF 8′ CF 7′ CF 6′ CF 5′ CF 4′ CF 3′ CF 2′ CF 1′

https://lowvision.preventblindness.org/2003/10/06/how-visual-acuity-is-measured/. This is the link of reference used in this.