Visual Electrophysiology

Visual electrophysiology encompasses a variety of specialized tests used to assess the function of your eyes and the visual pathways to your brain. These tests are especially helpful when other diagnostic methods cannot determine the cause of vision problems.

At Bascom Palmer Eye Institute, part of the University of Miami Health System, we offer the following visual electrophysiology tests:

Types of Tests

Full-field Electroretinogram (ffERG): Measures the electrical activity of all retinal cells in response to light flashes.

Multifocal Electroretinogram (mfERG): Assesses local electrical activity in the central retina.

Visual Evoked Potentials (VEP): Measures the brain’s response to visual stimuli:

SWEEP Visual Evoked Potentials (SWEEP VEP): Objectively assesses vision in pre-verbal or non-verbal children using varying sizes of checkerboards.

Electrooculogram (EOG): Evaluates the outer retinal cells and retinal pigment epithelium function.

Contrast Sensitivity Function (CSF): Tests the ability to detect differences in light and dark.

Farnsworth Color Tests: Measures color vision:

Preferential Looking Techniques (PLT): Measures vision in children or patients who cannot verbally respond.

What to Expect

Duration

15–90 minutes, depending on the test and patient needs.

Outpatient

Most tests allow you to go home the same day.

Eye Dilation

Some tests require dilating your pupils with eye drops.

Sedation or Anesthesia

Infants and young children may need sedation or general anesthesia for certain tests.

Preparation

Bring your glasses and sunglasses. Some tests may cause temporary light sensitivity.

Your ophthalmologist will explain which specific test is best for your condition.

Who Should Consider Visual Electrophysiology?

Patients with unclear vision problems that other tests cannot diagnose

Young children or non-verbal patients who cannot provide feedback about what they see

Why Choose Bascom Palmer Eye Institute?

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FAQ

What is visual electrophysiology, and how does it help diagnose eye problems?

Visual electrophysiology uses gentle electrical recordings to gauge how well your retina and optic nerve respond to light patterns, like a brainwave test for the visual system—think EKG but for sight. Tests like ERG (electroretinogram) detect retinal cell health in diseases like RP, while VEP (visual evoked potential) flags nerve delays in MS. It’s objective, bypassing subjective complaints, ideal for kids or unexplained losses.

Why might a doctor order these tests over a standard eye exam?

When routine checks miss subtle dysfunction—e.g., normal acuity but poor night vision—they quantify electrical signals, pinpointing if the issue is retinal (low ERG waves) or post-retinal (delayed VEP peaks). Useful for genetic counseling or trial eligibility, they’re non-invasive gold standards, especially pre-surgery, ensuring treatments hit the right target without guesswork.

What happens during a visual electrophysiology session?

You’re seated comfortably, eyes dilated if needed, viewing flashes or checkerboard patterns on a screen—electrodes on scalp, skin near eyes, or contact lenses capture responses, all painless like a mild tickle. Sessions last 30-90 minutes, with breaks; no prep beyond avoiding caffeine. Results plot waveforms instantly, demystifying why vision falters.

What do abnormal results indicate, and what's next?

Wavy ERG might signal cone-rod dystrophy, needing low-vision aids; sluggish VEP suggests demyelination, prompting MRI. Normal? Reassures, ruling out neuropathy. Follow-up: tailored plans, from vitamins to gene therapy—data-driven, it empowers precise paths, often catching progression early.

Are these tests safe for all ages, and how often are they repeated?

Absolutely—zero radiation, suitable for infants (with sedation if wiggly) to seniors. Rare side effects like brief flashes post-test fade quick. Repeat annually for progressives like Stargardt, or as-needed for monitoring meds; they’re a snapshot, evolving with tech like multifocal ERG for macular detail.