Electroretinography (ERG), with interpretation and report; full field (ie, ffERG, flash ERG, Ganzfeld ERG)
CPT4 code
Name of the Procedure:
Electroretinography (ERG); also known as full field ERG, flash ERG, or Ganzfeld ERG.
Summary
Electroretinography (ERG) is a diagnostic test that measures the electrical activity of the retina in response to light. This test evaluates the function of the retina, including its rods and cones, which are crucial for vision.
Purpose
The ERG is used to diagnose and monitor various retinal conditions, such as retinitis pigmentosa, cone-rod dystrophy, and other inherited retinal degenerations. It helps determine the severity and progression of retinal diseases and informs treatment decisions.
Indications
- Unexplained vision loss
- Inherited retinal diseases
- Retinal detachment
- Diabetic retinopathy
- Drug toxicity effects on the retina (e.g., from chloroquine or hydroxychloroquine)
- Night blindness or other vision problems in low light
Preparation
- Patients may be instructed to avoid caffeine for at least several hours before the test.
- Contact lens wearers should bring their lenses and case to remove them before the test.
- Pupils may be dilated using medicated eye drops, so patients should arrange for transportation as vision may be blurry post-procedure.
Procedure Description
- The patient sits in a dark room to adapt for around 20-30 minutes.
- Anesthetic eye drops are applied to numb the eyes.
- Special contact lenses with embedded electrodes are placed on the eyes.
- The patient will look at a series of flashing lights of varying intensities and colors.
- The electrodes record the retinal electrical responses to these light stimuli.
- The recordings are analyzed to assess the function of the retinal cells.
Duration
The procedure typically takes about 1 to 2 hours, including preparation and dark adaptation time.
Setting
The ERG is usually performed in a specialized ophthalmology or optometry clinic or an outpatient diagnostic center.
Personnel
The test is administered by a trained ophthalmic technician or optometrist. An ophthalmologist interprets the results.
Risks and Complications
- Mild, temporary discomfort from the contact lenses and eye drops.
- Rarely, allergic reactions to the eye drops.
- Temporary blurry vision from dilating drops.
Benefits
- Accurate diagnosis of retinal conditions.
- Helps monitor disease progression and treatment efficacy.
- Can guide clinical management and improve patient outcomes.
Recovery
- Vision may be blurry and light-sensitive for a few hours due to dilating drops.
- Patients are typically instructed to avoid driving immediately after the test.
- Normal activities can generally be resumed shortly after.
Alternatives
Other diagnostic tests like Optical Coherence Tomography (OCT) or Visual Field Testing may be used depending on the condition. Each test has its unique strengths and limitations, which an ophthalmologist can explain based on specific patient needs.
Patient Experience
Patients may experience mild discomfort from the contact lenses and bright lights but should not feel pain. Numbing drops help minimize discomfort. Post-procedure, light sensitivity and blurred vision due to pupil dilation are common but temporary.