The Ortho-K Network - All About Ortho-K

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All About Ortho-K

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OrthoKeratology (Ortho-K)

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Ortho-K is a non-surgical process which reshapes (flattens) the cornea of the eye using contact lenses to reduce refractive errors (nearsightedness and astigmatism). Accelerated Ortho-K uses reverse geometry contact lenses. Flattening the cornea reduces the focusing power of the eye. Since the amount of corneal flattening can be accurately controlled, it is possible to bring the eye into correct focus and compensate for the refractive error.. After the contact lens is removed, the cornea retains its flattened shape for part or all of the remainder of the day. A retainer lens must be used each day to maintain the corneal flattening, or the myopia will revert to the pre-treatment level. [ View Vision Demo ] Ortho-K is also successful for some degrees of farsightness by steepening the central cornea.

Yesterday
The procedure was first used over 40 years ago when eye doctors noticed that some contact lens wearers' vision improved after wearing their lenses.It has been reported in Chinese history that sand bags were placed on the eyes at night in an effort to prevent myopia though this was more likely to cause glaucoma. Initially, only old-fashioned, hard contact lens material (PMMA) was used. A series of lenses were needed, each lens flattening the cornea a small amount until the desired results were attained. This took months to years to accomplish.

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Today
Now, with the advent of space-age polymers, computer-assisted lathes, and technological advancement in the procedure, it is possible to achieve reduction of myopia in a matter of days. This high tech version of Ortho-K goes by many names. Among them are:

AOK - Accelerated Orthokeratology
CRT - Corneal Refractive Therapy ^(TM)
CCC - Corneal Corrective Contacts
EZM - Eccentricity Zero Molding ^(TM)
GVSS - Gentle Vision Shaping System ^(TM)
VST -- Vision Shaping Treatment^(TM)

Children and adults can be treated with Ortho-K because the principle of flattening the cornea is effective for both. Myopia control is used to slow or stop the increase in axial length of the eye that occurs in growing children who are becoming more nearsighted each year. This may result in a lower prescription, so the child won't have to wear the thick lenses he might otherwise require by the time he/she is a teenager.

Cornea
The cornea makes up about two-thirds of the eye's total power to focus the light precisely on the retina (receiving screen) which is located in the back of the eye. By slight modifications in the shape of the cornea, clear functional vision may be restored for a period of time.

This improvement is temporary, therefore lens wear must be continued on a prescribed wearing schedule to maintain the therapeutic effect of the myopia reduction. This flattening is accomplished by shifting the outer layer of the central cornea - the epithelium - more peripherally, thus flattening it. The amount of flattening or shift is approximately 6 microns per diopter of myopia. A micron is one millionth of a meter; a human hair is about 125 microns.There may also be some bending of corneal tissue to achieve flattening. This would be similar to pressing gently on a balloon producing a depressed surface.
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LASIK
Recently, several surgical procedures have been developed to attempt to accomplish the same purpose (i.e., changing the curvature of the cornea). Since the cornea is soft, it can continue to change shape as time goes by. The individual prescription may continue to vary leading to increased dependence upon eyewear within years to just a few months after the surgical procedure. Some surgical procedures (RK) produce scars causing surface irregularities on the cornea, resulting in permanent blurring that even glasses or contacts cannot eliminate. LASIK is less likely to produce scarring of the cornea and has become a hot topic in eyecare. Surgery is not an option for children or those whose vision is changing. It does not stop the progression of myopia in children or adults.

Conversely, Ortho-K is accomplished with a contact lens device. Since the eye is flattened and retains the flattened contour for a period of time the process is sometimes referred to as corneal molding. The mold is a specially designed contact lens. It is somewhat larger than a standard lens but not very different in appearance. Comfort is generally excellent. The lens is working as it is worn, whether you are sleeping or awake. The procedure takes just hours (in mild cases) to a few months (in very difficult cases) to reach good functional vision. At that point, the wearing time is gradually reduced until a minimal-wear time is established that maintains the corneal shape and good functional vision. This assures continued clarity without the gradual blurring that may accompany surgery. The cornea can easily be fine-tuned by minor modifications to the retainer mold.

Topography - videokeratography
Ortho-K utilizes precise instrumentation to accurately determine the corneal shape before treatment.

