tonometry
NCTs Ain't What They Used to Be
Don't believe everything you've heard. Today's non-contact tonometers are worth another look.
BY RENÉ LUTHE, Senior Associate Editor

Non-contact tonometers (NCTs) have a reputation that precedes them, and for many O.D.s, it's a reputation that renders the devices not worth their time. "They're not accurate," some complain, while others say that NCTs are only screeners, or that patients hate the air puff too much to bother with them. Yet, according to their fans, new models show significantly improved accuracy. They are easy to operate, tech-friendly and, to the relief of patients, they no longer use a hard air puff.

Goldmann rules, but . . .

Experts acknowledge that Goldmann applanation remains the preferred instrument for diagnosing and treating glaucoma. "No question that a Goldmann tonometric reading is superior to the NCT," says Richard S. Kattouf, O.D., D.O.S. "In a perfect world, using the Goldmann tonometer in conjunction with some form of optic nerve analysis would be ideal."

Yet NCTs are gaining ground. Neil B. Gailmard, O.D., M.B.A., F.A.A.O., claims that he's compared IOP measurements from recent NCTs with Goldmann readings on thousands of patients and found that NCTs are consistently within 1 mm to 2 mm. "If the NCT reads high, I know we have a problem that demands further testing," he says.

Dominic M. Maino, O.D., ME.d., F.A.A.O., agrees. Studies have shown that "the NCT was similar to Goldmann for most patients most of the time," he says. "In my experience, it's a fine substitute for those patients on whom you cannot perform Goldmann or Tono-Pen tonometry."

Diversify

However, confirming and correlating visual field data, nerve fiber analyses and optic nerve appearance with IOP remains key to accurately diagnosing, managing and following glaucoma patients. Andrew Gurwood, O.D., cautions that in glaucoma diagnosis, no one finding is more important than the sum total. "In the clinical setting, tonometry, no matter which one you use, represents but one piece of data," he says.

Liberate yourself

While Goldmann tonometric reading remains superior to NCTs, eyecare practitioners must consider other issues as well. Dr. Kattouf points out that in modern optometric practice, both independent and corporate doctors deal with a large volume of patients. The ability to delegate is key and NCTs can be a big help. While you can teach your techs to perform Goldmann, it's not necessarily as easy as it sounds.

For one thing, Dr. Kattouf says, "There's a practical problem of the number of exam rooms with slit lamps equipped with contact tonometers." Additionally, varying skill levels among staff, as well as staff turnover, complicate the issue further. "NCT is the easiest, safest and most reliable for most techs to perform because it's automated and computer verified," points out Dr. Gailmard. The more data that can be supplied by your techs, the more efficient and accurate you're likely to be.

Goodbye to all that

Another reason O.D.s commonly give for avoiding NCT is the infamous "air puff." However, the strong, unpleasant puff of air that lives on in most patients' minds belongs to the early model NCTs, some practitioners contend. "With the new technology available, the puff of air is almost unnoticeable," James J. Kirchner, O.D., contends. Dr. Gailmard agrees that today's NCTs "are very different. Patients nervous about undergoing NCT due to bad memories of the air puff now sit comfortably for two or three readings on each eye," he reports. He recommends having NCT done on your own eye by a new device at the next convention to see for yourself how much the technology has improved.

Dr. Gailmard adds that the new NCTs are quieter too, which helps how they are perceived because much of the patient apprehension in the past was due to the loud "clunk" noise made by the early models.

Some people!

Additionally, some practitioners caution that NCT is often a better choice for certain groups of patients. Practicality wins the day. "Because I examine many children and those with disabilities, I often use either the Tonopen or the NCT," says Dr. Maino. "In my experience, it [NCT] is a fine substitute for those patients."

Attitude adjustment

So consider putting your old NCT prejudices aside and trying out one of the recent models. They'll increase the data for your decision making, provide accurate screening and help free up your time.