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Experience shows CK is safe, effective, clinically stable
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Conductive keratoplasty (Refractec, Irvine, Calif.) is an exciting new procedure for correcting hyperopia that was approved by the Food and Drug Administration in April 2002. Through CK, radiofrequency (RF) energy is applied via a handheld probe to increase the temperature of the corneal tissue. The treatment is introduced around the mid-periphery of the cornea, causing the corneal collagen to contract in a controlled fashion.
By applying the treatment spots in a circular fashion, a band of tightening is created, similar to cinching with a belt. This results in a steepening of the central cornea. The duration and intensity of each spot application is fixed, with the effect being titrated by varying the number of treatment spots.
The FDA has approved CK for the temporary reduction of 0.75 D to 3.25 D of spherical hyperopia in patients with less than 0.75 D of astigmatism who are 40 years of age or older. Treating any patients outside of these guidelines would be considered off-label use of the device, and patients must be counseled accordingly.
While CK is a thermal procedure similar in concept to laser thermokeratoplasty (LTK), it does not exhibit the regression seen with LTK. CK is more stable because it has a more consistent tissue temperature gradient than LTK and a deeper treatment (75% corneal depth with CK vs. 50% corneal depth with LTK).
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CK 1 hour postop: Radiofrequency energy is applied via a handheld probe to increase the temperature of the corneal tissue. The treatment is introduced around the mid-periphery of the cornea, causing the corneal collagen to contract in a controlled fashion. By applying the treatment spots in a circular fashion, a band of tightening is created, similar to cinching with a belt. This results in a steepening of the central cornea. (Reprinted with permission from Refractec Inc.) |
Safe and effective
We have been performing CK since July 2002 and to date have treated more than 250 eyes. We have found CK to be stable, effective and readily embraced by patients as an extremely safe refractive procedure.
CK patients make up a different patient population than what we see for LASIK. It is important to realize that the hyperopic patient population is large and often under-represented in the typical ophthalmic practice. According to the 1997 Baltimore Eye Study, there are more than 70 million hyperopes in the United States (compared to 60 million myopes), and 55 million are low hyperopes (below 2 D). They are therefore within the treatment range for CK. In addition, the most recent U.S. Census data show that more than 34% of the U.S. population is currently presbyopic (95 million Americans were 45 years of age or older in 2000). Correcting this population represents a huge practice opportunity.
Typical patient
At our practice, the typical CK patient is a 53-year-old man, a plano presbyope (distance refraction within ± 0.50 D of plano), who needs glasses for near only, has had great distance vision all his life and hates his reading glasses with a passion. These are the types of patients who have been told by their eye doctors that nothing can be done and they’re just getting old. It’s no mystery why these patients do not return for eye care.
In addition, these patients are risk adverse. They typically feel like their vision has been great all their life and that their distance vision is still great (even if it is not). Therefore, they are less accepting of surgical risks than myopes who feel like they have “always been blind.”
These hyperopic patients generally do not want LASIK and certainly do not want the invasiveness of the intraocular surgery that’s required to implant a multifocal IOL. CK has great appeal to this patient population. They appreciate the fact that it is accomplished without cutting, it uses no blade or laser, no tissue is removed, and the treatment is in the peripheral cornea, thus sparing the central visual axis.
A further breakdown of our first 175 eyes is provided in the chart. You will note that the vast majority of our patients received off-label treatment, with most patients receiving treatment for presbyopia. These patients tend to be very frustrated by their dependence on reading glasses, and their motivation is usually to improve their near vision. Any improvement in distance vision generally falls in the bonus category.
Patient expectations
Appropriate patient expectations are key. I tell patients that CK is a great procedure with a tremendous safety profile. For those patients undergoing a presbyopic correction, I tell them that it can restore “functional” or “daily life” near vision. I emphasize that CK is not perfect and does not completely eliminate most patients’ need for reading glasses. I tell patients that they should expect to continue to need readers for critical near tasks.
It is also important to stress to patients that both hyperopia and presbyopia are progressive conditions, and that patients will definitely need reading glasses more as they get older. But they will not lose the advantage they have gained from the procedure.
“Blended vision”
The way we accomplish the goal of functional near vision is by what we call “blended vision.” The way I explain blended vision is to tell the patient that we will treat the two eyes differently. One eye is treated for distance (or left untreated if the patient has good unaided distance vision), and the other eye (generally non-dominant eye) is treated for near. I use the term blended vision, as it avoids the negative connotation that monovision has in many people’s minds.
Blended vision with CK is different from monovision with contacts or laser vision correction in that the difference in the two eyes following CK is generally less than the difference between the two eyes in the other modalities.
For Your Information:
- InSight Lasik has been designated as a CK Center of Excellence by Refractec and is one of only three practices so designated.
- Refractec Inc. can be contacted at 5 Jenner, Suite 150, Irvine, CA 92618; (949) 784-2600 or (800) 752-9544; fax: (949) 784-2601; Web site: www.refractec.com.