Ortho-K reverse geometry contact lenses change the shape of the eye

The corneal topographer "maps" the eye using thousands of points. The topographer enables the ortho-k doctor to design the lens for each eye instead of using "stock" lenses. These topographic maps or pictures are used to determine if the corneal shape is changing in the correct manner. The typical post-treatment map shows a central red ring (steepened area) surrounding the flattened area. This flat area must be centered over the pupil to provide maximum benefit.

Benefits
Ortho-K is not only an excellent alternative to the wearing of spectacles, but it also frees the individual from the distractions caused by perspiration, dust, wind weather and temperature. There are no more blind spots caused by frame or lens edges. It is great to wear "regular" fashion sunglasses, to get up at night or in the morning and see, to go swimming and skiing, to drive in a convertible with the top down, to work in the dust, grass or in the garden, and to be able to see in cases of emergencies. Ortho-K might open new horizons to you. People in occupations that are hindered by the use of glasses or contacts may be good candidates for Ortho-K - pilots, policemen, firemen, etc. Be sure to check with the regulations of your employer prior to undergoing Ortho-K.

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The Process
The Ortho-K specialist measures the curvature of your cornea using the corneal topographer. It is like having your picture taken and is painless, taking about five minutes.Some doctors use software to help design the lenses and diagnostic lenses may be placed on your eyes to help determine the proper lens. Contact lenses for Ortho-K have a reverse geometry design.

The central portion of the contact lens fits closer to the eye than a standard contact lens - exerting a gentle pressure. It doesn't touch the cornea as there is a tear layer protecting the eye.The reverse geometry part of the lens surrounds the central visual zone and is further away from the cornea than standard lenses allowing room for the shift of epithelium.

View Flash Demo

If your doctor prescribes overnight Ortho-K, expect results immediately. Your vision should be markedly improved after the first night.During the first few days or weeks your vision may fade later in the day. Improvement should be noticed each day.

Generally only one pair of lenses are needed for the accelerated therapy but additional lenses may be required to achieve desired results. You will probably want an extra pair of lenses at the end of therapy in case of loss. Your vision will regress to pre-treatment levels while waiting for a new lens to arrive.

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Why Haven't I Heard About Ortho-K?
The practice of Ortho-K requires a great deal of technical skill, specialized equipment and considerably more office time and is therefore more costly to the patient. Many practitioners don't consider myopia control worth the time and effort. If a doctor is not trained in Ortho-K it will not be an option or suggestion during an eye exam. It is easier to offer contact lenses, glasses, or refractive surgery to correct vision. And Ortho-K doesn't produce a permanent result requiring retainer lenses to maintain the improvement. That isn't bad. Because it isn't permanent, it is reversible.

Who Is a Candidate? - Indications
People of any age who have low to moderate amounts of myopia or astigmatism. Many doctors are comfortable treating myopia of -6.00 diopters prescription or less. Ortho-K is best suited for myopia, but studies are underway for hyperopia (farsightedness).

Who Is Not a Candidate? - Contraindications
Acute and subacute inflammations or infection of the anterior segment of the eye.
Any eye disease, injury or abnormality that affects the cornea, conjunctiva or eyelid
Severe insufficiency of tears - dry eyes.
Corneal hypoesthesia - reduced corneal sensitivity.
Any systemic disease that may affect the eye or be exacerbated by wearing contact lenses.
Allergic reactions of ocular surfaces or adnexa which may be induced or exaggerated by wearing contact lenses or use of contact lens solutions.
Any acute corneal infection - bacterial, fungal or viral.

FDA - overnight Ortho-K

Overnight Ortho-K has been approved by the Federal Drug Administration.

Many lens designs have been approved by the FDA. Several lens materials used for overnight Ortho-K have also been approved. Ortho-K has been practiced safely for over 40 years and overnight Ortho-K for 15 years.Clinical studies to see more data on the risks and benefits of the overnight procedure are underway.

Safety
Consider this. Daily wear contacts are worn 12-16 hours per day. Extended wear contacts are worn 24 hours per day. Ortho-K overnight lenses are worn 8 hours per day. Which is safer?

Is Ortho-K in your future? Only you and your eye doctor can decide that. To find out if you are a candidate for accelerated Ortho-K, contact your Ortho-K specialist.

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