How do you interpret the test result according to Snellen chart?

Recording Snellen Results Top number equates to the distance (in metres) at which the test chart was presented (usually 6m), Bottom number identifies the position on the chart of the smallest line read by the ‘patient’. Eg; 6/60 means the subject can only see the top letter when viewed at 6m.

How do you interpret a Snellen 20/20 chart?

Visual acuity is usually measured with a Snellen chart. Snellen charts display letters of progressively smaller size. “Normal” vision is 20/20. This means that the test subject sees the same line of letters at 20 feet that person with normal vision sees at 20 feet.

How do you interpret acuity vision?

Visual acuity is expressed as a fraction.

  1. The top number refers to the distance you stand from the chart. This is often 20 feet (6 meters).
  2. The bottom number indicates the distance at which a person with normal eyesight could read the same line you correctly read.

What is considered normal vision of a Snellen eye chart?

The Snellen Chart uses a geometric scale to measure visual acuity, with normal vision at a distance being set at 20/20.

How do you measure a Snellen chart?

This is done by assessing visual acuity while looking through a pinhole. Test the eyes one at a time, beginning with the worse eye while covering the good eye. Ask the patient to begin reading letters from the top. The smallest line read represents the visual acuity.

What does a visual acuity of 6 7.5 mean?

For the Snellen chart, when assigning vision as the lowest line on which all letters were read correctly, all participants with vision of 6/7.5 or better could read a number-plate at 20 m, and no participant with worse than 6/36 was able to successfully read a number-plate (figure 1).

How do you read an optical prescription?

If the numbers are marked with a plus sign (+) or no sign, you’re farsighted. If the numbers are marked with a minus sign (-), you’re nearsighted. Some of the numbers in your prescription tell the eyeglass manufacturer how much correction your vision needs. Eyeglass strength is measured in diopters.

How do you read a Snellen chart?

The Snellen chart is a collection of letters of ever decreasing size from top to bottom. There is number below each letter and with the patient standing at six meters (this forms the numerator). The uncovered eye is formally tested by asking the patient to read the smallest series of letters. This forms the denominator.

What are the disadvantages of Snellen charts?

Unfortunately Snellen charts have several deficiencies,6,7 the most important of which is the nonlinear variation in the sizes of the letters from line to line. DAVID B. ELLIOTT, JOHN FLANAGAN, in Clinical Procedures in Primary Eye Care (Third Edition), 2007

What is the top part of the fraction in a Snellen chart?

In every Snellen eye chart analysis, the top part of the fraction is always 20. The 20 refers to the fact that the patient stood 20 feet away from the chart. In the United States, this is standard practice.

What is the difference between Bailey-Lovie and Snellen charts?

The Bailey-Lovie chart contains 14 rows, each with five letters. The size of the characters decreases from the first to the last row. The accuracy of this chart is considered superior to the Snellen chart.