# Visual Acuity Testing

## Overview

This module describes how to test a patient’s visual acuity.

## Indications

## Contraindications

## Patient information and consent

Always verify your patient’s identity and obtain informed consent before proceeding.

### How do I explain this procedure?

“I need to test your eyes to see if your vision is sharp or reduced.”

### What can my patient expect?

“Stand six meters from a chart on the wall. Close one eye with an occluder or the palm of your hand. Do not put pressure on your eye, because it will influence your vision. Read the letters on the chart out loud. They will become smaller and harder to read with each passing line. I will use the point where you can no longer read the letters correctly to determine your vision. We will then repeat the test with the other eye.”

### What is my patient’s role?

“Read each line to me as I point to it. Do not squint, because this can affect the results. If you use glasses for far vision, take them off first, and then we will repeat the test with them on. I will also ask you to look through a small hole in an occluder/piece of carton. Make sure you line up your eye correctly so that you can see the letters on the chart and then read the letters again from the top. We will repeat the test again for the other eye.”

## Preparation

### Documentation

### Equipment

## Site & Positioning

Position the patient six meters from the Snellen chart, in good lighting.

## Procedure

Follow medical asepsis without gloves.

## Troubleshooting

My patient cannot read the chart at 6 m.

Follow the sequence below and report the best result. Stand at 3 m and report vision as 3/60 = 6/120 etc. If unable to read the chart, test counting of fingers (report as CF) at 3 m, and at 1 m (for example, CF 3 m or CF 1 m). If unsuccessful, test perception of hand movement (report as HM). If unsuccessful, test light perception by shining a bright torch in the eye (report as LP). If unable to perceive light, report as NPL.

My patient is a child.

Children from the age of 2 can use an E chart, pointing in the direction of the legs of each E being read. Used from the age of 3, the Sheridan-Gardiner test is a child-friendly test. Children younger than 2 can be tested by holding a toy 30-50 cm from their face and looking for fixation and following, with one eye occluded at a time. If there is no response, use a torch.

My patient is worried that her baby can’t see.

Ask the mother if her baby looks at her while feeding. A baby that can see usually makes eye contact with the mother. If not, refer immediately to ophthalmology.

## Risks

## References