Diabetic retinopathy (DR) is growing in prevalence — it affected an estimated 9.6 million people in the US in 2021, with nearly 2 million already in the vision-threatening stage (1). The pressure to identify and manage risk efficiently is increasing, but the debate about how best to achieve this is ongoing.
One test that is becoming more routinely used in clinics is electroretinography (ERG). However, when I speak with colleagues about incorporating ERG into DR management, a common concern arises: “Will this slow down my clinic?” That concern reflects reality a decade ago when ERG systems were larger and more technically demanding, whereas current handheld ERG devices are designed for efficiency. These modern tests typically take only a few minutes, can be delegated to staff, and do not require dilation. Moreover, in most cases these testing protocols integrate into clinic flow without any significant disruption.
Objective evidence for the patient
What makes ERG so powerful is its ability to detect functional changes in the retina that often precede structural ones (1, 2, 3, 4). Just as we track early cardiac biomarkers to prevent heart attacks, we need to embrace early functional markers in the eye, and ERG is ideally suited to play that role. It complements optical coherence tomography (OCT) and fundus imaging, especially in the preclinical stages when structural signs may be subtle or completely absent (1).
Fluorescein angiography (FA) might show peripheral nonperfusion at a certain stage, but before those vascular changes become apparent, ERG can provide an early signal that offers us an opportunity to intervene. In situations where the necessity of FA is uncertain, ERG can provide additional information that supports our decision-making. Because it is non-invasive and relatively quick to perform, ERG may help determine whether FA is immediately warranted, or whether it can be deferred. In this way, ERG does not replace FA, but rather complements it by refining the timing and context in which dye-based studies are pursued. For example, if a patient with a long-term diabetes history comes in without hemorrhages or microaneurysms but shows functional decline on ERG, that may be the pivotal moment to emphasize better systemic control. It gives patients tangible information — objective evidence that their retina is changing even if their vision seems fine for now.
I was pleased to see this sentiment supported in a recent longitudinal prospective study published in Ophthalmology Science (1). The study evaluated 56 parameters from four testing modalities — ERG, ultra-widefield fluorescein angiography (UWF-FA), optical coherence tomography angiography (OCTA), and fundus photography (FP) — to determine which modality best predicted progression to vision-threatening complications (VTC) such as proliferative DR, diabetic macular edema (DME), or the need for treatment.
What stood out most was that the RETeval DR Score, derived from ERG and pupillometry, emerged as the single strongest predictor of progression. A DR Score of 26.9 was associated with a relative risk of 5.6 for developing VTC (p < 0.0001). That’s higher than any of the structural parameters evaluated. While these structural imaging parameters also showed statistical significance, their predictive power was lower. The best predictive parameters from UWF-FA, OCTA and FP were:
● UWF-FA total ischemia index ≥ 0.125: RR = 5.3 (p < 0.0001)
● OCTA foveal avascular zone (FAZ) area ≥ 0.295 mm²: RR = 3.6 (p < 0.05)
● Fundus photograph–based DRSS ≥ 47: RR = 2.1 (p < 0.05)
It’s also important to note that ERG is now included in the American Academy of Ophthalmology’s Preferred Practice Pattern® Guidelines for Diabetic Retinopathy (1). These guidelines are the benchmark for evidence-based care, and their acknowledgment of ERG reflects a growing consensus that functional testing should be part of comprehensive DR assessment.
Information we can act upon
In my clinical practice and research, I’ve always been driven by a simple goal: to identify risk earlier so we can intervene sooner and preserve vision. For many years we’ve relied almost exclusively on structural findings to guide DR management, but structure alone doesn’t tell the whole story. When fundus signs are already advanced, we’ve missed our chance to intervene proactively. The sweet spot for ERG is earlier — when it can serve as a wake-up call and a guide for tailored follow-up.
In terms of risk stratification, ERG gives us a way to personalize follow-up intervals. Imagine two patients with mild or moderate nonproliferative diabetic retinopathy (NPDR). If one shows completely normal full-field ERG results, I may feel comfortable extending their next visit out to 18 months. But if the other shows marked functional deficits, I’d likely bring them back in six months. The functional data guides my decisions in a way that fundus appearance alone cannot.
This is a significant advancement that has practical implications not only for retina specialists like myself, but also for general ophthalmologists and optometrists. For optometrists, it offers a reliable and efficient way to identify patients who may need earlier referral. For general ophthalmologists, it supports more informed decisions about when to monitor and when to treat. And in retina clinics, ERG can help triage patients more accurately and explain prognosis more clearly. When a single, objective number can provide that kind of predictive clarity, it’s a tool worth paying attention to.
A turning point in diabetic eye care
We’ve learned from other chronic disease specialties — cardiology, nephrology, endocrinology — that early intervention matters. The same holds true for DR. Yet we still often wait until structural damage becomes visible before we act; that’s a missed opportunity. As a retina specialist involved in the DRCR Retina Network and the Mary Tyler Moore Vision Initiative, I’ve spent years exploring how we can improve outcomes for DR patients. One technology starting to stand out — particularly for its potential to reshape how we evaluate, stratify, and motivate patients — is electroretinography (ERG).
As these devices are placed in more clinics and as we begin testing ERG as part of the Mary Tyler Moore Vision Initiative, I hope we’ll see a shift in how we think about diabetic eye care. ERG may not have been part of standard DR care a decade ago, but the data — and our clinical experience — are catching up fast. It’s time to re-assess our protocols. It’s not just about managing damage — it’s about anticipating it. With the right tools, we can detect risk earlier, intervene more wisely, and perhaps even change the course of this disease.
Integrating ERG Into Workflow and Patient Conversations
In most practices, ERG can be performed during a standard visit without adding major logistical steps. The data may help clarify whether additional testing, such as FA, is required immediately or can be deferred.
ERG also offers a way to engage patients in discussions about their disease. By presenting an objective measure of retinal function, clinicians can frame conversations around risk and disease progression in a way that is understood by patients. This can encourage patients to take a more active role in managing both systemic and ocular health.
References
- EA Lundeen et al., “Prevalence of Diabetic Retinopathy in the US in 2021,” JAMA Ophthalmol., 141, 747 (2023). PMID: 37318810.
- D Ratra et al., “Early structural and functional neurovascular changes in the retina in the prediabetic stage,” Eye (Lond), 35, 858 (2021). PMID: 32461566.
- EJ Duh et al., “Diabetic retinopathy: current understanding, mechanisms, and treatment strategies,” JCI Insight, 2, 14 (2017). PMID: 28724805.
- JJ McAnany et al., “Clinical electroretinography in diabetic retinopathy: a review,” Surv Ophthalmol., 67, 712 (2022). PMID: 34487740.
- M Brigell et al., “Predictive Value of ERG, OCT-A, and UWF-FA in Patients with Diabetic Retinopathy,” Invest Ophthalmol Vis Sci., 61, 4038 (2020).
