Have you ever wondered how wearing contact lenses while sleeping can help you see clearly the next morning?
That's the fascinating idea behind Orthokeratology (Ortho-K), a non-surgical vision correction method that uses specially designed contact lenses to temporarily reshape the cornea overnight.
But how can something so small make a difference to your vision? And what actually happens during an Ortho-K fitting?
Let's take a closer look.
Your Cornea Is Only Half a Millimetre Thick
The cornea is the clear, curved surface at the front of your eye. Although its central thickness is only about 0.5 millimetre, itprovides much of the eye's focusing power.
When you have myopia (short-sightedness), light focuses in front of the retina instead of directly on it, making distant objects appear blurry.
Ortho-K works by making tiny, temporary changes to the cornea's curvature, helping light focus more accurately on the retina.
Interesting fact: Even a small change in the cornea's shape can noticeably affect how clearly you see. That's why precise measurements are so important during an Ortho-K fitting.
What Actually Happens While You Sleep?
Ortho-K lenses are specially designed, oxygen-permeable rigid contact lenses worn overnight and removed in the morning.
As you sleep, the lenses interact with the thin tear layer between the lens and your eye, gently redistributing cells in the cornea's outermost layer.
This temporarily flattens the central cornea in people with myopia, changing how light enters the eye.
When the lenses are removed in the morning, the reshaped cornea may allow clearer vision throughout the day without glasses or daytime contact lenses.
Some people notice an improvement after the first night, while others need several nights or longer for their vision to become stable.
Did you know? Ortho-K does not permanently change your cornea. If you stop wearing the lenses, your cornea gradually returns towards its original shape, and the vision correction effect wears off.
Inside an Ortho-K Fitting: What Does Your Optometrist Check?
An Ortho-K fitting involves more than choosing a contact lens based on your spectacle prescription.
Because every cornea has a unique shape, your optometrist needs to assess several factors before selecting a suitable lens design.
1. Eye Examination
Your optometrist begins by checking your prescription, vision and overall eye health.
The examination helps determine whether your eyes are suitable for Ortho-K and whether any conditions require attention before starting.
2. Corneal Mapping
One of the most interesting parts of an Ortho-K fitting is corneal topography.
This specialised instrument creates a detailed, colour-coded map of the cornea, showing its curvature and shape.
Think of it like a landscape map, except instead of hills and valleys, it reveals the subtle curves of your eye.
Fun fact: Two people can have the same spectacle prescription but different corneal shapes. That's why Ortho-K lenses need to be selected and fitted according to each person's eyes.
3. Lens Fitting and Assessment
Using the measurements collected, your optometrist selects an appropriate Ortho-K lens design and assesses how it sits on your eye.
The lens position, movement and fitting pattern are checked carefully. Adjustments may be needed to achieve a suitable fit.
You will also learn how to insert, remove and care for your lenses before starting overnight wear.
4. Your First Morning Check
After your first night of Ortho-K wear, your optometrist will usually arrange an early follow-up.
Your vision, corneal shape and eye health are reassessed to see how your eyes have responded overnight.
Further appointments help monitor the results and ensurethat the lenses continue to fit appropriately.
Can Ortho-K Help Children With Myopia?
Besides providing clearer daytime vision, Ortho-K is also used as a myopia control option for suitable children.
Research suggests that Ortho-K can help slow myopia progression by reducing the rate at which the eye elongates.
For parents in Singapore concerned about their child's increasing short-sightedness, Ortho-K may be worth exploring.
However, suitability depends on the child's prescription, corneal shape, eye health and ability to follow proper lens hygiene routines.
Is Overnight Ortho-K Wear Safe?
Ortho-K lenses are specifically designed for overnight wear, but they are not without risks.
As with other contact lenses worn during sleep, eye infections and other complications can occur.
Professional fitting, proper cleaning and handling, and regular follow-up appointments are essential to help reduce these risks.
If you experience eye pain, redness, unusual light sensitivity or sudden blurred vision, remove the lenses and seek prompt eyecare.
Discover the Science Behind Clearer Daytime Vision
From a cornea only about half a millimetre thick to detailed eye mapping and carefully fitted overnight lenses, Ortho-K shows how small changes to the eye's surface can influence vision.
For children with progressing myopia or individuals interested in daytime vision without spectacles, understanding the fitting process is an important first step.
Curious about whether Ortho-K is suitable for you or your child?
Visit People's Optics at Yishun or Tampines, Singapore, for a professional Ortho-K assessment. Our optometrists can evaluate your eyes, explain how Ortho-K works and help you explore suitable vision correction and myopia management options.
