Study: PERG testing valuable for glaucoma management

William Sponsel, MD, discusses the findings.

A recent study in Current Ophthalmology Reports by Porciatti and Ventura found that pattern electroretinography (PERG) testing shows a strong correlation with functional loss secondary to glaucoma. Below is a discussion of PERG and the study results with William Sponsel, MD, of San Antonio, Texas.

Ophthalmology Management: What is your experience with PERG?

William Sponsel, MD: I began working with electrophysiology in glaucoma patients over 30 years ago in my clinical laboratory in Wisconsin, as one of Paul Kaufman’s fellows. I helped compile book chapters on the, by then, obvious utility of PERG and visual evoked potential (VEP) in the diagnosis and management of all forms of glaucoma. Dynamic functional information that could never be extracted from visual field or imaging studies could give us an immediate impression of the physiologic wellbeing of the ganglion cells and associated visual pathway.

OM: How does PERG fit into your practice in terms of patient selection and when/how often to use it?

WS: We have extensive clinical experience with both PERG and VEP in glaucomatous eyes using the Diopsys system. PERG tends to be abnormal in both eyes of patients with progressive glaucomatous neurodegeneration. Particularly spectacular PERG responses to therapy are seen in patients with intermittent angle closure glaucoma after laser iridotomy. This reaffirms the extensive literature showing a very strong relationship between IOP-induced ganglion cell compromise and reduction in PERG magnitude. Unlike the more static information provided by other tools, PERG immediately identities extant and current dynamic functional compromise.

OM: Why are the findings of this latest study significant?

WS: The recent review by Porciatti et al is an up-to-date objective compilation of PERG’s utility in glaucoma management. PERG provides dynamic information that cannot be gleaned via perimetry or OCT, alone or together, without allowing for the destruction of tens of thousands of axons to confirm a clinical trend over a period of many months.

OM: Do you see study results like this altering CMS’s plans of whether to reimburse for PERG when used for glaucoma evaluations?

WS: I am confident that, eventually, the strong scientific evidence for the use of PERG and VEP in managing glaucomatous neurodegeneration will prevail.

I am sympathetic with those in authority who have the onerous responsibility to reign in the widespread overuse of recently introduced clinical diagnostic and therapeutic methods. While this is a two-sided problem, the clinician’s perspective would emphasize that the abusers are in the extreme minority and offenders can be readily identified. Withholding reimbursement for the only objective integrated tests of ocular and CNS function cannot reasonably prevail.

I thus remain optimistic for the integration of clinical electrophysiology into our current paradigm of glaucoma management, primarily because of the clinical evidence for its efficacy and utility.

OM: Is there any other stage in the disease (glaucoma) that neuroprotection can be achieved, or is it only in the earliest stage before there is permanent loss to structural or perimetry? Are we missing the opportunity for early neuroprotection without PERG?

WS: This is the area that particularly raises my enthusiasm for the practical integration of clinical electrophysiology into day-to-day glaucoma management. As we observe patient responses, we immediately appreciate the importance of IOP oriented therapy in certain patients, and the need for different approaches in others. Clinical electrophysiology can help obviate the unnecessary overtreatment of trivial ocular hypertension. Clinical electrophysiology can help delineate patients with mild disease at high risk of rapid progression from patients with stabilized advanced disease at minimal risk of progression.

Integrated study of PERG, VEP, visual field and OCT data in a very large patient cohort has recently confirmed that PERG tends to be nearly equally compromised in both eyes of POAG eyes, but that the VEP shows a stunning inverse association between high- and low-contrast latencies between the paired eyes. This has essentially proven that the brain can glean high-speed, low-resolution visual information from one eye and low-speed, high-resolution information from the other eye when neither eye can provide both simultaneously. This means clinicians can now use the combined PERG/VEP data from the same device at the same visit to determine how efficiently the brain is compensating for bilateral disease. The importance of this insight to enhance quality of life for patients with glaucoma and age-related neurodegeneration processes cannot be overemphasized. OM

Tele-ophthalmology brings eye care to remote patients

Speakers at conference discuss telemedicine’s impact on underserved communities.

By Robert Stoneback, associate editor

Columbia University Medical Center recently hosted a Tele-Ophthalmology and Artificial Intelligence conference at its Edward S. Harkness Eye Institute, featuring discussion on how tele-ophthalmology can help improve patient care in the communities that will need it most.

DIABETIC RETINOPATHY SCREENINGS

Among the speakers was Seema Garg, MD, PhD, associate professor of ophthalmology at North Carolina’s UNC School of Medicine.

Dr. Garg helped establish the North Carolina Diabetic Retinopathy Telemedicine Network, following a 2012 pilot study she coauthored and had published by JAMA.

That study found diabetic retinopathy (DR) screening rates among patients at a University of North Carolina clinic increased from 32% to 71% over the course of the year, once remote DR screenings became available at that clinic.

A 2017 JAMA study that Dr. Garg coauthored evaluated the effectiveness of the North Carolina Diabetic Retinopathy Telemedicine Network in the state’s rural and underserved communities. The mean rate of screening for DR was initially 25.6%, but this increased to 40.4% after implementation of the telemedicine program.

Dr. Garg noted the numerous hurdles to traditional patient screenings in underserved communities, including poor healthcare access and the time and cost associated with office visits. “We have to be able to harness technology to solve this public health problem,” she said.

Jonathan Myers, MD, chief of glaucoma services at Philadelphia’s Wills Eye Hospital, discussed similar research performed by his hospital.

The Philadelphia Glaucoma Detection and Treatment Project, conducted by Wills Eye, screened 906 subjects in underserved Philadelphia communities. They were given vision screenings and exams at primary-care offices throughout the city. Results of these screenings and exams were shared via telemedicine with ophthalmologists, who sent back results in five days. An automated letter with the results was also sent to the patient’s primary-care doctor to keep him or her involved. The telemedicine system detected eye health issues with about 80% accuracy, said Dr. Myers, and discovered a “significant amount” of treatable DR.

The cost of each screening was roughly $10, Dr. Myers said; this price did not take into account project expenses, such as equipment and man power, he added.
 

GLOBECHEK

William Mallon, MD, CEO of GlobeChek, said that, while many of his colleagues fear tele-ophthalmology will cost them patients and revenue, they should embrace the technology.

The GlobeChek standalone kiosk can complete an eye scan in about seven minutes. The kiosks, which are currently being researched at Columbia University, are designed to be placed in high-traffic areas, such as airports or shopping malls. Patients who use the kiosk receive an e-mailed report on their eyes, along with a referral to a local physician. The report contains information including IOP, OCT and retina and optic nerves photos.

Dr. Mallon says that, given the potential for shortages in ophthalmology, “we need to be smarter about how we practice.” Outreach will be a big component to this approach, and “managing these chronic patients outside of our offices will improve the efficiency of what we do in the office,” he said.

Patients with chronic conditions can use GlobeChek to send a quick update to their physicians about the condition of their eyes, said Dr. Mallon. Then, the physician can decide if a further appointment is needed. OM