orthok

Orthok, often written Ortho-K and short for orthokeratology, is a non-surgical vision correction method that uses specially designed rigid gas-permeable contact lenses worn overnight to temporarily reshape the cornea. By gently flattening the central cornea, the lenses alter the eye’s focusing power so that, during the day, clear vision is possible without glasses or daytime contact lenses. It is commonly used to correct mild to moderate myopia and, to a lesser extent, astigmatism, and it is popular among children and adults seeking a non-surgical correction or myopia control.

The process begins with a comprehensive eye examination and corneal topography to design a customized lens. Patients wear the lenses overnight; during the day, vision is typically clear as long as the lenses are worn overnight as prescribed. Results are reversible, and maintenance requires ongoing lens wear and periodic checkups.

Safety and effectiveness vary by individual. Benefits include independence from daytime correction and the potential to slow myopic progression in children. Risks include corneal irritation, infections, and rarely corneal ulcers or staining, particularly with inadequate lens care.

Suitable candidates generally include those without active eye disease, keratoconus, or significant dry eye; contraindications include active infection or very irregular corneas.

Orthokeratology traces back to mid-20th century rigid lens practice and gained momentum in the 1990s with modern gas-permeable materials. It remains a non-surgical option for vision correction and myopia management.

See also: Orthokeratology, Myopia control, Contact lens.