Vision Science Research Group

Visual Acuity

These web pages have been set up primarily to inform patients, parents, teachers, carers and other professionals who have received visual acuity details relating to children with visual impairment. They have been developed in response to questions from parents and others working with visually impaired children regarding what these children can be expected to see.

If you have a recorded visual acuity (e.g. 6/60 or 20/200) these web pages should allow you to obtain a printout of the size of images that you should be able to see easily at different distances.



Visual Acuity - what does it mean?

Visual acuity is the term used to describe the smallest detail a person can see when looking straight at a stationary, high contrast (e.g. black on white) target in good lighting. Please follow this link or click on the icon above to learn more.


How is Visual Acuity measured

Visual acuity is measured in different ways depending on the age and abilities of the patient. Please follow this link or click on the icon above to learn more.


How is Visual Acuity Recorded?

Visual acuity is usually recorded as a Snellen fraction such as 6/60 (UK) or 20/200 (US). Please follow this link or click on the icon above to learn more.


Resolution Visual Acuity

Acuity can be estimated from infants and those with communication difficulties using special techniques. Please follow this link or click on the icon above to learn more.


Recognition Visual Acuity

If patients are able to name or match pictures or letters we can measure recognition acuity. Please follow this link or click on the icon above to learn more.


Printable examples

If you have a recorded visual acuity (e.g. 6/60 or 20/200) these web pages should allow you to obtain a printout of the size of images that should be seen easily at different distances. Please follow this link or click on the icon above to learn more.


Accuracy of Downloading Images

Check for distortion in downloading these images. Please follow this link or click on the icon above.


Snellen Fraction Conversions

Other ways of recording acuity e.g. cycles per degree and LogMAR may be converted to Snellen fractions. Please follow this link or click on the icon above to learn more.


Acknowledgements

These web pages were designed by Barry Johnston, Dr. Kathryn J. Saunders and Dr Julie-Anne Little with the advice and support of many others. The work has been supported by the R&D Office, Northern Ireland (Epidemiology RRG 4.4, Knowledge Transfer Grant RES/4214/09) and the University of Ulster Vision Sciences Research Group. Please follow this link or click on the icon above for full details.