Home Distance Vision Assessment Aid

The aim of the Home Distance Vision Assessment Aid project is to develop an accurate and low cost way to measure vision at home. It is currently a research tool – be aware that it is not yet a validated test of vision. You should only access this website if you have been directed to.


Contents


About

Measuring distance vision at home is difficult, and there are few clinically validated and reliable methods of doing so. Digital solutions, including smartphone and tablet apps, provide a potential solution, but risk excluding those without access to these devices. We aim eventually to produce a vision test that can be printed on A4 paper by the patient, or by the care provider and posted to the patient.

Please be aware that the tests you can generate using this site are under development, and not validated for clinical use. We are currently exploring how reproducible the test is on different printers, and following that hope to determine how well vision measured in this way relates to vision measured on traditional tests of vision. We are grateful for feedback on how consistent the print size of the test is by comparison of the silhouette on page 2 of the printout to a credit card.

If you do decide to use these printouts during a video consultation, for example, please consider them only as an aid as you might ask a patient in clinic to read some text to assess their visual performance. They are not validated tests of acuity.

For information on the performance of the test, please see the pre-print on medrxiv.


Downloads

This site allows the generation of two different aids:

If the person taking the test cannot reliably identify letters, you should download the symbol test. If you're using the symbol test, you should practice the symbols using this document.

1. Standardised assessment aids

Download (Letters, Standardised)

Download (Symbols, Standardised)

2. Randomised assessment aids

Each time you need to repeat the test, click the correct link below to download a new version of the test sheet. This means that the order of the letters will be changed each time you perform the test.

Telephone assessment

These assessment aids can be identified using a simple 6 digit code that can easily be given over the telephone. They do not contain as many random combinations of letters as the postal/self assessment tests, but there are expected to be enough combinations of letters to be sufficient for several years of weekly testing.

Download (Letters, Telephone)

Download (Symbols, Telephone)

Postal/self assessment

These assessment aids have over a billion possible letter orderings. Each sheet is identified using a longer code (16 digits). This code contains information about the type of test being administered, the correct answers, and a code which allows us to check for errors.

Download (Letters, Self-Assessment)

Download (Symbols, Self-Assessment)


Patient instructions

Download the version of the test that your clinician tells you to, and print it.

Make sure to select "Full Size" or "100%" in the print settings when you're printing.

  1. Check the chart size is correct by placing a bank card in the box on the second page. If you can hide the grey box but still see all of the black outline, the size is correct.
  2. Fix this chart to a wall using Blu-Tac, at about eye level
  3. Stand 150 cm (1.5 m or about 5 feet) away from the chart. (Use the string provided to measure this distance)
  4. Follow the instructions given by the clinician on the telephone

Clinician instructions

The basic structure of the test is the same, regardless of which option you choose.

1. Choosing an assessment aid

If you are testing a patient only once or twice: you should use the standardised test downloads from above. These are always the same, so you can know the correct answer.

If you are testing a patient multiple times AND checking their answers during the test using telephone/video call: you or the patient should use the telephone assessment from above. Using this assessment, the patient can give you a 6 character code over the phone, which you can enter into this web page to view the correct answers. This allows you to have the correct answers in front of you when the patient is reading the chart over the phone.

If you are testing a patient multiple times AND asking them to self-check their answers, or post their answers in: you should use the self-assessment test downloads from above. Each test is identified by a 16 character code. This code allows you to identify the correct answers. To view the correct answers from a code, you should enter the code into this web page.

2. Using the assessment aid

You should typically administer the test from 150cm, providing the patient with a pre-measured string to use for measuring this distance.

At 150cm, the lines equate to 3/60, 6/60, 6/30, 6/15, 6/7.5.

At 190cm, the lines equate to 6/96, 6/48, 6/24, 6/12, 6/6.

If different parts of your clinic use different distances for testing, it is recommended that you colour code the string given to patients, using one colour per distance. This should be checked before each trial.

3. Viewing answer sheets

To mark answers from a patient, please use the link below and enter their test code to view the correct answers.

View answer sheets

4. Scoring tests

To score the vision of your patient, please select below the viewing distance used for the test. Then, enter the number of letters correctly read.




Correct:

Feedback and queries


References

Crossland MD, Dekker TM, Hancox J, Lisi M, Wemyss TA and Thomas, PBM. Remote vision testing: Validation of a simple home-printable vision screening test for telemedicinePreprint, 2020. medrxiv.

Hamm LM, Yeoman JP, Anstice N, Dakin SC. The Auckland Optotypes: An open-access pictogram set for measuring recognition acuity. J Vis. 2018 Mar 1;18(3):13. PMID: 29677328


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