Diopsys’ patented device overcomes eye-contact problem with a noninvasive sensor.

Visual electrophysiology has been used for sometime for the diagnosis and management of many vision disorders, but was restricted to hospital use. The reason: previous generations of sensors necessitated contact with the eye. They even were capable of harming the eye.

“Even in the hands of the most skilled technician, there is the possibility of a corneal abrasion using invasive electrodes, although they are rare,” says Alberto Gonzalez Garcia, MD, a neuro-ophthalmologist and research director at Diopsys, Inc.

But Diopsys, with its ERG unit and lid sensor, allows for the migration of this procedure from tertiary care to office-based, community care.

A NONINVASIVE APPROACH

The key difference between other visual electrophysiology platforms and the Diopsys ERG is its noninvasive sensors, which eliminate the need for direct contact with the eye. They also eliminate the need to administer anaesthetic eye drops. “With a lack of contact [to the eye], patients are more cooperative,” says Dr. Gonzalez of the patented Diopsys ERG lid sensor.

Richard Tipperman, MD, a partner with Ophthalmic Partners in Bala Cynwyd, Pa., and an attending surgeon at Wills Eye Hospital in Philadelphia, discussed other advantages. “This is very practical for [community] ophthalmologists. The contact lens that patients had to wear [previous to the availability of the Diopsys ERG lid sensor] was cumbersome for patients.”

ACCURACY IN THE OFFICE

The noncontact sensors are very thin — so thin that they do not come into contact with facial muscles like skin electrodes on other visual electrophysiology devices. When such contact occurs, it could interfere with reaching accurate results. Another advantage to Diopsys’ advancement in sensor technology means that staff members have an easier time, and are more consistent, with placing the electrodes on the patient.

“The beauty of this is that it is in-office testing,” said Mitchell Jackson, MD, founder and CEO of Jacksoneye and a clinical assistant at the University of Chicago Hospital. “You just have to know how to put the lid strips on. It is not operator-dependent.”

This latest Diopsys platform also expands a clinical practice’s diagnostic capabilities, says Dr. Gonzalez.

“Visual electrophysiology is not just for the management of rare diseases, but also for common diseases like glaucoma, macular degeneration and diabetic retinopathy,” he says.

OBJECTIVE RESULTS

Whereas the visual field (VF) test supplies information subjectively,¹ ERG obtains information about function in an objective way that can inform treatment decisions earlier, says Dr. Jackson. The pattern ERG, for example, records the retinal ganglion cell signal in response to pattern stimuli, and flicker ERG records the retinal signal in response to flash stimuli of high frequency.

“You are not relying on subjective responses by the patient,” says Dr. Jackson. “The pattern ERG will tell you if the ganglion cells are impaired. As a result, we are catching disease at an earlier state.”

According to the Diopsys website, the physician can obtain color-coded reports regarding the test’s findings, minimizing subjectivity.

INSIGHTS

Pattern ERG and flicker ERG look at progression of disease as well as recovery of the disease process once treatment is implemented. Thus, ERG testing could provide insights for clinicians who are looking for conditions that secondarily affect vision, such as hydroxychloroquine retinopathy, caused by (Plaquenil, AvKARE).

“If a patient takes enough Plaquenil over his or her life, he or she is at risk of developing a maculopathy,” says Dr. Tipperman. “You can do VF testing, but ERG testing will pick up Plaquenil retinopathy before other tests will.”

Dr. Tipperman says that the test is more sensitive than a VF test in identifying glaucoma suspects who are at risk and should be treated. A percentage of the patients in a standard comprehensive ophthalmology practice will have relatively normal VF but should they take the ERG test they will show evidence of functional damage, he explains.

Clinicians are not left to evaluate the findings of either the pattern ERG or flicker ERG on their own, thanks to the platform’s software.

A drawback of the technology is that not every patient will be able to undergo pattern ERG or flicker ERG. Patients who experience seizures, for example, who cannot stay still while seated would not be candidates for either test. OM

REFERENCE

1. Chew SS, Kerr NM, Wong AB, et al. Anxiety in visual field testing. Br J Ophthalmol. 2016 Aug;100:1128-1133.

Dr. Jackson is a consultant to Diopsys and Dr. Tipperman is a speaker for Diopsys.