Another Look at Ortho-K
Another Look at Ortho-K | Orthokeratology, Ortho-K, CRT, Corneal Refractive Therapy, Corneal Reshaping Therapy, Overnight Vision Correction, Tommy Ducklo, Jeffrey Jessup, Ducklo EyeCare, Jessup Eye Care

Dr. Tommy Ducklo

An Alternative Option for Improved Vision

 

 Orthokeratology — sometimes referred to as corneal reshaping or molding — isn’t a new concept, but improvements in lens manufacturing technology and design have prompted a resurgence in popularity for the vision correction method that involves wearing rigid lenses to reshape the curvature of the cornea over time.

“Orthokeratology is the science of changing the shape of the cornea to reduce nearsightedness,” explained Tommy Ducklo, OD, owner of Ducklo EyeCare.“

“We do a lot of work with the procedure,” Jeffrey Jessup, OD, founder of Jessup Eye Care, said, “and one of the things we find is that it’s not well known.” He continued, “The idea … the concept of changing the shape of the cornea with a contact lens … has been around quite awhile. Now, in more recent years, we have new materials that lenses are made of making them more comfortable and safer.”

Ducklo said rigid gas permeable (RGP) lenses allow the cornea to receive as much oxygen as needed, which makes them safe for overnight wear. Although RGP lenses are not as comfortable as soft lenses for daytime wear, the issue of ‘feeling’ the lens is minimized while sleeping. “If I put a gas permeable lens in one eye and a soft lens in the other, you’d say ‘get that gas permeable lens off!’” Ducklo noted. However, he continued, “Gas permeable gives you the best vision out there … it’s the best by far.” Newer generations of RGP lenses have focused on improved comfort with some using the rigid structure in the center surrounded by a soft contact outer ring.

In addition to improved oxygen permeability and comfort, manufacturing technology has greatly improved. Corneal topography allows for close monitoring as the cornea’s shape changes. Automatic lathe cutting also allows for an exact curve on custom RGP lenses. “In the old days,” noted Ducklo, “you cut those curves in the back surface of the lens and then had to polish. Before, you might lose some of the definition of the curve with the polishing process.”

Ducklo said orthokeratology changes the same structure as LASIK, but the corneal molding effect is temporary so the lens has to be worn nightly or every-other-night to maintain optimal daytime vision without glasses or contacts. He added LASIK was also approved for much higher levels of nearsightedness. 

Jessup said, “We really like LASIK. It’s a great technology, but we find for some it’s 1) not appropriate, 2) they are afraid, or 3) they can’t handle the expense.” Orthokeratology offers a non-surgical alternative at a price that is significantly lower than LASIK but considerably higher on the front end than disposable soft contact lenses. However, once a patient’s cornea is reshaped, a pair of maintenance lenses often last for several years unless the vision prescription changes. If a problem occurs with Ortho-K, the patient simply stops wearing the lens.

One patient category where Ortho-K is especially beneficial is in children. “A lot of children are at that stage where their myopia is progressing, sometimes rapidly, and they are not at a point where LASIK is appropriate,” explained Jessup. He added recent studies have indicated the use of orthokeratology might also have extended benefits in terms of slowing or halting the degree of nearsightedness.

“The gas permeable lens is really the only thing we have available to us that will attempt to slow down the progression of myopia,” Ducklo concurred. He added that in addition to the visual benefits, Ortho-K at night was also a popular choice for children because it allowed them to play sports and lead active days without worrying about glasses or contacts.

Orthokeratology, however, has a relatively narrow field of qualified candidates. Paragon Vision Sciences, manufacturers of Paragon CRT®, was the first to receive the Food and Drug Administration’s approval for overnight corneal refractive therapy for the temporary reduction of myopia in 2002. The approved indicated use is up to -6.00 diopters of myopia with or without astigmatism up to -1.75 diopters. Ducklo added that he doesn’t like the outcomes at the outside range and typically cuts off use between -3.00 and -4.00 diopters. He also said that pupil size is very important. “If the pupil goes beyond the treatment zone, you’ll get halos,” he noted, adding this is true for LASIK or CRT.

Jessup pointed out Paragon CRT, for which both he and Ducklo have been certified, is only one approach to orthokeratology. Both optometrists also use other options including those that are custom made for individual patients when a stock lens isn’t optimal.

Yet another Ortho-K approach is the BE Retainer®, a design partner under Bausch & Lomb Vision Shaping Treatment. The lens is billed as an overnight eye “retainer,” similar in concept to an orthodontic device. Known as optimal orthokeratology (OOK), the FDA-approved therapy reshapes the surface of the eye by controlling the shape change of the epithelium to alter refraction. According to the corporate website, the OOK retainer doesn’t touch the cornea. Instead, it sits on a layer of natural tears, and the tiny forces applied by the tears squeezed between the retainer and cornea supplies the needed tension to reshape the surface.


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