A person came to eye OPD for routine eye check u. On snellen’s cha he was found to read 6/6. At what distance he should be able to read 6/24
**Core Concept**
The Snellen chart is a widely used visual acuity test that measures a person's ability to read letters at a standard distance. The chart is calibrated to measure visual acuity at 6 meters, with each line representing a decrease in visual acuity.
**Why the Correct Answer is Right**
To determine the distance at which a person with 6/6 visual acuity can read 6/24, we need to understand the relationship between visual acuity and distance. The ratio 6/6 indicates that the person can read letters at 6 meters that are 6 meters away from the standard eye chart. Similarly, the ratio 6/24 indicates that the person can read letters at 6 meters that are 24 meters away from the standard eye chart. To find the distance at which the person can read 6/24, we need to calculate the distance at which the 6/24 line would be equivalent to the 6/6 line on the standard chart. This can be done by multiplying the standard distance (6 meters) by the ratio of the two visual acuities (6/24 divided by 6/6).
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not take into account the relationship between visual acuity and distance.
**Option B:** This option is incorrect because it does not use the correct ratio of visual acuities to calculate the distance.
**Option C:** This option is incorrect because it does not consider the standard distance of 6 meters on the Snellen chart.
**Clinical Pearl / High-Yield Fact**
When using the Snellen chart, it's essential to ensure that the patient is seated at the standard distance of 6 meters and that the chart is illuminated to the recommended level. Additionally, the patient should be wearing their corrective lenses if they have any.
**Correct Answer:** 96 meters. A person with 6/6 visual acuity should be able to read 6/24 at a distance of 96 meters.