Orthokeratology, or Ortho-K, is a non-surgical vision correction method. It involves wearing specially designed contact lenses, typically overnight, to reshape the front surface of the eye. The goal is to provide clear vision throughout the day without glasses or standard contact lenses. It is used for various refractive errors, including nearsightedness (myopia) and astigmatism.
The Science Behind Ortho-K
Ortho-K lenses are rigid gas permeable (RGP) lenses specifically engineered to gently and temporarily reshape the cornea, the clear, dome-shaped outer layer of the eye. While worn during sleep, these lenses exert a subtle pressure on the tear film beneath them, which then redistributes cells in the outermost layer of the cornea, known as the epithelium. This cellular redistribution causes the central cornea to flatten slightly and the peripheral cornea to thicken.
This temporary change in corneal curvature alters how light enters the eye, allowing it to focus directly on the retina, thus correcting refractive errors like myopia. In myopia, the cornea is typically too curved, causing light to focus in front of the retina. By flattening the central cornea, Ortho-K lenses adjust this focus, enabling clear distance vision. The effect is entirely temporary and reversible; if lens wear is discontinued, the cornea gradually returns to its original shape, and the refractive error will reappear.
Ortho-K can also address astigmatism by creating a more spherical corneal surface, which ensures light focuses uniformly on the retina. Beyond vision correction, Ortho-K has shown promise in managing myopia progression, particularly in children. By reshaping the cornea to bring peripheral light rays into focus on the retina, Ortho-K may help slow the elongation of the eyeball, a primary factor in myopia progression. This makes it a significant tool for long-term eye health in younger individuals.
Who Is a Candidate
Ortho-K is primarily suited for individuals with mild to moderate nearsightedness, typically up to -6.00 diopters, and astigmatism, often up to -1.75 diopters, though some designs can correct higher levels. It is also effective for those with mild farsightedness.
Ortho-K is frequently recommended for children and teenagers because their eyes are still developing and respond well to the reshaping process. It provides an alternative for vision correction, especially for those too young for laser eye surgery like LASIK, which typically requires stable vision.
Adults can also be good candidates, particularly those who prefer not to wear glasses or contact lenses during the day due to active lifestyles, sports, or certain occupations. Overall eye health is a prerequisite, and a comprehensive eye examination is necessary to assess the thickness, curvature, and general condition of the cornea to determine suitability.
The Ortho-K Treatment Process
The Ortho-K journey begins with a thorough eye examination and consultation with an eye care professional specializing in the treatment. During this initial assessment, the practitioner will meticulously measure and map the surface of the cornea using a specialized instrument called a corneal topographer. This detailed mapping is crucial for designing custom lenses that precisely fit the unique curvature of each eye.
Once the custom lenses are fabricated, the patient receives them along with comprehensive instructions on proper lens application, removal, and hygiene. The lenses are worn overnight, typically for 6 to 8 hours, while the individual sleeps. Most people begin to experience improved vision within the first few days, with significant correction often achieved within one to two weeks, depending on the initial prescription.
Regular follow-up appointments are an integral part of the Ortho-K process. These visits allow the eye care professional to monitor the progress of corneal reshaping, make any necessary adjustments to the lens fit, and ensure the eyes remain healthy. As the cornea stabilizes into the desired shape, the frequency of lens wear may be adjusted; some individuals may eventually wear their lenses every other night or on a less frequent schedule to maintain clear vision.
Safety and Important Considerations
Ortho-K is generally considered safe when prescribed and monitored by an experienced eye care professional. However, like all contact lens wear, there are potential risks, with the most significant being eye infections. Although rare, serious infections like microbial keratitis can occur, emphasizing the importance of strict hygiene practices.
To minimize risks, meticulous lens care, including proper cleaning and storage, is important. Regular follow-up appointments with the eye care provider are also important to detect and address any potential complications early.
Some individuals may experience mild discomfort, irritation, or temporary vision fluctuations, such as glare or halos, particularly during the initial adaptation period, though these usually subside as the eyes adjust.
Consistent overnight lens wear is necessary to maintain the desired vision. While Ortho-K lenses are designed to be highly oxygen-permeable for eye health during overnight wear, maintaining good ocular hygiene and adhering to professional guidance remains important for a safe and successful outcome.