Ortho-K and Invisalens
How Ortho-K Works
An Ortho-K lens uses a reverse geometry design. Its centre is flatter than the cornea and a steeper zone behind it creates gentle hydraulic forces in the tear film, redistributing surface corneal cells from the centre towards the mid periphery overnight.
In short
Tear film pressure, not weight, moves surface cells outward. The effect lasts about a day.
The common assumption is that the lens presses the cornea flat like a weight. It does not. The mechanism is hydraulic, and it happens in the microscopically thin layer of tears between the lens and the eye.
A conventional rigid lens is shaped roughly like the cornea, steepest in the centre. An Ortho-K lens is built the opposite way around. Its central zone is deliberately flatter than your cornea, and immediately outside it sits a steeper reverse curve. That geometry creates a positive pressure under the centre of the lens and a negative pressure under the reverse curve.
Overnight, those opposing forces move cells in the epithelium, the outermost corneal layer, out of the centre and into the ring around it. The centre thins slightly, the mid periphery thickens slightly, and the overall curve flattens by a calculated amount. No deeper corneal layer is touched, which is why the whole thing reverses.
The epithelium naturally replaces itself over days, and that turnover is what limits how long the effect holds. It is also why the correction is so consistent from night to night once the design is right.
What to expect
- Fluorescein assessment
- A harmless orange dye shows the tear layer under a cobalt blue light, making the fit pattern directly visible rather than inferred.
- Repeat topography
- Maps taken before treatment and after the first nights are compared directly, so the change achieved is measured rather than estimated.
What is included
- Reverse geometry lens design generated from your own corneal map
- Fluorescein fit assessment at the slit lamp
- Before and after topography comparison
- Design refinement across the settling period
What this does not do
- Corneal response varies between individuals, so the first design is rarely the final one.
- Very irregular corneas do not respond predictably to this mechanism.
Questions and answers
Does the lens damage the cornea?
The reshaping affects only the epithelium, the surface layer that continuously renews itself. Deeper corneal layers are not altered. Corneal health is checked at every follow up precisely so any surface change is caught early.
Why does it wear off during the day?
The epithelium is elastic and constantly renewing, so it gradually returns towards its natural profile. Most wearers hold good vision through a full waking day and some notice slight softening late in the evening.
Why does it take a week or two to stabilise?
Cell redistribution is progressive. The first night moves a significant portion of the correction, and each subsequent night refines it until the profile reaches equilibrium.
Talk to someone about how ortho-k works
Appointments are scheduled two per hour, so there is time to answer questions properly. Call (480) 706-3937 or request a time online.