Both structural and functional testing play an important role in the diagnosis and management of glaucoma. The data acquired through these tests, which are often performed by the ophthalmic staff, can help the doctor in making critical decisions for managing patients who have glaucoma.

Functional testing demonstrates how glaucoma affects a person’s vision and includes visual field (perimetry) testing. Structural testing can show changes in the optic nerve and retinal nerve fiber layer. These include tests such as fundus photography, optical coherence tomography (OCT), and OCT angiography.

Functional and structural testing ultimately work together in making a diagnosis and treatment plan, says Jacob Brubaker, MD, a glaucoma and anterior segment surgeon at Sacramento Eye Consultants in Sacramento, CA.

“Structural tests like the OCT allow us to quantify the structural aspect or define numerical values and determine if things are progressing in a way that functional testing alone will not do,” he explains. “There should be a correlation between structural and functional testing. For instance, if you have a deficit on the visual field, you should have RNFL loss on the OCT. But if they don’t match, something else could be going on.”

Dr. Brubaker adds that structural testing will also pick up early signs of a problem before there may be any visual field concerns. As far as early detection and stopping the progression, this is instrumental.

“For the glaucoma suspect or the mild patient, structural imaging is our best chance of catching something early, even while there is still nothing from a visual field deficit,” he continues. “In addition, because structural testing is objective, assuming it was a good scan, it can provide assurance even with a difficult patient who had an unreliable visual field test.”

The key, of course, is a good scan. For this, it’s important that staff recognize the valuable role that they play in the process, Dr. Brubaker says.

“These tests are dictating our next steps in glaucoma management,” he adds. “The reliability and the quality of the test is quite crucial to the patient’s therapy and staff should be made aware of this.”

Functional tips for techs

Even with all of the advances in technology, good scans still hinge on the proper administration of these tests. While ophthalmic technicians are tasked with many responsibilities throughout the day, it’s important not to overlook the importance of each test they perform.

As far as functional testing, Jillian Paulson, COA, lead ophthalmic technician with Chu Vision Institute in Bloomington, MN, says that providing good patient instruction is key, particularly with the visual field testing.

“It can be a daunting test for a patient but it’s even more cumbersome if the patient isn’t educated on what they’re doing,” Ms. Paulson says. “Setting up appropriate expectations and being clear about where they should be looking is critical to success. I have found that doing the heavy lifting on the front end and helping the patient to understand what they’re doing and why they’re doing it helps the test to go more smoothly once we start.”

Ms. Paulson says that it can help technicians to experience the test themselves.

“It helps to understand what the patient is seeing and experiencing,” she says. “You’ll notice how when you stare at a light for so long that your vision can go dark, which can be scary for a patient. Experiencing it yourself allows you to better instruct the patient.”

Nicole Smith, COT, CTC, OSC, clinical training manager for the Cincinnati Eye Institute says that “explaining the test in a way that the patient understands” has helped her to ensure patients are paying attention and clicking the button when they should.

“We let them know that we are looking for very subtle changes in their visual field but that these are really important to preserving their vision,” Ms. Smith continues. “We explain that they are going to experience some very bright light at times. A prepared patient is always more successful with testing.”

Ms. Smith says that when training other technicians, she teaches that if there are six fixation losses or more, the test must be restarted. She says that bad results are a waste of both the patient’s and the doctor’s time.

Dr. Brubaker adds that when the technician is able to stay engaged with the patient, they can reduce false positives.

“Techs learn to recognize when someone is not doing well on the test or maybe even falling asleep,” he says. “A good visual field tech can truly make or break a treatment plan so it’s important that they recognize how valuable their role is. It’s shifting the mindset from thinking it’s something ‘I’m stuck doing,’ to recognizing the critical role they play in glaucoma management.”

Structural tips for techs

The same diligence and attention are important for structural testing. It’s equally important that techs understand the value of their role in administering the tests.

Dr. Brubaker says that a good starting point with an OCT test is making sure the signal strength is appropriate—a 7 or higher.

“Also, making sure that there are no artifacts like blinking and that everything is lined up with the nerve,” he says. “Doctors can only make good decisions on good scans.”

Ms. Paulson says the best tip for structural testing is understanding the limiting factors. Does the patient have cataracts? Is there a retinal issue that is keeping the patient from focusing on the right spot?

“These issues can impact the measurements, so you have to be aware of them,” she adds.

Ms. Smith agrees.

“A lot of it is troubleshooting,” she says. “If a tech is getting a poor-quality scan but did everything right, we go back to the diagnosis. If there is a thick cataract, it’s going to impact the signal strength. We may have to have the patient avoid looking directly at the light. It’s about being a critical thinker.”

There are also opportunities for technicians to hone their skills, says Ms. Paulson.

“I think the best thing that techs can do to improve their testing is to learn from mistakes,” she sums up. “Take the initiative to ask the doctor what they see in your measurements and if there are areas that you can improve.” OP