Orthokeratology

Orthokeratology, or Ortho-K, lens is a hard gas-permeable contact lens specially designed to be worn overnight and removed in the next morning. It works by flattening the center of the cornea, changing how light is bent as it focuses on the retina. When you wake up and take out the lenses, you should be able to see clearly throughout a certain period of time during the day without wearing glasses or other contact lenses. These overnight lenses are gas-permeable, and hard enough to reshape the cornea, and also allow oxygen to pass through so your eyes stay healthy.