You don’t always need specialist equipment to get a basic indication of how clearly you can see. A simple at-home vision test using a Snellen eye chart can help you check your distance vision and identify whether one eye may be seeing differently from the other.
At Centre for Sight, we have created a free downloadable guide that you can use to check your eyes at home.
What is a Snellen eye chart?
A Snellen chart is the familiar eye chart made up of rows of letters that gradually become smaller.
It is used to measure visual acuity; in simple terms, how clearly you can see detail at a set distance.
You may recognise measurements such as 20/20 vision, which are commonly used to describe visual acuity.
How can I test my eyesight at home?
To carry out a simple home vision check:
- Download and print the Snellen chart on A4 paper, following the printing instructions provided.
- Place the chart somewhere well lit and at eye level.
- Measure 2.8 metres from the chart and stand at this distance.
- Cover your left eye without pressing on it.
- Read down the chart and note the smallest line you can comfortably read.
- Repeat the test while covering your right eye.
- Record the result for each eye separately.
What does 20/20 vision mean?
20/20 is a measure of visual acuity, rather than a statement that your eyes are completely healthy. Having 20/20 vision means you can see a certain level of detail at the standard testing distance. It does not mean that every aspect of your vision or eye health is normal. This is one reason an at-home eye test should never be considered a replacement for a professional eye examination.
What if one eye is worse than the other?
Testing your eyes individually can make differences between them easier to notice. If one eye cannot read the same line as the other, or your vision appears to have changed since your last eye examination, it is worth arranging a professional assessment. Changes in vision can have many causes, from a change in prescription to conditions affecting the eye itself. A comprehensive examination can help establish what is causing the difference.
Can an online or home eye test tell me if my eyes are healthy?
No. A home vision test can tell you something about how clearly you can see, but it cannot assess the overall health of your eyes.
Many aspects of eye health cannot be checked with a Snellen chart alone. A professional examination may include assessment of the front and back of the eye, eye pressure and other diagnostic tests depending on your individual needs. Think of your home test as a useful check rather than a diagnosis.
When should I have my eyes professionally checked?
If you have noticed that road signs are becoming harder to read, television subtitles aren’t as clear, night driving feels different, or one eye appears clearer than the other, these are all good reasons to have your vision assessed. You should also continue to have regular eye examinations even if you feel your vision is good, as not every eye condition causes noticeable symptoms in its early stages.
When not to rely on a home vision test
A Snellen chart should not be used to assess an urgent eye problem. Seek prompt professional advice if you experience a sudden loss or significant change in vision, severe eye pain, a new shower of floaters or flashing lights, a curtain or shadow across your vision, or a significant eye injury.
At Centre for Sight, our expert consultants use the most advanced technology to provide accurate diagnoses and offer life-changing treatments for laser vision correction, cataracts, keratoconus, retinal conditions, and more.
