These contact lenses use a principle known as Orthokeratology, or Ortho-K. The lenses are worn overnight to gently reshape the surface of the front of the eye (cornea), consequently reducing the progression of myopia. They can then be removed in the morning to give crisp, natural vision all day.
This has the advantage of not needing to wear lenses during the day, which can be especially useful for those in active sports, particularly contact and water sports. It also means that parents don’t have to worry about their children wearing CLs during the day when they are away from home and results in a reduced risk of hygiene lapses when away from parental supervision.