Optopol Technology developed the Optopol PTS 2000 with Zippy Estimation Thresholding Algorithm (ZETA) software to allow for faster threshold visual field testing.

“Prior to perimeter manufacturers developing this type of algorithm, threshold testing for such a detailed functional test could take more than 5 to 10 minutes per eye,” says Bob Padula, MBA, president of Optopol USA. “The quality of a patient’s response is known to decline with longer tests in some patients. Visual field testing is particularly difficult for older populations in terms of staying attentive and maintaining their posture and alignment.”

The Optopol PTS 2000 offers 3 ZETA strategies for multiple threshold test patterns, including ZETA Standard, ZETA Fast, and ZETA Faster. “All 3 types are faster threshold testing algorithms than previous generation strategies; the difference being the number of steps used to determine a result, decreasing testing time without sacrificing data reliability,” Padula says.

David Fleischman, MD, MS, FACS, associate professor in the department of ophthalmology at University of North Carolina in Chapel Hill, who was a principal investigator for ZETA Fast’s sponsored investigation,¹ used primary open angle glaucoma (POAG) patient and non-POAG controls to compare perimetric devices. “ZETA Fast did a better job of picking up more negative mean deviation values and higher pattern standard deviation values in glaucomatous patients,” he says. “Therefore, the Optopol perimeter was better at discriminating between control and glaucomatous subjects.”

Padula says that most Optopol users prefer ZETA Fast because it’s a good balance between reliability checks performed and shorter test times. “Using a 24-2 test pattern, ZETA Fast takes between 2.5 and 4.5 minutes per eye, depending on the patient,” he says. “This cuts the testing time in half, without sacrificing the quality of results.”

Dr. Fleischman says patients are rarely fans of visual field exams. “But these tests are so important because they serve as key indices for determining if surgery is needed and its success or failure,” he says.

Ilan Hartstein, MD, an ophthalmologist at La Palma Eye Care Center, purchased the Optopol PTS 2000 because he was looking for a device that was modular in nature so the screen, central processing unit, printer, and bowl were all separate components. “This makes it easier to set up, streamlines maintenance, and decreases overall costs,” he says.

Innovative Advancements

ZETA's algorithm uses Bayesian probability theory and probability density functions built from age-normative data sets. ZETA Standard testing better identifies accidental invalid responses, which in turn leads to fewer nonspecific defects in a healthy visual field.¹ “Each location threshold is crossed at least once and the final estimate is set at a probability function’s peak, closer to the patient’s real threshold,” Dr. Fleishman says.

ZETA Fast is a shorter test that requires at least 1 positive response to calculate the final threshold estimate, leading to high sensitivity in detecting real defects, Dr. Fleishman says. A typical test in a normal patient lasts around 2.5 minutes per eye, and in a glaucomatous patient approximately 4.5 minutes.

The Optopol PTS 2000 has many advantages over similar products, Dr. Hartstein says. “Because it’s a Microsoft Windows–based device, it’s easy to connect online to receive upgrades and technical support,” he says. “You can perform visual field testing with various testing algorithms and view printouts in a variety of formats. There’s a lot of flexibility in testing parameters and you can easily modify it to fit your practice’s needs.”

According to Dr. Fleischman, the unit and interface are dynamic and adaptable. “The machine has an elegant blink control mechanism and eye tracker to ensure the greatest chance of success for each test,” he says. “The device and its recorded data are easy to work with for research purposes.”

Clinical Applications

ZETA Fast’s perimeter is appropriate for following and diagnosing optic neuropathies, central nervous system–related visual field loss, and retinopathies. “The driver’s visual field test is easily performed on this perimeter,” Dr. Fleischman says.

Dr. Hartstein’s practice is 60% glaucoma, and those patients are tested annually on the Optopol PTS 2000. His go-to test for glaucoma patients is the 24-2 pattern using the ZETA Fast strategy. He will also use ZETA Faster in less-nuanced situations such as performing routine glaucoma visual field testing in patients with relatively normal fields and no optic nerve or intraocular pressure changes. He will also use ZETA Faster in patients who can’t tolerate longer testing for various reasons.

Dr. Fleischman prefers ZETA Faster, even though it may not produce the purity of data that the standard or even the fast algorithm can deliver. “The faster the test, the happier the patient,” he says. “The happier the patient, the more often they will produce results. And make no mistakes, these are still excellent data.” GP

Reference

1. Mathews B, Laux J, Barnhart C, Fleischman D. Comparison of ZETA Fast (PTS) (Optopol Technology) and Humphrey SITA Fast (SFA) (Carl Zeiss Meditec) perimetric strategies. J Ophthalmol. 2022;2022:5675793. doi:10.1155/2022/5675793