Are all eye charts the same letters?
Today, there are many variations of the Snellen test. Most of them include: 11 rows of capital letters. A top row with only one letter, often a big “E.” Other letters can also be used.
What are the letters on the eye exam?
The letters used on the chart are C, D, E, F, L, N, O, P, T, and Z. When taking a vision exam, one eye is covered and you are asked to read the letters of each row aloud beginning at the top of the chart. The smallest row that you can read correctly indicates the visual acuity in the eye being tested.
How many letters can you miss on an eye exam?
20/40 (6/12) indicates that the line you correctly read at 20 feet (6 meters) away can be read by a person with normal vision from 40 feet (12 meters) away. Even if you miss one or two letters on the smallest line you can read, you are still considered to have vision equal to that line.
What vision defect is tested with the Snellen chart?
Vision (cranial nerve II) Visual acuity, which is usually assessed using a Snellen chart (Fig. 5.1). 2. Visual field testing to confrontation is a simple screen for homonymous hemianopia (an identical visual field defect due to cerebral hemisphere disease) and for sensory inattention (due to parietal lobe lesions).
What letters are not on eye chart?
The next time you are looking at an eye chart, you will notice that it does not contain every letter of the alphabet. The only letters used are C, D, E, F, L, N, O, P, T and Z.
How many letters can you have on an eye chart?
The normal Snellen chart is printed with eleven lines of block letters. The first line consists of one very large letter, which may be one of several letters, for example E, H, or N. Subsequent rows have increasing numbers of letters that decrease in size.
Are digital eye exams more accurate?
The advanced digital eye exam technology takes the guesswork out of making precise measurements. It essentially creates a fingerprint of your eye with incredible accuracy that is much more reliable than traditional eye exams.
Do you test affected or unaffected eyes first?
Note: Some people prefer to always test the right eye first. Others prefer to test the ‘worse’ eye first (ask the patient out of which eye they see best). This ensures that the minimum is read with the ‘worse’ eye, and more will be read with the ‘good’ eye.