An Electroretinography (ERG) is a vital diagnostic tool used to assess the health of your retina, the light-sensitive tissue at the back of your eye. This non-invasive test measures how well your retinal cells respond to light. Our specialists at Pristine Eye Hospitals use ERG to gain critical insights into your retinal function.
What is a Electroretinography (ERG)?
Think of an ERG as an “EKG for your eye.” It records the electrical signals generated by the retina’s cells, specifically the photoreceptors (rods and cones), in response to flashes of light. By analyzing the strength and timing of these electrical responses, our neuro-ophthalmologists can objectively evaluate the health of your entire retina and identify specific areas of dysfunction that may not be visible during a standard eye exam.
Why is this test performed?
This test is crucial for:
Diagnosing inherited retinal diseases like retinitis pigmentosa and cone-rod dystrophy.
Investigating unexplained vision loss, night blindness, or loss of peripheral vision when the eye appears structurally normal.
Evaluating retinal function before certain types of eye surgery.
Monitoring for potential retinal toxicity from certain long-term medications.
How to Prepare for Your Electroretinography (ERG)
Preparing for your ERG is simple and helps ensure accurate results. Your pupils will be dilated, so your vision will be blurry and sensitive to light for several hours afterward. We recommend you:
Arrange for someone to drive you home after the appointment.
Bring a pair of dark sunglasses to wear for comfort post-test.
Avoid wearing eye makeup, face creams, or lotions on the day of your test.
The Procedure: What to Expect Step-by-Step
1. First, we will administer eye drops to numb your eye and dilate your pupil. This can take about 20-30 minutes to take full effect.
2. You will then be seated in a dark room to allow your eyes to adapt. A tiny, specialized sensor (either a fine thread or a contact lens) will be gently placed on the surface of your eye to record the electrical signals.
3. You will be asked to look at a screen that produces a series of controlled light flashes, varying in brightness and colour. Your only task is to relax and stare at the light as directed.
4. The sensor records your retina’s responses, which are displayed as waveforms on a monitor for our specialist to analyze. The entire recording process typically takes 30 to 45 minutes.
Understanding Your Results
The ERG produces a series of waveforms that represent the electrical activity of different retinal cells. A healthy retina generates a predictable pattern. Deviations from this normal pattern—such as a reduced or delayed response—can indicate specific types of retinal disease or damage.
Your neuro-ophthalmologist at Pristine Eye Hospitals will meticulously analyze these waveforms. They will then correlate the findings with your symptoms and other clinical examinations to provide an accurate diagnosis and develop a personalized treatment plan.
Frequently Asked Questions
Is the ERG test painful?
The test is not painful. We use numbing eye drops to ensure you are completely comfortable, and you may only feel a light sensation from the sensor on your eye’s surface.
How long does an ERG test take?
The entire appointment, including pupil dilation and dark adaptation, typically lasts about 60 to 90 minutes. The actual recording portion of the test is shorter.
Are there any side effects from an ERG?
Side effects are rare and minor. You may experience temporary blurry vision and light sensitivity from the dilating drops, and your eye might feel slightly scratchy or watery for a short time.