Spotlight: ON TECHNOLOGY AND TECHNIQUE
Surgery in Cyberspace
Coming soon: a way to try multiple possible treatments and compare the outcomes -- before you operate on the patient.
By Christopher Kent, Senior Associate Editor

If you've ever dreamed of being able to try out surgical options ahead of time, you may not have to dream much longer. Within a year and a half, the multinational company MedRx expects to be beta testing an instrument capable of precisely recreating a patient's eye in cyberspace. This will allow you to perform multiple treatment alternatives on the cyber replica of the eye and compare the outcomes -- including the resulting visual acuity under different lighting conditions.

Stepping into cyberspace

The instrument, Smart SCan Plus, is the third link in a developmental chain starting with the currently available C Scan topography system. The next step, Smart SCan, will be available this spring. Smart SCan Plus, which MedRx hopes will be "the ultimate refractive diagnostic and planning instrument," should be available in 2002.

The forthcoming Smart SCan system will be similar in size and design to the currently available C Scan topography system, pictured above.

Smart SCan Plus will allow you to:

• Measure the total eye and optical system, quickly and accurately. Currently, most diagnostic instruments use one of four technologies to measure the cornea or optical system: topography, optical coherence tomography (OCT), ray tracing or wavefront aberrometry. However, each of these has limitations:
  • Topography can map the anterior surface of the cornea, but tells you nothing about the thickness or posterior surface of the cornea.
  • Optical coherence tomography can measure the thickness of the cornea, but not the topography.
  • Wavefront aberrometry can uncover flaws in the optical system, but can't localize them. (A floater or juvenile cataract, for example, can create the appearance of a corneal problem.)
  • Ray tracing can define how well the optical system is functioning, but can't measure its components.
    According to MedRx, combining all four technologies within a single instrument will allow the technologies to compensate for each others' limitations and create a complete set of accurate measurements describing the eye.
    Current versions of the instrument being tested by MedRx (which do not yet include wavefront aberrometry) measure the eye in 20 milliseconds or less. This speed effectively eliminates the problem of patient movement, resulting in high accuracy and reproducibility.
• Generate an accurate 3-dimensional replica of the eye in cyberspace. This 3-D replica can be pictured onscreen, allowing you to rotate it and observe it from any angle. (Smart SCan, the precursor to Smart SCan Plus, will be able to create a 3-D replica of the cornea, but not the entire eye.)
  The measurement data and the 3-D replica of the eye can also be preserved on an "i-card," that the patient will be able to take home for quick reference in any future exams.
• Try different treatments and compare outcomes. Smart SCan Plus's software system, called Cyber-i, will allow you to program different ablations of your patient's cornea, try implanting IOLs or intrastromal corneal ring segments (ICRs), and even place a contact lens on the "post-surgery" cyber eye.
  Smart SCan Plus (like this spring's Smart SCan) will display ablation outcomes in your choice of formats, including 3-D composite elevation and curvature maps with a translucent "ideal" cornea reference plane for easy visualization. (See illustration, below.) You'll also be able to view at least 15 different outcomes side by side onscreen, including cumulative outcomes of sequential ablations. (See illustration)
  In addition, Smart SCan Plus's advanced ray tracing software will make it possible to determine the corneal visual acuity produced by each alternate treatment under different lighting conditions. You and your patient can then decide which treatment will best meet the patient's needs.
• Compare your data to a worldwide database of previous outcomes to help you choose the best treatment. The database will allow you to look for other cases with the same corneal shape, density and problems. It will list doctors' names, the procedure they chose, the type of laser they used and the outcomes that resulted, along with the doctors' notes.
• Take any ablation data you've chosen and input it directly into your laser. This will ensure that the ablation is accomplished just as it was in cyberspace. (MedRx's goal is to allow Smart SCan Plus to work with all major refractive lasers.)

Getting there in steps

Because Smart SCan Plus won't be available until 2002, MedRx is making the technology available one step at a time:

