If you need glasses to read a number plate at 20.5 metres - that is fine
If you need glasses or contact lens to read the number plate, that is fine, however, you must wear them during the test and whenever you drive. If you have had sight correction surgery you should declare this when you apply for your provisional licence.
You must satisfy the examiner that in good daylight you can read a vehicle number plate with letters 79.4mm (3.1in) high at a minimum distance of 20.5 metres (about 67 feet). Number plates with a narrower font, such as the new style number plates introduced during 2001, should be read from a distance of 20 metres (66 feet).
Before you get into your car your examiner will point out a vehicle and ask you to read the number plate. If you can't speak English or have difficulty reading, you may copy down what you see. If your answer is incorrect, your examiner will measure the exact distance and repeat the test. If you fail the eyesight test If you can't show your examiner that your eyesight is up to the required standard - you will have failed your driving test - your test will go no further.