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Ophthalmology Spotlight: How Patients Benefit from ERG Vision Testing

Posted by Diopsys, Inc. on March 29, 2018 at 8:49 AM

An Interview with William I. Bond, MD, FACS:

After over 40 years in practice, William I. Bond, MD has gotten fairly confident in his ability to evaluate a patient in the clinic and understand the health of the eye. 

The kind of knowledge that only comes from interacting with patients of all ages and vision disorders daily is a valuable tool when working with a new vision loss patient. It is what helps Dr. Bond look at a patient with a cataract, for example, and have an awareness that something else might be going on, perhaps something unseen that is affecting one or more parts of the complex human visual system. It may be that the degree of refractive change a patient is experiencing is more profound than what is suggested by the stage of the cataract. Yet, what that “something else” might be is not always obvious.


Wisdom and Diagnostics in Ophthalmology

In other cases, the wisdom of years might lead a skilled clinician like Dr. Bond to direct his or her attention to a specific part of the eye based on other findings. A microaneurysm on the retina suggests a range of possibilities for the differential diagnosis. But like most clinical findings, a microaneurysm is also not pathognomonic, and it requires further directed investigation to understand exactly what is going on inside the eye. 

Even for the most experienced clinicians, then, there are times when the most thorough clinical examination is inconclusive and when even the best information gathering exercise winds up incomplete. And when it comes to diseases of the human eye, a missed diagnosis might mean the eventual loss of visual ability.

It is these types of scenarios—when there is suspected retinal pathology but no clear indication of what is going at the back of the eye—that call for the use of directed diagnostic testing. Knowledge is power, and gathering additional information might help save a patient's vision. 

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Objective Retinal Testing

That is why, when Dr. Bond suspects there might be retinal pathology of unknown cause or when his clinical findings are inconclusive, he turns to his electroretinography (ERG) device to help understand the health of the retina. As an objective measure of electrical responses within the retina, ERG is crucial for understanding how the retina is functioning, with multiple applications across the continuum of care.

“The important thing about ERG is that it is not disease specific. You don’t use it just for the patient in whom you suspect diabetic retinopathy, glaucoma, or CRVO. Certainly those are three disease states where there is a mountain of evidence to support its use, but because it’s an objective measure of retinal function, ERG is really useful for building a differential diagnosis in patients with confounding or conflicting clinical findings and those with unexplained visual changes,” Dr. Bond said.

According to Dr. Bond, ERG can help stage disease, in terms of correlation of retinal function with other clinical parameters,1-6 and gauge response to treatment, in terms of how the ERG signal changes over time while the patient is being treated – both tracking progression and improvement.7 That information is additive to the clinical impression for prognostic purposes, and, equally as important, for deciding when and if to initiate appropriate treatment, how aggressively to treat, and whether or not additional treatment is likely to have a benefit.

Dr. Bond uses a specific type of ERG called flicker (a step of the standard ISCEV full field ERG that flashes at ≥ 30Hz) with his cataract patients, as it is a viable testing modality even in the presence of media opacities.8

“Dense cataracts can make it difficult to look at and determine the health of the retina. That can have a couple of implications. For one, you could end up with a postoperative visual surprise if there is an undiscovered retina disease. As well, if you are thinking about using premium lens technologies, you want to make sure the macula is healthy enough to support the proposed viewing system. What you can’t see can really affect the outcome,” Dr. Bond said.


CONCLUSION:

In truth, no diagnostic tool, no matter how good or how accurate it is, will ever replace the human evaluator. Instead, like most technology that has been integrated into modern life, advanced diagnostic equipment is meant to help the eye care clinician better appreciate what he or she cannot see or determine alone. 

According to Dr. Bond, the potential applications of ERG for ophthalmology are myriad, precisely because test results

  • improve the diagnosis of patients with conflicting clinical findings,
  • aid in tracking treatment efficacy,
  • help manage patient expectations, and
  • lower the risk of postoperative surprises.

More often than not, it helps in figuring out what that “something else” might be so it can be addressed and managed appropriately.

“ERG  testing has allowed me and many other eye care providers improve outcomes for our patients. That's why I do what I do. It's all about the patient,” Dr. Bond said.


Ask if Diopsys VEP or ERG vision testing may fit your practice

1. Bresnick GH, Palta M. Temporal aspects of the electroretinogram in diabetic retinopathy. Arch Ophthalmol. 1987;105:660-664. 2. Holopigian K, Greenstein VC, Seiple W, Hood DC, Carr RE. Evidence for photoreceptor changes in patients with diabetic retinopathy. Invest Ophthalmol Vis Sci. 1997;38:2355-65. 3. Kim SH, Lee SH, Bae JY, Cho JH, Kang YS. Electroretinographic evaluation in adult diabetics. Doc Ophthalmol. 1997-1998;94:201-13. 4. Pescosolido N, Barbato A, Stefanucci A, Buomprisco G. Role of Electrophysiology in the Early Diagnosis and Follow-Up of Diabetic Retinopathy. J Diabetes Res;2015:319692. 5. Tzekov R, Arden GB. The Electroretinogram in Diabetic Retinopathy. Surv Ophthalmol 1999, 44:53-60. 6. Banitt MR, Ventura LM, Feuer WJ, et al. Progressive loss of retinal ganglion cell function precedes structural loss by several years in glaucoma suspects. Invest Ophthalmol & Vis Sci 2013;2346-2352. 7. Holm K, Schroeder M, Lövestam Adrian M. Peripheral retinal function assessed with 30-Hz flicker seems to improve after treatment with Lucentis in patients with diabetic macular oedema. Doc Ophthalmol. 2015;131:43-51. 8. Foerster MH, Li XX. Evaluation of the central retina and optic nerve function in media opacities. Doc Ophthalmol. 1986;63:101-6.

Topics: Pattern ERG, Flicker ERG

Modern Visual Electrophysiology

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As the world leader in modern visual electrophysiology, Diopsys, Inc. has done more than any other company to advance the use of ERG and VEP in the eye care practice. Read through our blog to gain valuable insights into the benefits and integration of this valuable technology.

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