Chromagen lenses are a series of coloured filters initially created to help with colour blindness and then further developed to treat dyslexia and specific learning difficulties. The lenses can be worn as soft contact lenses or as spectacles and may treat one or both eyes depending on symptoms. The prescription is based on a series of tests which usually take around 3 hours – including time in the consulting room and time trialing the filters. However, this doesn’t have to take place in one go but can be spread over a number of visits to match the patient’s needs. This is particularly important for children – we like to work at the right pace for the child and the parent.