It is possible to have a serious vision problem and not be aware of it. Vision problems that are left undetected and untreated may lead to vision loss and in some cases blindness. Early detection is the key to minimizing vision loss.

A good and effective way to test your vision for problems accurately is with a vision test, known as your visual acuity. It is one of the simplest, yet most important components of the eye examination. It can be determined by testing how clearly you are able to see text from a standard distance. This is done with a 'Snellen' chart, named after its inventor, Herman Snellen, a Dutch ophthalmologist who worked at the turn of the 19th century. The Snellen chart typically features eleven rows of letters, which are largest on the top row and smallest on the final row.

Measuring visual acuity is recorded by recognising the lowest row of letters on the chart. It does not matter if a person is unable to read the letters, as shapes or symbols can also be used. This enables people of all ages and reading ability to opportunity to complete the test with ease; including young children. Best practice is to ask the patient which symbols/letters they find easiest to identify.

Each line of the chart is assigned two numbers in the form of a fraction that represents a person's visual acuity. The first number, or numerator, is the distance in metres you are away from the eye chart (6 in metric measurements) The second number, or denominator, represents the distance in metres an eye with 'normal' vision can read the same line. For example, if you can read 6/40 you are able to see what a normal eye can see at 40 metres. (20/20 vision refers to 20 feet, in metric measurements this converts to 6 metres).

If you are a patient at the Launceston Eye Institute you will have your visual acuity tested at each visit by the ophthalmic technicians; prior to your appointment with the ophthalmologist. This is to obtain a base line of your vision enabling your ophthalmologist the ability to monitor the natural progression of your vision and observe any irregular changes.


Thistle Street Medical Centre
Level 1, 36 Thistle Street West
South Launceston, TAS 7249

4 Eastland Drive
Ulverstone, TAS 7310

phone 03 6344 1377
fax 03 6344 1577

©2015 Launceston Eye Institute