Name of the Procedure:

Electroretinography (ERG); Multifocal Electroretinography (mfERG)

Summary

Electroretinography (ERG) measures the electrical responses of various cell types in the retina, including the photoreceptors (rods and cones), inner retinal cells, and the ganglion cells. The multifocal ERG (mfERG) is a more specialized test that maps the central retinal function to help diagnose and monitor diseases involving the macula (central part of the retina).

Purpose

The procedure is used to evaluate the function of the retina, particularly the macula. It helps in diagnosing retinal conditions like retinitis pigmentosa, age-related macular degeneration, diabetic retinopathy, and other retinal dystrophies. The expected outcome is to identify the presence and extent of retinal damage or dysfunction.

Indications

• Patients with symptoms such as reduced vision, night blindness, or visual field defects.
• Unexplained vision loss.
• Screening for inherited retinal disorders.
• Monitoring disease progression and treatment efficacy.

Preparation

• No special dietary restrictions or fasting is generally required.
• Patients should avoid using eye makeup.
• Pupils may need to be dilated with eye drops.
• A comprehensive eye exam may be done beforehand.

Procedure Description

1. The patient is seated comfortably.
2. Special contact lenses or adhesive electrodes are placed on the cornea and around the eyes.
3. The test involves looking at a display screen that shows a series of flashing lights or patterns.
4. Electrical signals produced by the retina in response to these visual stimuli are recorded.
5. The data is analyzed to produce a map of retinal function.

Duration

The procedure typically takes about 45 minutes to an hour.

Setting

The procedure is performed in an ophthalmological clinic or specialized diagnostic center.

Personnel

• Ophthalmologist or a specially trained optometrist.
• Technicians who operate the ERG equipment.

Risks and Complications

• Mild discomfort from the contact lens or electrodes.
• Rarely, allergic reactions to eye drops used for pupil dilation.
• Minimal risk of corneal abrasion.

Benefits

• Non-invasive.
• Provides detailed information about retinal function.
• Helps in early diagnosis and monitoring of retinal diseases.
• Can guide treatment decisions and assess their effectiveness.

Recovery

• Minimal downtime; patients can resume most normal activities immediately.
• Temporary blurriness or light sensitivity if pupils were dilated.
• Follow-up appointments may be needed based on results.

Alternatives

• Optical Coherence Tomography (OCT) - provides structural imaging of the retina.
• Visual Field Testing - assesses the entire scope of vision.
• Advantages of mfERG include functional assessment of the retina, which other tests may not provide.

Patient Experience

• The patient may feel slight discomfort from the electrodes.
• Light flashes can be intense but are usually not painful.
• After the procedure, there might be some temporary visual disturbances or light sensitivity, especially if dilation was performed.
• Pain management is generally not required, and comfort measures include ensuring a relaxed setting and providing reassurance throughout the procedure.