Overnight corneal reshaping increasingly popular option

Issue: July 2005

ByJennifer Byrne

Overnight orthokeratology, also known as corneal reshaping, is proving to be a viable option for myopic patients who wish to avoid refractive surgery. The procedure, which is still in its early phases, has begun to gain popularity in other countries, according to Craig Norman, FCLSA, director of the contact lens section of the Department of Ophthalmology, South Bend Clinic.

“I think that the introduction of modern overnight ortho-K is really still in its adaptive period. Awareness is building among eye care practitioners and among patients,” Mr. Norman told Primary Care Optometry News. “It is basically building up a base of who will be fitting and using these ortho-K shaping lenses, and who they are best indicated for. In other parts of the world, especially in countries where there is higher amounts and degrees of myopia, it’s actually a very common method of treatment.”

Who is a good candidate?

Mr. Norman said the best candidates for ortho-K are those who either want or require the ability to have daytime vision free of either spectacles or contact lenses. He said patients who are very active, who are involved in sports or athletics, who work in dirty, dusty environments and who have dry eyes would be good candidates for ortho-K.

Craig Norman [photo]
Craig Norman

“Also, any patients who are just unable to successfully or comfortably wear contact lenses during the day would make good candidates,” he said.

Mr. Norman also distinguished those patients who would be good candidates for ortho-K from those who would qualify as LASIK candidates.

Refractive surgery candidates are limited to those who are 18 years of age or older, Mr. Norman said. “Additionally, some patients are fearful of the surgical process,” he said. “While LASIK is highly successful, it is also a permanent procedure. In contrast, the process of overnight ortho-K is reversible.”

Mr. Norman said once the use of the overnight corneal reshaping lenses is discontinued, the cornea returns to normal, and the patient has all vision modality options available to him or her once again.

“The last issue is that of cost,” he said. “LASIK tends to cost about twice as much as overnight ortho-K.”

Visual outcomes

“The Paragon CRT (Paragon Vision Sciences, Mesa, Ariz.) is approved for up to –6. D, and the Bausch & Lomb Vision Shaping Treatment (Bausch & Lomb, Rochester, N.Y.) is approved up to –5. D,” Mr. Norman said. “And the amount of astigmatism that can be corrected for both of them is about –1.5 D.”

He said the visual outcome achieved will largely depend on the extent of the patient’s nearsightedness. For patients with higher amounts of myopia within those limits, Mr. Norman said, correction in the area of 90% to 100% can be expected. “Patients who are in the lower areas of myopia can be corrected to 20/20 or better predictably,” he said.

The amount of prescription, as well as small differences in lens design, will influence how quickly the process takes place, Mr. Norman added. “For instance, if a patient has 2 D to 3 D of nearsightedness, during the first night, he or she should be able to achieve 100% correction,” he said. “If somebody is a 4-D to 6-D myope, you can expect that it is going to take a period of days (or even weeks) before the full treatment occurs.”

For people with presbyopia, Mr. Norman said the correction process is very similar to the strategy for correcting presbyopia through refractive surgery. “That is, you can either correct them completely for distance and have them wear reading glasses, or you can slightly undercorrect for distance and allow them to still be able to read,” he said. “Or you can use the monovision approach, just as in refractive surgery.”

Paragon CRT

The first U.S. Food and Drug Administration-approved lens system for overnight Corneal Refractive Therapy (CRT), the Paragon CRT system, uses a diagnostic dispensing system.

“In this system, the process of determining the best lens for the patient is accomplished by taking ocular measurements,” he said, “and after the ocular measurements, choosing a lens from a fitting set of 100 or more lenses. Then, the practitioner places the lens on the patient’s eye to determine the best fitting relationship.”

Mr. Norman said if the first lens does not achieve the proper fitting relationship, the practitioner can then go back to the inventory and choose the next lens. “So, their fitting system is enhanced by the ability to immediately change the lens within the office,” he said, “but requires the practitioner to invest in that fitting system to be able to use it.”

Bausch & Lomb VST

Mr. Norman said the Bausch & Lomb Vision Shaping Treatment (VST) is actually an umbrella term for a series of different lens designs.

“While Paragon actually manufactures the finished lenses, Bausch & Lomb and its subsidiary, Boston brand group, don’t actually fabricate the finished lenses,” he said. “They make gas-permeable lens materials and lens care solutions, and their network of authorized laboratories make the custom ortho-K shaping lenses.”

Corneal reshaping: This photo shows a well-centered lens being used for corneal reshaping.
Image: C Norman

Bausch & Lomb received FDA approval last December for VST. Within that approval, these four lenses qualify:

the BE Retainer Lens
the DreamLens
the Contex OK Lens
the Euclid Systems Emerald Lens

The primary difference between these two approaches to corneal reshaping is the fitting systems, Mr. Norman said.

“With VST, the eye care practitioner actually has three options for choosing a fitting method appropriate for their individual practice,” he said. “For instance, with one of those designs, you simply can use keratometric measurements (“K” readings) and spectacle prescription to determine the initial shaping lens. With another design, diagnostic lenses are used to determine what intial shaping lens design should be ordered.”

Another option involves using an inventory fitting method similar to the Paragon CRT system, he said.

A third approach is the use of a software design system that uses topographical measurements to determine the initial ortho-K shaping lens.

Equally effective

Mr. Norman said although these various designs use different fitting approaches, these two types of overnight reshaping are equally effective, and both are quite promising. “The FDA study shows them to have similar results,” he said. “The principals of how the lenses work are exactly the same,” he said.

Both systems require specific practitioner training prior to use. “The FDA has mandated a level of training and certification,” Mr. Norman said. “So before doctors can get involved in this, they need to undergo a certification program that demonstrates their understanding of corneal reshaping treatment.”

For Your Information:

Craig Norman, FCLSA, is director of the contact lens section at the Department of Ophthalmology, South Bend Clinic. He can be reached at 211 North Eddy St., South Bend, IN 46617; (574) 237-9336; fax: (574) 277-8659; e-mail: craignorm@aol.com. Mr. Norman is a paid consultant for Bausch & Lomb.

Paragon can be reached at 947 East Impala Ave, Mesa, AZ 85204-6619; (480) 892-7602; fax: (480) 926-7369; www.paragonvision.com.

Bausch & Lomb can be reached at 1400 N. Goodman St., PO Box 450, Rochester, NY 14603-0450; (800) 553-5340; (585) 338-6000; fax: (585) 338-6896; Web site: www.bausch.com.