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Ortho-K remains effective alternative to refractive surgery

Issue: November 1995

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ANAHEIM, Calif.--While refractive surgery may be gobbling up all of the attention, a well known contact lens fitter said here that orthokeratology (ortho-K) is still a safe, effective option for correcting myopia.

--- Rodger Kame.

During a seminar at the International Vision Expo meeting, Rodger T. Kame, OD, who is in private group practice in Los Angeles and is past chair of the Contact Lens Sections of the AOA and the AAO, said that ortho-K deserves its place in the myopia correction market. "You have to give patients an option," Kame said, "and an excellent option is orthokeratology from plano to –3. Why not give them that option before they consider photorefractive keratectomy or radial keratotomy? It's reversible. It can be done on children. It can be a very important part of any contact lens practice."

Conventional ortho-K alternative

Kame uses accelerated ortho-K, which he said is fast, predictable and easy to "sell" to patients. While the technique is the same for accelerated and conventional ortho-K, Kame uses "reverse geometry lenses" for the accelerated method.

Kame refers to these lenses with steeper peripheries as reverse geometry lenses so ODs could not only "visualize how the lens looks mechanically," but could "reverse the thinking of their guidelines for regular lens fitting," he said.

The principles of accelerated ortho-K fitting are considerably different from conventional ortho-K and conventional lens fitting, Kame said, because the peripheral curves are reversed. For example, to tighten the ortho-K lens, rather than increasing the optical zone as with conventional fits, it must be decreased. And in ortho-K fits the diameter will affect how the lenses center. "To center the lens, you may have to increase the diameter. It's not unusual to use 10-, 10.5- or 11-mm diameter lenses," Kame said.

He added that prism ballast may need to be added to weight and center the lens. "A word of caution," Kame said. "When you do that, you're lacking rotation, so be prepared for lenses that center laterally a little more or develop three-nine staining."

Properly centering the lenses is crucial for full effect, Kame said. "To that end, sometimes it take some imagination and some tweaking of the parameters. Unlike conventional contact lens fitting, where you can take the lenses back to the lab and start modifying them, these have to be reordered."

The ultimate goal in ortho-K with reverse geometry lenses, Kame said, is to get similar corneal changes in terms of the central and peripheral relationship.

Introduce method in three steps

To introduce ortho-K to patients, Kame suggested a three-step approach structured over six months. Such an approach is not only easy for patients, but it also acquaints the novice ortho-K fitter to the nuances of ortho-K.

1. Patients wear conventional lenses so they can see the subtle improvement that lenses can create.
2. The patients should be fit aggressively with reverse geometry lenses.
3. They should be fit with an overnight retainer to maintain the effects.

Patients are more comfortable with this approach, he said, because they do not have to commit to a large fee right away.

--- Fluorescein pattern of OK2 lens.

When ordering OK Series lenses, Kame said he often requests two pair, with the second pair 0.5 D flatter. The initial lens often tightens because the cornea changes rapidly. A quick switch enables the fitter to maintain an optimal ortho-K fitting relationship.

Kame motivates patients by telling them that the longer they wear the lenses each day, the more lasting the effects will be. He sees them three or four days after fitting and monitors changes with corneal mapping.

"Mapping is very useful in helping patients adapt to these lenses, because you can see slight changes," Kame said. "But even without mapping you can use the fluorescein pattern and your K readings--especially the temporal K readings--for guidance."

Kame increases the wearing time up to three months. After patients have adapted, he reduces it to about four to six hours of wear. Then he settles patients into a lens schedule that fits their routine.