Spotlight ON TECHNOLOGY & TECHNIQUE

A Test to Distinguish Viral Conjunctivitis

With 90% accuracy, doctors can tell when adenovirus causes red eye.

By Bill Kekevian, Associate Editor

Darrell White, MD, a founding ophthalmologist at Skyvision Center in Westlake, Ohio, says he sees nine or 10 red eyes a day. In some cases, it’s easy to distinguish between viral, bacterial or allergic conjunctivitis. However, some patients present with signs and symptoms of all three entities.

“We doctors see red eyes come into our practices all the time,” he says. “Everybody thinks they can be really spot-on when they make a diagnosis.” But, as Dr. White and his team found out, that may not always be the case.

That’s what he learned while researching a new diagnostic device, the AdenoPlus, from Nicox. It’s a point-of-care diagnostic tool designed to detect the adenovirus. Dr. White says his team found it to be very accurate with better than 90% sensitivity and specificity in more than 90% of cases and very few false positives or negatives.

Putting it to the Test

In addition to seeing patients, Skyvision Center houses a business process research lab. It’s a program in which Dr. White’s team can evaluate what he calls “good products that are underperforming” in an effort to re-engineer them or find ways to make them more marketable. Nicox approached Dr. White for his advice on the AdenoPlus.

During these tests, Dr. White and his team were surprised to find they were not so spot-on in diagnosing conjunctivitis. “Those of us who are early users of this technology discovered we’re not right as often as we thought,” Dr. White says. Their results found that doctors’ diagnoses of presumed adenoviral conjunctivitis were accurate about half the time.

The AdenoPlus received 510(k) FDA clearance in 2011, the first FDA-cleared and clinical laboratory improvement amendment-waived test of its kind.

Now that it’s out of the lab and in the exam room, Dr. White says he leaves the testing to his technicians.

A Four-Step Process

The test comprises three components and involves four steps. Each test kit contains a sterile sample collector, a test cassette and a buffer vial. The steps are:

■ Take a sample. Ocular anesthetics won’t interfere with the results, the company says. Taking the sample involves dabbing and dragging the sampling fleece along the palpebral conjunctiva six to eight times, then resting it on the conjunctiva for another five seconds to moisten it. Upon saturation with tear fluid, the fleece will glisten.

■ Assemble the test. The fleece is placed into the sample transfer window of the test cassette body. The operator presses firmly where indicated until it double clicks.

■ Run the test. Tests should be run within 24 hours of acquiring the sample. The Skyvision staff report the test takes slightly longer than 10 minutes to run. Running the test consists of first taking the buffer vial and removing the cap. The operator then immerses the absorbent tip for at least 20 seconds, and then places the test horizontally on a flat surface for 10 minutes. A purple fluid wave will move across the test window while the test runs. After 10 minutes and once the window turns white, the test is ready to read.

■ Read and interpret. Two lines that appear in the result window, the control line and the result line, indicate the results. Three results are possible:

► Both a blue line in the control zone and a red line in the result zone indicates a positive result, even if the red line is faint, incomplete or uneven.

► A single blue line with no red at all indicates a negative result.

► If no blue appears, the test may be invalid. In this case, try re-immersing the absorbent tip into the buffer vial for an additional 10 seconds. If a blue line still does not appear after 10 minutes, the patient must be retested.

Dangers of Conjunctivitis

Dr. White calls a 14° F morning in Ohio “upper respiratory illness time of year.” That, combined with families and schoolchildren fresh off winter breaks and interstate traveling, means a higher likelihood of viral infection.

Getting a diagnosis right is important, Dr. White says, in helping target the issue with specific treatments and in keeping patients from developing drug resistant bacteria from unnecessary antibiotic exposure. OM