How does Snellen eye chart work?

Description. The normal Snellen chart is print with eleven lines of block letters. A person taking the test covers one eye from 6 metres or 20 feet away, and reads aloud the letters of each row, beginning at the top. The smallest row that can be read accurately indicates the visual acuity in that specific eye.Click to see full answer. Consequently, how do you score a Snellen eye 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.Similarly, what line should you be able to read on an eye chart? A 3 to 4-year-old should be able to read the 20/40 line, and a 5-year-old the 20/30 line. Older children and adults should be able to read the majority of letters on the 20/20 line. If you notice any results that fall outside these standards, be sure to schedule an eye exam with your Vision Source doctor. Also Know, how do you do a Snellen test? Procedure Ensure good natural light or illumination on the chart. Explain the procedure to the patient. Wash and dry the occluder and pinhole. Test each eye separately – the ‘bad’ eye first. Position the patient, sitting or standing, at a distance of 6 metres from the chart. Are all Snellen eye charts the same?In some cases a standard Snellen eye chart cannot be used. The tumbling E chart has the same scale as a standard Snellen eye chart, but all characters on the chart are a capital letter “E,” in different spatial orientations (rotated in increments of 90 degrees).