A contact lens (also known simply as a contact) is a corrective, cosmetic, or therapeutic lens usually placed on the cornea of the eye. Contact lenses usually serve the same corrective purpose as glasses, but are lightweight and virtually invisible. Many commercial lenses are tinted a faint blue to make them more visible when immersed in cleaning and storage solutions. Some cosmetic lenses are deliberately colored to alter the appearance of the eye. Lenses now have a slight bluish tint which is a thin UV coating; this reduces glare and cornea damage much like a pair of sunglasses.
Orthokeratology is the reduction, modification or elimination of a refractive error by the programmed application of contact lenses. Basically you wear a contact lens overnight which gently moulds your cornea, reducing your prescription. In most cases this means that you can perform normal functions without glasses.
This method can be used as an alternative to glasses, refractive surgery, or for those who prefer not to wear contact lenses during the day. The latter may be due to discomfort from working in air-conditioned or dusty
environments, from extended computer usage which reduces blink rates and tear film production or from displacement or loss during sports activities.
Rigid Gas Permeable (RGP) contacts are a harder, high-tech alternative to the traditional soft contact lenses (not to be confused with the older, more rigid type of contacts, which are now essentially obsolete).
Using modern technology, these contacts are tailored to you by using the topography of your eye, and use thinner materials and with smoother edges than was traditionally possible, because these sort of contacts allow oxygen to pass through—which all adds up to the contact being more comfortable to wear, over time, than the older types.
It is worth noting, however, that wearing this type of contact does require a period of time to get used to the sensation. For that reason, they’re most recommended for patients where they will be used regularly, so that the eye doesn’t ‘lose’ its comfort with them.