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Retinal Disease Testing: When to Get Tested & More

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Retinal disease testing is one of the first steps in determining if you have a retinal condition, identifying the specific issue, and prescribing the most appropriate treatment. There are many different types of tests, most of which are noninvasive.

If you think you may have a retinal disease or any other eye health condition, talk to your doctor about your symptoms and how to get tested.

Testing for Retinal Diseases

There are a variety of retinal diseases and disorders a person can develop, including the following:

  • Macular degeneration
  • Diabetic eye disease
  • Retinoblastoma (cancer of the retina)
  • Macular holes or puckers

There is also a group of inherited retinal diseases (IRDs) caused by one or more genes not working as they should. These conditions include the following:

  • Retinitis pigmentosa
  • Choroideremia
  • Stargardt disease
  • Cone-rod dystrophy
  • Leber congenital amaurosis

If you’re concerned you may have or be at risk for developing a retinal disease, talk to a medical professional. They can give you a comprehensive exam, perform any additional tests they feel are appropriate, and form a treatment plan with you if any issues are discovered.

If you’re already experiencing visual symptoms, such as any blurriness, vision loss, floaters, or anything else unusual, see a doctor as soon as possible even if you don’t think you have a retinal condition. The eye is a sensitive organ and issues can often worsen over time, potentially causing permanent damage, if left untreated.

Tests for Retinal Diseases

Full-Field Electroretinogram (ffERG)

An electroretinogram (ERG) involves monitoring electrical activity in the retina in response to a stimulus. As cells react to stimuli, they send electrical signals specialized machines can interpret, and a doctor can then use them to watch for abnormalities.

A full-field electroretinogram (ffERG) tests for mass response, with contributions from multiple retinal sources. In essence, it tests for conditions that cause widespread retinal dysfunction, including cancer retinopathy and rod/cone dystrophies.

During the test, electrodes are placed on the surface of your eyes. While this may cause some discomfort, it is much less invasive than many patients imagine and very safe.

These devices measure signals your retinal neurons send. They do not shock your eyes. A doctor will use a flashing light to stimulate your eyes.

Multifocal Electroretinogram (mfERG)

A multifocal electroretinogram (mfERG) is similar to the above, with the tests often performed on the same patient.

An mfERG is more localized than an ffERG. This helps a doctor get important spatial information, which is not possible to obtain from an ffERG alone.

While the information a doctor obtains from this test is different, the test is going to feel more or less identical to the average patient compared to a ffERG.

Visual Evoked Potential (VEP) or Visual Evoked Response (VER)

Visual evoked potentials (VEP) testing, sometimes called visual evoked response (VER) testing, is a test that measures the signals sent along your visual pathways. Electrodes are placed on the head, allowing a machine to see how your eyes “speak” to your brain when you are shown different visual stimuli.

This type of testing typically has two parts. First, you will be shown a pattern on a screen of black and white squares, which will move and change in size. Then, a machine is used to flash light in your eyes. This process takes about an hour, with the pattern testing taking longer than the flashing lights.

It is noninvasive and very safe. The only real discomfort is generally caused by the flashing lights.

Electrooculogram (EOG)

An electrooculogram (EOG) is a test that uses a small electrical charge to test the electrical potential in key areas of your eye. Both normal and abnormal readings, combined with other data points, can help a doctor eliminate potential conditions a patient may or may not have.

The test is noninvasive, and the electrical charge administered during an EOG is difficult to impossible to detect. The most discomfort a patient might feel comes from the dilation drops used, which may make you sensitive to light and unable to perform certain tasks for 6 to 12 hours.

Dark Adaptometry Testing

Dark adaptometry or dark adaptation testing is a test sometimes used to detect the early signs of age-related macular degeneration. It involves a doctor seeing how long it takes your eyes to adapt from bright light to darkness.

While old methods took a moderate amount of time (20+ minutes), more modern testing only takes a few minutes. You will look into a machine and hit a button whenever you notice a subtle blinking light.

This test is painless. A patient only needs to look into a machine and click a button if they see a signal.

Visual Field Tests

There is a collection of tests doctors can use to test your visual field, which can identify if a patient is potentially affected by certain eye conditions, such as glaucoma. Two of the most common include a confrontation visual field test and an automated static perimetry test.

A confrontation visual field test involves looking at an object with an eye closed. While looking at the object, a doctor will hold out a certain number of fingers in the periphery of your vision and ask you to call out the number without moving your eyes.

