Ortho-K (orthokeratology) is a vision correction method that uses specially designed rigid contact lenses worn overnight to temporarily reshape your cornea while you sleep. You remove the lenses in the morning and see clearly throughout the day without glasses or daytime contacts. The effect is reversible: if you stop wearing the lenses, your cornea gradually returns to its original shape and your vision goes back to what it was before.
How the Lenses Reshape Your Cornea
Ortho-K lenses look similar to standard hard contact lenses, but their back surface has a reverse geometry, meaning the curve is deliberately opposite to your cornea’s natural shape. When you close your eyes and the lens sits against your cornea overnight, it applies gentle, targeted pressure that redistributes the thin outermost layer of the cornea (the epithelium). This flattens the central cornea just enough to change how light focuses on your retina.
The reshaping is remarkably shallow. Studies confirm that the changes are confined almost entirely to the epithelial layer, with no bending of the deeper corneal tissue and no change to the internal structures of the eye. The overall corneal thickness thins slightly in the center, while the mid-peripheral zone thickens a small amount. That redistribution is what corrects your focus.
What It Corrects
Ortho-K works best for mild to moderate nearsightedness (myopia), typically up to about -6.00 diopters, with astigmatism of 1.50 diopters or less. People with higher prescriptions or significant astigmatism generally aren’t good candidates because the lens can’t safely redistribute enough tissue to fully correct the error. If your prescription falls within that range and your corneas are healthy, you’re likely a candidate.
The lenses are not designed for farsightedness, and certain eye surface conditions, such as chronic lid margin disorders, misdirected lashes, or sensitivity to rigid lens care products, can make ortho-K a poor fit.
Slowing Myopia in Children
Beyond correcting existing nearsightedness, ortho-K has become one of the most studied tools for slowing myopia progression in children. This matters because childhood myopia tends to worsen year after year, and higher levels of myopia later in life carry increased risk of serious eye conditions like retinal detachment and glaucoma.
The evidence is strong. The ROMIO randomized trial found that ortho-K reduced the rate of eye elongation (the physical change that drives worsening myopia) by 43% compared to standard glasses. A large meta-analysis pooling multiple studies found a 45% reduction on average. Some recent retrospective data has shown even larger effects: one study measured a 55% reduction in progression rate across 90 eyes, and a subgroup of patients whose corneas responded particularly well to flattening showed a 94% reduction. Results vary by child, but the consistent finding across studies is that ortho-K meaningfully slows the worsening of nearsightedness during the critical growth years.
What the First Weeks Look Like
After your first night wearing ortho-K lenses, you’ll notice some improvement in your vision, though it won’t be dramatic. Over the next several days, clarity improves as your cornea gradually holds its new shape for longer periods. Most people reach stable, full-day vision within one to two weeks of consistent overnight wear.
During that initial adjustment, you may need backup glasses for part of the day, especially in the late afternoon or evening as the reshaping effect begins to fade. Once your cornea has adapted, the correction typically lasts through a full waking day. You do need to wear the lenses every night (or in some cases every other night, depending on your prescription) to maintain the effect. Skip a few nights and your vision gradually reverts.
The Nightly Routine
Ortho-K lenses require careful handling because they’re worn during sleep, when the eye is more vulnerable to infection. The basic routine involves washing your hands thoroughly with antibacterial soap, drying them with a lint-free towel, and cleaning the lenses with the specific solutions your eye care provider recommends before insertion. In the morning, you remove the lenses, clean them again, and store them in fresh disinfecting solution.
A weekly or biweekly protein-removal soak helps maintain the lens surface. The lenses sit in an intensive cleaner for about 30 minutes, then get rinsed with saline before the next use. Swapping in different solutions or skipping steps to save time increases infection risk, so consistency matters. One practical tip: avoid handling lenses in the bathroom, which tends to harbor more bacteria than other rooms.
Safety and Infection Risk
The primary safety concern with any overnight lens wear is microbial keratitis, a corneal infection that can threaten vision if not treated quickly. A large multicenter study found the incidence among ortho-K wearers was 5.4 cases per 10,000 patient-years. That rate is comparable to what’s seen with daily-wear soft contact lenses, which is reassuring given that sleeping in any contact lens generally raises infection risk.
Milder surface staining of the cornea is relatively common, especially in people with pre-existing eyelid issues or solution sensitivities, but it’s usually managed by adjusting the lens fit or switching care products. The key risk factors for serious problems are the same as with any contact lens: poor cleaning habits, skipping disinfection steps, and not replacing lenses on schedule.
How It Compares to LASIK
Ortho-K and LASIK both reshape the cornea to correct nearsightedness, but they differ in almost every practical way. LASIK is a one-time surgical procedure that permanently removes corneal tissue, while ortho-K is temporary and fully reversible. LASIK requires stable vision and is generally performed on adults (typically 18 or older), whereas ortho-K can be started in childhood, which is precisely why it’s used for myopia control.
In terms of visual quality, LASIK has a slight edge. A comparison study found no difference between the two during daytime conditions with normal pupil size, but in dim lighting when pupils dilate, LASIK provided better contrast sensitivity and sharper vision, particularly for moderate prescriptions. For someone whose myopia is stable and who wants a permanent fix, LASIK delivers better optical performance. For children, for people who aren’t surgical candidates, or for anyone who prefers a reversible option, ortho-K fills a role that LASIK can’t.
Cost and Ongoing Expenses
The initial cost of ortho-K, including the eye exam, custom-fitted lenses, and early follow-up visits, ranges from about $1,000 to $4,000 depending on the complexity of your prescription. Lower prescriptions fall toward the bottom of that range, while higher corrections push the price up.
After the first year, annual costs drop to roughly $650, which covers a follow-up exam, updated corneal mapping, and replacement lenses. If you need extra lenses outside that cycle, they run about $150 per lens. Most vision insurance plans don’t cover ortho-K, though some flexible spending or health savings accounts can be used. Over several years the cumulative cost is higher than glasses but comparable to premium daily disposable contacts, and for children getting the myopia-control benefit, many families consider it a worthwhile investment against stronger prescriptions down the road.
Lens Materials and Oxygen Flow
Because ortho-K lenses are worn with eyes closed for hours, they need to allow enough oxygen through to keep the cornea healthy overnight. Modern ortho-K lenses are made from highly gas-permeable materials with oxygen permeability (Dk) values ranging from about 100 to 127. For context, higher Dk means more oxygen reaches the cornea. The two most common lens designs, CRT and VST, use slightly different materials and geometries, but both meet the oxygen demands of overnight wear. Your practitioner will choose a design based on your corneal shape, prescription, and how your eye responds during the fitting process.