• Step 1: The C Scan corneal topography system (currently available). MedRx chose to base Smart SCan Plus on the C Scan because of several design advantages, including:
  • The C Scan is the only topographic system that projects colored rings (rather than black-and-white rings) onto the cornea and measures the reflection. When reflected black-and-white rings overlap, the information can be difficult to analyze. Colored rings effectively solve this problem.
  • The C Scan uses triangulation to locate a reference point on the cornea; it then creates a reference plane and determines corneal elevation relative to that plane. (This is analogous to geographic maps that give elevation relative to sea level.) Because of this methodology and the speed at which the measurements are taken -- 20 milliseconds -- the results are extremely consistent and reproducible.
  • According to MedRx, the C-scan is the only system that measures the topography of the entire cornea in a single scan. The patented design of the C Scan's reflected rings eliminates the central unmeasureable area common to other topographers.
• Step 2: Smart SCan. MedRx will introduce the precursor to Smart SCan Plus this Spring. Smart SCan, scheduled to reach the market in April, will have many of the capabilities of Smart SCan Plus, but on a more limited scale:
  • Smart SCan will incorporate three of the four measurement technologies mentioned above: topography, optical coherence tomography and ray tracing.
  • Smart SCan will use the measurement information it collects to generate an accurate 3-D replica of the cornea (not the entire eye) in cyberspace. As with Smart SCan Plus, you'll be able to rotate the "cyber cornea" and look at it from any angle.
  • Like Smart SCan Plus, Smart SCan will display ablation outcomes in your choice of formats, including 3-D, and determine the corneal visual acuity produced by each alternate treatment under different lighting conditions.
    Because the advanced Cyber-i software system is still under development, Smart SCan will work with an optional, separate ablation planning system called MAPS. MAPS will let you try different ablations, singly or in sequence, and see the result. It won't project outcomes involving other possible treatments, such as implanting an IOL or ICRs. However, MAPS will be able to export the ablation plan you select to any major laser. (The MAPS system is also designed to accept input from many other existing topographic measurement tools, making it possible to link them directly to whichever laser you choose.)

A surgeon's perspective

Bruce Jackson, M.D., of the University of Ottawa Eye Institute in Ottawa, Canada, is one of the doctors helping to test the Smart SCan technology. "This is quite exciting, and very different from anything we've done in the past. Seeing the cornea in 3-D is remarkable -- it's a whole new experience.

"We now have the ability to take readings, plan ablations, see the results, make changes and plan more extensively. So far, our results correlate well with our predictions.

"This technology is excellent when addressing unusual conditions like keratoconus, which even wavefront systems have trouble with. We can also take patients who've ended up with less-than-ideal laser surgery results and determine an 'ideal' retreatment. In fact, we're treating patients who up until now would have been considered untreatable."

Dr. Rejean Munger, also of the University of Ottawa Eye Institute, is one of the designers of the Smart SCan software. "This really is a step forward in the way we think about refraction in the eye," he says. "It takes advantage of a number of new ideas on the visualization and presentation of information."

Dr. Jackson points out that limitations still exist. "Creating the 'ultimate' diagnostic device isn't really the holy grail, because what we correct today may not hold up later. The lens will change with time. Optical defects change even when the eye simply shifts focus from near to far. The cornea heals differently in different patients, and dry eye can affect outcomes. Plus, we still have laser limitations: Even if we measure the problem, can we precisely align and treat the patient with the same accuracy?

"Because perfection is probably impossible, the patient may have to chose between outcomes. But with this software, you can see the alternatives and sit down with the patient to chose the outcome he or she prefers."

Keeping an eye on the future

Kevin Dean, vice president of operations at MedRx, says that the company is about 80% of the way to completion of Smart SCan Plus. He also emphasizes MedRx's commitment to the healthcare professionals who'll use this technology. "Each step in the chain is upgradeable to the next level. In addition, starting with Smart SCan, MedRx will offer trade-in allowances for other devices in your practice that Smart SCan would replace."

MedRx has a number of other cutting-edge products under development, some of which will be unveiled later this year. In the meantime, for more information about C Scan, Smart SCan or Smart SCan Plus, contact Kevin Dean at MedRx at (678) 290-0909, or via e-mail at medrx@att.net.

A Smart SCan workscreen shows an untreated cornea (top left); a map of the ablation being considered (top, center); and screens showing the projected result in four different formats. Other formats can be selected from the data display list and shown simultaneously.

A Smart SCan screen shows the projected cumulative results of a series of four sequential ablations across the top of the screen (the untreated cornea is on the left). The two bottom images show the untreated cornea (left) and the cornea after the full series of ablations (right) in 3-D. Note the translucent reference plane in both images.

Smart SCan shows the cumulative outcomes of two possible treatment plans (each using several ablations), progressing from left to right (untreated cornea on left). A third treatment plan could be tried in row #3. All maps shown are elevation maps, but data can be displayed in any of several formats.

Are you aware of new products or technology that have made (or are likely to make) a significant difference in practice? Contact Christopher Kent at kentcx@boucher1.com to find out about possible coverage in a future issue.