While this is a basic test, it can still provide important information that a doctor can investigate further.

An automated static perimetry test is in many ways a more advanced version of a confrontation visual field test. You will stare into a machine through a window that is somewhat bowl-shaped and asked to look at a dot. While looking at that dot, you will then press a button whenever you see another dot appear somewhere on the bowl.

During both of these tests, you can blink and will generally experience no discomfort beyond needing to focus more than usual on a single point.

Remember that these tests are somewhat easy to “cheat” in that you can try looking around for the signals, but that defeats their purpose. You want accurate results more than “good” results for a proper diagnosis.

Color Vision Test

A color vision test is designed to check if the eye’s cone cells can interpret colors correctly. While you should get these tests performed by a professional if you expect a problem, many people have seen these tests online already.

A patient will look at an image that is generally a series of colored dots arranged in a circle. Some of the dots will be colored differently, forming a squiggle or a number, and the patient will be asked to describe them.

For people with normal color vision, these tests are very easy. However, patients with some level of color blindness may have a harder time or be totally unable to distinguish the pattern within certain combinations of colors.

In either case, the test is completely noninvasive. You will just be asked to look at some images and describe them.

Genetic Testing for Retinal Diseases

Inherited retinal diseases are genetic in nature, meaning it is sometimes helpful for a patient to receive genetic testing.

Genetic testing, which is generally recommended for young patients who are at risk of having an IRD, involves taking a genetic sample from a patient (usually blood or spit) and then sending it to a lab to check the patient’s genetic status. A medical professional can use this information to confirm whether a patient has a condition or to determine whether further testing is necessary, potentially catching a disease before a patient shows any significant symptoms.

The necessity of genetic testing is somewhat debated in many cases. Insurance companies often won’t cover it. In the past, not much could be done with the early diagnosis due to the nature of IRDs.

However, as medical science advances and certain gene therapies are developed, it is becoming more worthwhile to get tested early if it’s suspected that a patient may be at risk for an inherited retinal disease or other genetic condition. If you have a child at risk for an IRD, it is worth discussing genetic testing and potential gene therapies with a doctor.

You may also want to consider medical trials in some cases. Understand that all medical testing carries inherent unknowns, which should always be weighed against the potential benefits (and the likelihood of those benefits occurring) of the trial.

Who Performs Retinal Testing?

Both optometrists and ophthalmologists can generally perform retinal testing, although some types of tests involve the use of machines that not all facilities necessarily have access to. Reputable medical professionals will make you aware of this fact and help you get access to testing they can’t perform themselves due to either regulations or a lack of equipment.

Most people can start checking if they have a retinal or other eye health condition with their primary care provider who can then refer them elsewhere as necessary.

What Comes After Retinal Testing?

The next steps after retinal testing depend on the results. Assuming a condition was detected, a doctor can help you form a treatment plan.

It is important to have realistic expectations at this stage. Not all eye health conditions can be cured, but almost all can be treated to help you control your symptoms, slow any potential progression, and improve your overall quality of life.

References

  1. Diagnostic Sensitivity and Specificity of Dark Adaptometry for Detection of Age-Related Macular Degeneration. (March 2014). Investigative Ophthalmology & Visual Science.
  2. Electrooculogram. (March 2021). American Academy of Ophthalmology.
  3. Electroretinogram. (February 2021). American Academy of Ophthalmology.
  4. How Color Blindness Is Tested. (August 2017). American Academy of Ophthalmology.
  5. Retinal Disorders. (August 2016). MedlinePlus.
  6. The Ins and Outs of Genetic Testing for Inherited Retinal Diseases. (August 2021). Retina Today.
  7. Visual Evoked Potentials (VEP) Testing. UPMC.
  8. Visual Field Test. (March 2022). American Academy of Ophthalmology.
  9. What are Inherited Retinal Diseases (IRDs)? Prevent Blindness.
  10. Full-Field Electroretinogram. (April 2022). StatPearls.
  11. Full-Field versus Multifocal Electroretinography. (July 2013). Journal of Ophthalmologic & Vision Research.
  12. Diagnostic Yield of Panel-Based Genetic Testing in Syndromic Inherited Retinal Disease. (December 2019). European Journal of Human Genetics.
  13. Diagnostic Accuracy of Confrontation Visual Field Tests. (March 2011). Neurology.

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