What is the most effective way to obtain an accurate visual acuity?

Starting at the 20/20 line and working backwards is considered the most effective method to obtain an accurate visual acuity measurement. This approach allows the clinician to first establish a baseline visual ability, which is the standard against which other results are compared. By beginning at the 20/20 line, the clinician can confirm that the patient can read the letters clearly at a level known to represent normal visual acuity.

Once the 20/20 line has been established, the clinician can then assess whether the patient has any better visual acuity by moving to smaller lines. If the patient cannot read the 20/20 line, moving backwards to a larger size can help determine the limit of their visual acuity more accurately. This stepwise examination is systematic and minimizes the chances of incorrectly assessing the individual's vision, as each line read correctly provides a clearer picture of their visual capabilities.

In contrast, starting at the 20/40 line in the forward approach makes it challenging to determine whether the patient can achieve normal visual acuity, and asking the patient to simply read the smallest line may not account for any errors in reading or comprehension. Covering both eyes during the test can lead to misinterpretation of visual function, particularly if there is a difference