Orto-K

Also known as corneal reshaping, night lenses, ortho-K, OK, Overnight Vision Correction, Corneal Refractive Therapy, CRT, accelerated orthokeretology

thumb|right|Orthokeratology lens Orthokeratology, also referred to as Night lenses, Ortho-K, OK, Overnight Vision Correction, Corneal Refractive Therapy (CRT), Accelerated Orthokeretology, Cornea Corrective Contacts, Eccentricity Zero Molding, and Gentle Vision Shaping System (GVSS), is the use of gas-permeable contact lenses that temporarily reshape the cornea to reduce refractive errors such as myopia, hyperopia, and astigmatism.