Test: Visual Acuity Test

Video Link

Background/Purpose

Visual acuity (VA) is a measure of the ability of the eye to distinguish shapes and the details of objects at a given distance. It is important to assess VA in a consistent way in order to detect any changes in vision. One eye is tested at a time.

Procedure

Ensure good natural light or illumination on the chart. It is important to ensure that the person has the best possible chance of seeing and reading the test chart as treatment decisions are made based on the results of VA testing.

If the test is done outdoors, the chart should be in bright light and the patient in the shade, with enough light to illuminate the patient's face during the test.

Explain the procedure to the patient. Tell patients that it is not a test that they have to pass, but a test to help us know how their eyes are working. Tell them not to guess if they cannot see.

Ensure that any equipment that the patient touches is clean and is cleaned between patients. Infections can be passed between patients if equipment – or the testers' hands – are not clean.

Position the patient, sitting or standing, at a distance of 6 meters from the chart. The patient can hold one end of a cord or rope of 6 meters long to ensure that the distance is maintained

Test the eyes one at a time, at first without any spectacles (if worn).

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. This means that no letters are remembered, which could make the second visual acuity appear better than it is.
Performed: Unilaterally

Dialog

Visual acuity, also known as clarity of vision or sharpness of vision, refers to a person's ability to see small details.

Criteria

• Clarity of vision

Measurement

20

LOINC Code

28631-0

Scale/Grading

selection range; grade - LOINC ID
Option - Value option selection range; grade - LOINC IDPass ; Pass - Fail ; Fail -