Some minimum visual standards that you must fulfil in order to qualify. You should have a minimum corrected vision of at least 6 / 12 in each eye. You could also have 6 / 6 in the healthier eye and 6 / 18 in weaker eye with spectacles with power not more than + / -5.50 Dioptres, inclusive of astigmatism in any meridian with full field of vision and Minimum CP-IV unsafe colour vision. There are, however, other detailed visual and colour standards that are specific to different trades.