instrument focus

The Complete Picture

Device provides objective functional measurement of vision.

Ansel T. Johnson, O.D.

To determine vision functionality, we’ve long employed eye charts and visual field testing. Because these tests are subjective, however, we may not be getting the complete picture of the patient’s vision. The Diopsys Neuro Optic Vision Assessment (NOVA)-Visual Evoked Potentials (VEP) Vision Testing System, from Diopsys, Inc. provides this complete picture.

“Thus far, this device has aided me in the early diagnosis of glaucoma suspects, glaucoma itself, optic neuritis, multiple sclerosis and traumatic brain injury, enabling early intervention.”

Overview

The Diopsys NOVA-VEP Vision Testing System is an in-office device (available in both a fixed protocol [NOVA-LX] multi-contrast stimuli and a user-defined protocol configuration [NOVA-TR]) that employs VEP to objectively measure the complete visual pathway’s (e.g. the anterior segment to the visual cortex) responses. The device’s dimensions: 24” x 24” (approx.) on a base with locking wheels, weight: 120lbs. I believe a smaller and lighter version with a more compact CPU can be created.

VEP is the measurement from electroencephalogram readings of the scalp’s occipital area due to retinal stimulation via a pattern or flash of light at half-second intervals. A computer monitor provides this light stimuli and then averages the electroencephalogram response of multiple consecutive patterns or flashes. In other words, the patient doesn’t have to say a thing.

In the Diopsys NOVA-VEP Vision Testing System’s case, VEP waveforms are represented on graphs using amplitude and time measurements. Then, the device provides quantitative information to aid in the management of ocular and visual deficits. In addition, the NOVA-TR module both reports and documents intervention outcomes when you perform testing post-prescribed management. (Artifact detection aids in noise cancellation and accurate data acquisition/analysis, and color-coded overlay charts are provided for test result comparison.) The results of both modules complement anatomic data, such as digital fundus photography, further aiding in management decisions.

Thus far, this device has aided me in the early diagnosis of glaucoma suspects, glaucoma itself, optic neuritis, multiple sclerosis and traumatic brain injury, enabling early intervention. The device can also help detect neuro-visual disorders, such as amblyopia, making it ideal for use on children age six months and older.

Procedure

While the patient is seated, wearing his best-corrected spectacles or contact lenses, the operator (you or a staff member) swabs the patient’s forehead, temple and occipital lobe (back of the head) with skin prepping gel. Then, the operator applies electropad gel and electrode patches to these areas. The patches are connected by wire to the Diopsys NOVA-VEP Vision Testing System. (To get the best results, the electrode patches must be directly on the skin. Therefore, prior to the Diopsys appointment, we tell patients not to arrive with hair weaves, braids or wigs. To accommodate the hairstyle issue, I am hoping some sort of helmet or other attachment could eventually be used.)

Next, the operator measures the distance from the patient’s face to the device’s screen to ensure the target size is calibrated to the patient’s distance. (The standard distance is three feet). The non-tested eye is then patched or covered.

Once the device confirms contact from the electrode patches, the operator presses a button to begin the testing.

Now, the operator instructs the patient to look at the device’s display monitor, and a series of checkerboard patterns appear while the device plays music to maintain the patient’s attention.

Total testing time is 5 min. It takes 38 to 53 seconds per eye, plus the prep time.

In my practice staff administer the test, and print the results in color for the patient’s record. Then, I make notes directly on the test results, and scan the document into the patient’s EHR. That said, you can connect the Diopsys NOVAVEP Vision Testing System to a practice computer network to export the results in PDF and save them to the patient’s EHR.

Training

A Diopsys sales representative presents for two training sessions. The first one, at which he covers the tests’ purpose, applications and operation, takes a couple hours. The second session, at which he assesses you and your staff’s ability to correctly operate the System, takes roughly an hour. In addition, the device comes with an instructional manual and 50 patient education brochures. Finally, help desk consultation is very accessible during business hours.

Return on investment

The device costs $35,850 ($4,995 per additional module — the NOVA-TR). I have the NOVALX and the NOVA-TR module. Separate purchases: The adhesive patches ($80.00), gels for the patches ($18 for a 4oz jar, $33 for an 8oz jar), skin preparing gel ($23) and device wires ($22 per set). The company does initially supply these items with the Diopsys NOVA-VEP Vision Testing System purchase. My initial supply lasted a couple months. Then, we ordered a six-month supply of these items, which cost roughly $700. Since then, we pay less than half of that for six months, as we do not have to replace all supplies at the same time.

We began using the Diopsys NOVA-VEP Vision Testing System in June 2011, and reached a return on our initial financial investment in April of this year. The CPT code for the Diopsys NOVA-VEP Vision Testing System is 95930 Visual Evoked Potential. The Medicare allowable reimbursement in the Chicago area is about $159. Based on five-year financing, only about five Medicare patients need to take the test per month for you to reach a break-even point. That said, I have always thought that any technology we bring into our office should pay off substantially more than simply breaking even on the monthly financing. In other words, we bought and use this device because it greatly aids in our decisionmaking regarding patient care, just as OCT has revolutionized the way we provide retinal care. OM