How Macular Degeneration Is Diagnosed

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macular degeneration diagnosis
© Verywell, 2018

Ophthalmologists and optometrists diagnose macular degeneration by ruling out other causes of vision changes, such glaucoma or astigmatism. Accurate diagnosis is made through a combination of a clinical examination and specific tests, such as retinal photography, angiography and optical coherence tomography.

Eye Examination and Tests

To check for macular degeneration, an ophthalmologist or optometrist will perform a comprehensive eye exam. By dilating your eyes, your doctor will be able to see a magnified view of the macula. Studying the macula and other structures of the eye will help your doctor make a diagnosis and may include the following tests.

Dilated Eye Exam

Your doctor will dilate your pupils with eye drops in order to view the back of your retina. Dilation makes it possible for the doctor to check the retina for signs of disease and optic nerve damage. A dilated retinal exam allows the doctor to see a magnified view of the macula.

Your doctor may note a mottled appearance that is caused by pigmentary changes in the macula. Also, drusen may be observed. Drusen refers to yellow-colored deposits that form underneath the retina.

Ophthalmoscopy

An ophthalmoscope is an instrument used for examining the interior structures of the eye, especially the retina. It consists of a mirror that reflects light into the eye and a central hole through which the eye is examined. Your doctor will be able to detect any damage or changes in the retina and macula.

Fluorescein Angiography

Doctors will use a method of injecting a special dye into the bloodstream, then photograph the circulation of this dye within your eye. If fluorescent patches appear, your doctor may suspect leaking blood vessels in the retina.

Optical Coherence Tomography

Also referred to as OCT, this test is a way for optometrists and ophthalmologists to image the back of your eye, including the macula, optic nerve, retina, and choroid. OCT can identify regions of the retina that are thinning, indicating the presence of geographic atrophy. An OCT test is able to show changes in the retina in much greater detail than any other instrument.

Tonometry

Tonometry is a test to measure the pressure inside your eyes, referred to as intraocular eye pressure (IOP). High eye pressure can damage the delicate nerve fibers in the back of your eye, sometimes resulting in blindness.

Although elevated eye pressure is not directly related to macular degeneration, it is performed to rule out other diseases, including glaucoma. This is important so that it can be determined for sure if vision loss is coming from disease of the macular or other parts of the eye.

Fundus Autofluorescence Imaging

This imaging method uses the body’s natural fluorescence to study the retina. Certain structures in the body will light up when exposed to light. Atrophied sections of the eye do not light up, which may indicate a diagnosis of macular degeneration.

Amsler Grid

Your ophthalmologist may ask you to look at an Amsler grid. This grid will help you notice any blurry or blank spots in your field of vision.

Self Checks/At-Home Testing

Sudden changes in your vision should be reported to your doctor, as sometimes changes can mark the beginning of macular degeneration. Some people suddenly notice discrepancies when looking at things like miniblinds or other items with straight lines. Some of the lines may apper to be wavy or inconsistent with the other lines. You can quickly test your vision at home with the Amsler grid.

How to Use the Amsler Grid

The Amsler grid should be kept in a place where you will look at it every day, such as on the refrigerator door or attached to the bathroom mirror. Take a look at the grid standing about 12 to 15 inches away. Make sure you are wearing your reading glasses if you wear them regularly.

Covering one eye, look directly at the dot in the center of the grid with your uncovered eye. Note if any of the lines appear bent or wavy. Also look to see if any part of the grid looks blurry, dim, or out of proportion. Now cover your other eye and test your vision the same way.

Call your ophthalmologist or optometrist right away if you notice any changes on the grid. AMD causes vision changes over time. Treating these changes early can help to slow or prevent further vision loss. American Academy of Ophthalmology (AAO) has provided a helpful Amsler grid for your convenience.

Schedule Eye Exams

The American Academy of Ophthalmology recommends that everyone between the ages of 40 and 54 have a comprehensive eye exam at least every two to four years to help detect AMD early. By age 55, adults should schedule an eye exam every one to three years.

View Article Sources
  • Boyd, Kierstan. "Macular Degeneration Diagnosis: How is AMD diagnosed?" American Academy of Ophthalmology, 1 Mar 2017.