Your Quick Guide to Corneal Refractive Therapy
If you have eye conditions or refractive errors like near-sightedness but you don’t want to wear eyeglasses or soft contact lenses because of your personal preference or occupation then there are options to consider like corneal refractive therapy.
This treatment allows you to correct your vision without having to constantly wear glasses or contact lenses during the day. Let’s take a closer look at corneal refractive therapy (CRT) starting with a definition of the treatment.
What is Corneal Refractive Therapy?
Corneal refractive therapy (or orthokeratology) is a non-surgical treatment that uses specially designed contact lenses (rigid gas permeable or RGP contact lenses) to reshape the cornea at night while you are sleeping. The night-time corneal reshaping allows for clear daytime vision without the need for eyeglasses or contacts during the day¹.
What are CRT Lenses?
CRT lenses (Corneal Refractive Therapy lenses) are specialized gas-permeable contact lenses designed to reshape the cornea overnight to temporarily correct vision, primarily for people with myopia (nearsightedness). Manufactured by Paragon Vision Sciences, CRT lenses are part of a broader category known as orthokeratology (Ortho-K) lenses, but they are a specific brand with their own design and methodology.
What are Ortho-k Lenses?
In simple terms, CRT or Ortho-k lenses are specially designed lenses used to administer corneal refractive therapy. While they follow the same general idea as CRT lenses, Ortho-K lenses refer more generally to any corneal reshaping lenses, which may include CRT and other types from different manufacturers.
How Do CRT and Ortho-k Lenses Work?
CRT lenses work by gently reshaping the cornea as you sleep. They are worn overnight to apply gentle pressure to specific parts of the cornea, gradually reshaping and flattening certain areas.
During the day, the cornea maintains its new shape allowing clear vision without the need to wear glasses or contacts. By reshaping the cornea, ortho-k lenses slow the progression of myopia. While the effect can last long during the day, CRT lenses must be worn consistently every night, or they won’t allow clear vision the next morning.
Types of Corneal Refractive Therapy
The treatment can be classified based on the type of CRT lens used. In this regard, there are two main types:
- Rigid gas permeable or RGP lenses
- Hybrid lenses
1) Rigid Gas Permeable lenses or RGP Lenses
These types of specialized lenses are made from breathable materials capable of reshaping the cornea overnight. RGP lenses are designed to flatten specific parts of the cornea (more so, the centre part of the cornea) reducing and eventually correcting refractive errors like near-sightedness or astigmatism.
2) Hybrid Lenses
Corneal refractive therapy can also utilize hybrid lenses that combine the rigid centre of an RGP lens and a softer outer skirt to improve comfort.
How Long Do You Have to Wear Ortho-K Lenses?
Ortho-k lenses should be worn nightly for 6 to 8 hours to maintain vision correction, as the corneal reshaping effect is temporary. If you stop wearing them every night (while sleeping), your cornea will return to its original shape gradually within a day or two. Some individuals may wear them every other night depending on their vision needs and how their eyes respond.
How Long Does It Take for Ortho-K to Work?
Ortho-k lenses can begin to work as soon as after the first night of use, but the time it takes to achieve full vision correction depends on the severity of your myopia or other refractive errors. For those with low myopia (less than -2.00D), a noticeable improvement can happen within 3 to 4 days. For medium myopia (-2.00 to -4.00D), it typically takes about 1 week to see significant results, and for those with higher levels of myopia (over -6.00D), it can take between 2 to 3 weeks to reach optimal correction².
Is Ortho-k Permanent?
No! You should be able to have improved vision 24-72 hours after getting ortho-k lenses. Generally, it will take 14 days or more to get maximum vision correction from ortho-k lenses although some people experience significant improvement in a few days of treatment³. This is the case if you use them as prescribed.
How Long Do Ortho-k Lenses Last?
The lenses can last from months to a year or two depending on several factors such as the quality of the lens material. High-quality ortho-k lenses made using durable materials will last longer. Lens care and maintenance also matter. If you clean and store your lenses as directed, they will serve you longer and better.
Other individual factors like eye health, lifestyle, and how well a patient’s eyes adapt will also dictate longevity. For the most accurate estimate of the longevity of your ortho-K lenses, consult with our Ortho-K eye doctors. Regular visits are also critical as this is when a patient’s condition is assessed, and a decision is made on whether they need to have their ortho-k lenses replaced or further customized.
How To Wear Ortho-k Lenses
Once you have your custom ortho-k lenses made to fit your eyes and correct your underlying vision condition, it’s time for the contact lens fitting process. Here’s a simple guide to follow.
Step 1: Clean Your Hands
Ortho-K lenses are generally worn at night before going to bed. Before handling the lenses, ensure you clean your hands properly using soap and water.
Step 2: Prepare Your Ortho-k Lenses
After cleaning your hands, remove the lenses from the case, rinse them with the contact lens solution provided, and place one of the lenses on your finger (preferably index finger).
Step 3: Inserting the Lenses and Sleep
Look up, open your eye wide, and place the lens on the cornea aiming at the centre. Blink gently to settle the lens and repeat the process for the other eye. Avoid rubbing/touching your eyes. Wear the lenses overnight as you sleep.
Step 4: Removing the Lenses in the Morning
Remove the lenses in the morning. Before doing so, ensure your hands are clean. Remove individual lenses by tightening your eyelids to dislodge the lens on your eye or use a RGP lens plunger. Rinse the contacts using your contact lens solution and store them in your contact lens case. For full removal techniques, please ask us to learn more.
Important: The above steps are overgeneralized. There are other steps, tips, and recommendations to consider based on a person’s individual needs. Ask an eye care professional for further information and assistance.
For this reason, consider booking a corneal refractive therapy consultation with our optometrists at Kodak Lens Vision Centres to get more conclusive information on wearing overnight Ortho-k lenses and more!
CRT vs. Ortho-k: What’s the Difference?
CRT is a specific type of ortho-k that uses Paragon CRT lenses, whereas ortho-k refers to the general practice of corneal reshaping using overnight lenses from various manufacturers. Both are effective at temporarily correcting vision by reshaping the cornea during sleep.
Visit Kodak Lens Vision Centres – Get Safe and Effective Corneal Refractive Therapy in Toronto & the Greater Toronto Area
Book an appointment with any of the trusted optometrists at Kodak Lens Vision Centres at our seven locations. Find out more about contact lens corneal reshaping here.
Kodak Lens Vision Centres have experienced optometrists, and the corneal mapping technology required to understand a patient’s precise corneal shape and other important details such as the curvature, using detailed 3D mapping.
Our process is also simple, quick, and comfortable. Our mapping tool won’t touch your eyes, and we’ll collect all the information needed to design custom perfectly fitting ortho-k lenses.
Book an appointment now. Discover other forms of myopia control and vision correction solutions like myopia control spectacle lenses (STELLEST or MiYOSMART) and low-dose atropine eye drops.
Call: 647-492-1641 for corneal refractive therapy for children and teenagers among other services including comprehensive eye exams that detect existing eye diseases. Also, discover the professional service fees for orthokeratology. Enjoy optimum vision without glasses, contacts or laser vision correction surgery!