Wavefront technology breathes new life into refractive surgery

While the refractive surgery market remains relatively small, long-term prospective studies comparing custom ablation to contact lens use may help increase its appeal.

Issue: June 15, 2005

ByDaniel S. Durrie, MD

There is no doubt that our refractive results are better than they have ever been, in large part because of improved diagnostics and ablation profiles from the manufacturers. We owe a lot to wavefront analysis and custom lasers. Also, as Jack T. Holladay, MD, MSEE, has long pointed out, we now know we should be looking at the shape of the cornea to help define the ideal optics.

To understand the importance of wavefront analysis, take a typical case of someone who appears to have straightforward myopia and wants 20/20 vision without the use of glasses. With wavefront, you get a picture that can accurately tell where the defects are and where to apply the pulses. Using the Shack-Hartmann aberrometer, you get a series of dots that can show you that this patient does not present a round dome like a typical myope would. From the wavefront analysis, you can see that the dots are asymmetric.

Postoperatively, the wavefront map can show you that the dots get wider as the cornea gets flatter, but they are nice and even. You can tell that the patient is going to have great visual results. We truly can improve the optics of the cornea with this technology.

Moving in right direction

With wavefront analysis and wavefront-guided treatment we are able to decrease the incidence of lower-order aberrations, such as sphere and cylinder, as well as higher-order aberrations. In the past, we could improve lower-order aberrations but we were also increasing higher-order aberrations at the same time. Now we are moving in the right direction with this technology.

We have not achieved perfection, but at least we are not going in the wrong direction any longer. Refractive surgery is a lot better than it was.

With this technology we can take patients with bad optics, customize their treatment and produce dramatic results. This includes patients who have previously undergone multiple refractive surgeries and are left as “ocular cripples,” in that they cannot be corrected with glasses and cannot tolerate their hard contact lenses. We can help many people with this technology.


Before wavefront-guided refractive surgery, note the irregular spacing of the points on this Shack-Hartmann image (left). Postoperatively, the spacing is much more regular. Images: Durrie DS

Megatrends

Expectations keep increasing on the patient’s end, compared to when I started 25 years ago. First, patients wanted thin glasses instead of thick ones. Next, they wanted 20/40 vision, then 20/25 vision, and now nothing less than 20/20 vision. These days, patients want better near and distance vision without glasses. I think the technology is helping us achieve these goals.

There is a common perception that refractive surgery has slowed down because we have already treated so many people. In actuality, we have barely scratched the surface. We are still stuck at 2% to 5% of the potential market and have not been able to move past that mark.

In 2005, of the total market of people who need distance refractive correction, people who wear glasses make up 67% of the market, those who wear contact lenses make up 30%, and those who opt for refractive surgery are still only 3%.

Looking at trends over the past 25 years, the popularity of contact lenses has grown twice as fast as refractive surgery. We should consider why we are not increasing market acceptance.

Quality of vision

Soft contact lenses do not provide as good optics as modern refractive surgery, and they have a higher complication rate. This is a point we are missing in terms of educating patients. A major challenge to refractive surgery is whether we can establish that the quality of vision can be better than with spectacles and contacts and potentially safer than soft contact lenses. The answer is “yes,” because the new technology can make it happen, but we need controlled studies to document the results.

We need to get the message out that with modern wavefront-guided refractive surgery patients have a better-than-50% chance of seeing better than they did with glasses. That is a big selling point, but most people are afraid to say it. Our technology can back that up.

We really do have better quality of vision with modern refractive surgery than we do with glasses. In our clinical studies with Alcon CustomCornea with IntraLase, 70% of patients have better best corrected visual acuity postoperatively than preoperatively. We are also improving contrast sensitivity in many patients.

Soft contact lenses have been reported to have complication rates as high as 5%. The contact lens industry does not want to talk about that, but it is a fact. Most ophthalmologists have seen patients with corneal infections with contact lenses that can lead to significant vision loss.

I am currently involved in the early stages of putting together a 10-year, prospective, randomized study of modern contact lenses vs. modern refractive surgery. The study will evaluate quality of vision, complications and value to the patient. We need prospective studies of contact lens use vs. refractive surgery to prove this. These studies would need to be conducted by the National Eye Institute because they could not be done by manufacturers or by potentially biased refractive surgeons. They need to be done properly. It would be great if in the next 10 years we could establish that refractive surgery is the better alternative to contact lenses for all these reasons I have laid out.

Technology has advanced to the point where refractive surgery can compete directly with glasses and contacts. We need to conduct the appropriate studies to provide the information the market is lacking.

chart

When to perform surgery

Another major issue is when to perform refractive surgery. In the past we have done it when patients were failing with glasses and contact lenses. Now we can start considering it as soon as the patient is old enough: ie, when their eyes have stopped growing and have stabilized.

We do not wait for people to turn 40 before we straighten their teeth. We wait until the dentist says they can go to the orthodontist. That is the direction we are headed with refractive surgery. We can correct the congenital defects in people’s eyes now with refractive surgery. For a 20-year-old patient, this represents a true value, because he will not have to wear glasses or contact lenses for his lifetime.

We can demonstrate the cost savings for a 20-year-old who undergoes premium refractive surgery compared to the cost of glasses and contact lenses, plus inflation, over time. The break-even point, in my calculation, is 7.4 years. After that, the patient is ahead for the rest of his life. We need to underscore the economics of this issue.

Another important point is that a 20-year-old patient will not have any lens aberrations. A wavefront scan will pick up the patient’s corneal aberrations, and only those will be corrected. With a patient who has a nuclear cataract, some aberrations are in the lens and some are in the cornea. My argument is that we should be eliminating everyone’s congenital aberrations in the cornea early on in life. Then, down the line, it will be easier to calculate IOL power because there will not be any corneal aberrations. Only the lens aberrations will be present.

Performing refractive surgery on younger patients is better not only economically, but also medically, scientifically and optically.

Market volume

I have been involved with refractive surgery since 1983. Over that time I have noticed that, irrespective of the strength of the market, irrespective of the state of the economy, about the best we can hope for is to have around 1.5% of prospective myopic candidates come in for refractive surgery every year. This is with our optimal promotional efforts. About every 5 years some analyst will come forward and say, “With this new technology it’ll be 5% of the myopes who are having surgery.” But that is just not the case.

Market volume depends on the size of the pool of prospective patients.

The patient’s fear of the outcome is also a major factor. We just have not provided the comfort that this surgery is safe to patients who can afford surgery and who are educated about it. If we can provide convincing data that modern refractive surgery is safe, effective and a long-term value, the market growth will be significant.

An important step will be a study comparing surgery to contact lenses, because patients can relate to the fact that contact lenses are an alternative to surgery. If we can show them in a head-to-head comparison that we compete well on optics, value and complication rates, that will help to prove our case.

For Your Information:

Daniel S. Durrie, MD, can be reached at Durrie Vision, 5520 College Blvd., Suite 200, Overland Park, KS 66211; 913-491-3737; fax: 913-491-9650; e-mail: ddurrie@durrievision.com. Dr. Durrie is a clinical investigator for IntraLase. Dr. Durrie is a paid consultant for Alcon.