What is OOK?
Optimal Orthokeratology (OOK) is a vision correction therapy for patients with moderate myopia (nearsightedness) and low amounts of astigmatism. A retainer, worn at night, manipulates the fluid forces of the tear layer in your eye to reshape your eye's outer surface. (By tear layer, we mean, of course, the layer of clear salty lubricating liquid in your eye, the same liquid that is in tear drops when one cries.) A "contact lens" retainer while you sleep
Modern Optimal Orthokeratology (OOK) is a vision correction therapy for patients with moderate myopia (nearsightedness) and low amounts of astigmatism. It involves wearing a contact lens retainer while you sleep to gently and painlessly reshape the surface of your eye.
By controlling the shape change of your epithelium (outer layer of your cornea) we alter the refractive power of your eye to correct the error in your vision. While you sleep, the tiny forces applied by your tears squeezed between your retainer and cornea apply the necessary tension to reshape the surface of your eye. The OOK retainer never actually touches the cornea; it sits on a layer of your natural tears. In addition, the forces applied to your epithelium are so minute, it is impossible to feel or sense the effect of the lenses on your eye. But you will see
the effects of the therapy when you remove the OOK retainer in the morning. Your myopia has been corrected and you enjoy your day without glasses or contacts! Its reversible and non-surgical
The reversible nature and long term effects of OOK therapy can be understood by comparing it to wearing a ring on your finger. When you remove a ring, the skin has been moulded. The longer you wear that ring, the longer it takes for the skin to return to its normal shape. OOK therapy affects the cornea in a similar nature. After a month of nightly wear, your eye will have an increased retention of the correcting effect.
In other words, the cornea holds its altered shape for a longer period. This reduces the number of nights that you are required to wear your retainers. After a year of therapy, many patients wear their OOK retainers only 1 or 2 nights per week! Wearing OOK retainers only a limited number of times per week, and only while asleep, makes the therapy very attractive to patients looking for an alternative to glasses and conventional contact lenses.
The therapy also provides you with the piece of mind that its effect is reversible should you choose to discontinue wearing your OOK retainers. Because it is non-surgical, you can return to your pre-therapy vision and corneal shape by simply not wearing your OOK lenses.
Optimal Orthokeratology offers many distinct and unique benefits. But clearly, the reasons to choose OOK therapy is for the freedom it offers you from glasses & daily contacts and the sharp vision that results. How does it Work?
While sleeping, an OOK retainer, via fluid pressure, gently reshapes the "lens" of your eye improving its focussing power. When you waken and remove the retainer your eye retains this improved shape throughout the day, delivering natural unassisted 20/20 vision. You can reverse the effects by ceasing to wear the retainer, and your eye will gradually return to its natural shape. What is wrong with my vision?
A nearsighted (myopic) patient has little difficulty with near vision but a reduced ability to see in the distance. If light rays entering the eye (through the cornea) are incorrectly focused on the retina then a patient will have blurred vision (worse than 20/20).
Imagine the retina as a movie screen, and the cornea as the lens of a projector and everything that we see as the light source. If the lens of the projector is not accurately focused, the image on the screen is blurred. However, if we change the focusing power of the projector lens, we can improve the quality of the image on the screen. OOK fixes the problem
Optimal Orthokeratology improves the focusing power of the lens. By changing the refractive power of the eye, we can accurately focus light rays on the retina providing crisp, clear vision. In fact, very small shape changes in the cornea can improve a patients' vision dramatically.
The part of the cornea most affected by OOK is the epithelium or outer "skin" of the eye. The epithelium is made up of layers of cells which behave in a very fluid-like nature. In fact, the epithelium is 400 times more sensitive to pressure than the surface below (the stroma). OOK manipulates the fluid nature of the epithelium to change the focusing power of the eye. By "pulling" central cells towards the periphery of the cornea, a "flattening" effect is created which improves the patients' ability to see in the distance. What exactly happens?
Moving cells is easily understood. You can press your thumb into your leg and see the skin move. If you hold your thumb there long enough, you will see the impression in your skin. The magic of OOK is controlling the shifting of epithelial cells to achieve the required refractive change.
The inventors of the OOK lens, two optometrists in Australia, have studied and researched the eye and the forces required to change its shape. Through a great deal of study and the assistance of many experts in a variety of fields, they have determined a formula and solution to accurately control epithelial movement. By creating a specific fluid contour between your OOK retainer and the cornea, tiny forces are produced. The higher the prescription, the more the epithelium needs to change shape and therefore the stronger the fluid forces need to be. You do not need to understand these tear forces and you won't be able to feel them. However, your Optimal Orthokeratologist understands how to manipulate them to achieve the desired result. What is important for you to know is that OOK therapy does not compress, damage, destroy or permanently alter your cornea. In fact, the retainer never even touches your eye. The OOK retainer rides on a layer of your tears and applies minute forces to the cells of your epithelium. The forces shift your cells temporarily, correcting the focusing error of your cornea, for only as long as you continue OOK therapy.
After the first night of wear, we expect 70% of the epithelial shifting which means that your vision will be greatly improved after only one night of sleep! Throughout the day, you may notice a reduction in the quality of your vision, which we call "regression", as your epithelium, without the retainer in place, shifts back to its normal uncorrected shape. After a week of sleeping in your OOK lenses, 100% of the change should be evident by your crisp, sharp vision. In addition, the retention throughout the day and evening should be far improved. After a month, you may be able to skip wearing the retainer one or two nights a week. In other words, the longer you continue the therapy, the better the retention of the effect becomes. That is, your epithelial cells are slower to shift back to their normal shape. After one year, we are hope to have you wearing your OOK retainer only 1 or 2 nights a week! Benefits of OOK
Laser (PRK) or LASIK surgery achieves the refractive results in a similar fashion to OOK. During surgery, the laser oblates (burns) the cells of the cornea away to achieve the correct corneal shape. OOK on the other hand also changes the shape of the cornea but rather than burning cells away permanently, we shift the cells temporarily. This shifting of the cells and improvement in vision lasts only as long as the patient continues the wearing schedule of the lenses. Although, OOK is temporary, its distinct advantage is that its effects are reversible, where surgery is not.
Another benefit of OOK is that its effects can be adjusted or modified. For instance, if a patients' myopia increases, we design a new lens to move more epithelial cells, creating more focusing power. Conversely, when a patient reaches their 40's, the ability to focus on near objects is reduced which is called presbyopia. OOK can be adjusted on one or both of the eyes to provide good distance vision but at the same time, improve a patients' ability to focus on nearby objects as well (called monovision).
Am I a candidate for OOK therapy?
OOK Therapy is suitable for a broad base of the population that requires vision correction. If you have light to moderate myopia, or a small amount of astigmatism you may be a good candidate. Candidacy Requirements.
What is the Therapy Process?
The therapy process begins with a review of your particular requirements and a trial to ensure the retainer is compatible with your eyes. Next custom retainers are manufactured based on a topographical map of your cornea. Your vision improves dramatically the first night with the retainers! Finally a series of follow up visits with your practitioner will monitor your progress. More Detail.