Seeing horizontal lines in vision?
Metamorphopsia is a visual defect that affects the retina, or more specifically the macula. This defect causes straight or linear objects, such as a grid, to appear wavy, rounded or just distorted in general.
The retina is located at the back of the eye and detects the light that enters the eye. A direct link to the images we see, the retina, sends impulses via the optic nerve to the brain. The macula is in the center of the retina and helps you see the images in clear detail.
Metamorphopsia can occur when either the retina or the macula are affected by illness, disease, or age.
Metamorphopsia affects your central vision (images we see directly in front of us) and makes linear objects appear wavy. This may occur in one or both eyes. Some things you may experience with metamorphopsia are:
- Linear objects, such as a telephone pole, appear curved.
- Flat objects, such as a street sign, appear rounded.
- Objects appear smaller than they are (this is called micropsia) or larger than they are (called macropsia). Micropsia being the more common of the two.
What Can Cause Metamorphopsia?
Metamorphopsia may be caused by a variety of different eye disorders affecting the retina and/or the macula. These disorders include:
Age-related macular degeneration (AMD)
AMD is a common degenerative disorder that affects the macula, the part of your eye that helps you see images with sharp focus and detail.
There are two types of AMD:
Dry: Dry macular degeneration occurs more commonly of the two conditions, with somewhere between 80 and 95% of macular degeneration being the dry kind. With dry macular degeneration, the thinning of the macula occurs as described in the previous section. If left untreated, this can gradually lead to vision loss.
Wet: Wet macular degeneration triggers effects on a much more rapid timescale, and is therefore more likely to lead to blindness. In wet macular degeneration, blood vessels start to grow under the retina and leak out. This causes bulging of the macula, which in turn can lead to permanent vision loss. Wet AMD is more likely to cause metamorphopsia.
Epiretinal membranes (ERMs)
ERMs are a build up of cells on the retina, causing the retina to be pulled and distorting vision. ERMs can be caused by age, retinal tears, and diseases like diabetes.
Macular edema is a condition where fluid builds up around the macula. This can be from eye surgery, disease, or inflammatory disorders. The fluid around the macula creates swelling and distorts the vision.
Retinal detachment is exactly what you’d think, the retina detaches from the structures that support it. Usually starting in the peripheral but in some cases can affect central vision if the macula is also affected.
Be cautious, retinal detachment is an emergency. If you experience any symptoms such as floaters, or flashes of light seek medical attention urgently.
Again just as it sounds, a macular hole is a tear or hole in the macula. Usually as a result of age, it is caused by the shrinking of the gel that makes the eye round, and pulls causing tears.
Many different techniques are used to diagnose Metamorphopsia, all usually include using lines or graphs. When a patient sees distortions in the lines or grids where there isn’t any, it is usually an indication of a retina or macular problem causing the metamorphopsia. Some of the tests used to diagnose metamorphopsia include:
- Amsler Grid
- You’ll be asked to stare at a grid with evenly spaced lines, not letting your eye wander, and asked if all the squares are the same size.
Preferential hyperacuity perimeter (PHP)
- This computerized test will show you dotted lines with purposefully placed distortions. You’ll be asked to identify where the distortion is.
- Designed to identify the degree of metamorphopsia in horizontal and vertical directions. You’ll be asked to stare at a focal point of dotted lines and identify where you see the distortion of the line.
As explained above metamorphopsia is a symptom of retina or macular problems. Treatment would include diagnosing the root of the problem and treating accordingly.
For example if the cause of your metamorphopsia is dry AMD, your doctor may suggest taking certain vitamins and supplements that have been shown to slow the disease.
Depending on the underlying condition and cause of the metamorphopsia the severity of symptoms will vary. With treatment of the cause, metamorphopsia will greatly improve.