Metamorphopsia is a visual defect that causes linear objects, such as lines on a grid, to look curvy or rounded. It’s caused by problems with your eye’s retina, and, in particular, the macula.
The retina is a thin layer of cells at the back of your eye that senses light and sends — via the optic nerve —impulses to the brain, allowing you to see. The macula sits in the center of your retina and helps you see in clear detail.
Metamorphopsia can result when either of these parts of your eye is affected by disease, injury, or age.
Metamorphopsia affects central vision (versus peripheral, or side vision) and distorts the appearance of linear objects. It can occur in one eye or both. When you have metamorphopsia, you may find that:
- Straight objects, like a signpost, appear wavy.
- Flat things, such as the sign itself, look rounded.
- Shapes, such as a face, can appear distorted. In fact, some have likened metamorphopsia to looking at a Picasso painting, with its multidimensions.
- Objects appear smaller than they are (called micropsia) or larger than they are (macropsia). According to 2016 research, micropsia is more common than macropsia.
Metamorphopsia can be a symptom of a variety of eye disorders that affect the retina and macula. These include:
Age-related macular degeneration (AMD)
- the leading cause of vision loss among those 50 years and older
- not apt to occur until after age 60
- linked to genetics
- possibly related to environmental factors like diet and smoking
- 45 percent of study subjects had visual distortions of lines (for example, newsprint or computer displays)
- 22.6 percent noticed distortions of window frames and bookshelves
- 21.6 percent had distortions of lines of bathroom tile
- 18.6 percent experienced distortions of faces
There are two types of AMD:
- Wet. Blood vessels leak fluid or blood into the macula (less common than dry AMD).
- Dry. There’s no leakage of fluid or blood into the macula. The macula gets thinner due to aging, where yellow-colored lipid fatty proteins (called drusen) clump under the surface, causing vision loss.
Wet AMD is more likely to produce metamorphopsia than dry AMD.
Epiretinal membranes (ERMs)
ERMs are also called macular puckers. They’re caused by a defect in the surface lining of the retina. This defect can be caused by age, retinal tears, and diseases like diabetes, which affect vascular regions in the eye.
ERMs begin with cells growing on the smooth retinal membrane. This cellular growth can contract. This pulls on the retina and causes distorted vision.
About 20 percent of people in the United States over the age of 75 have ERMs, although not all cases are severe enough to require treatment.
This is a condition in which fluid builds up in the macula. This fluid can leak from surrounding blood vessels that become damaged due to:
- diseases like diabetes
- eye surgery
- certain inflammatory disorders (such as uveitis, or inflammation of the eye’s uvea or middle layer of the eye)
This extra fluid causes the macula to swell and thicken, causing distorted vision.
When the retina detaches from the structures that support it, vision is affected. This may occur due to injury, medical condition, or trauma.
Retinal detachment usually starts in the periphery of the retina. But, central vision can be impacted if the macula is affected.
Call your ophthalmologist if available, call 911, or go to the nearest emergency room.
As the name implies, a macular hole is a small tear or break in the macula. This break can happen due to age. It occurs when the gel that gives the eye its round shape shrinks and contracts, pulling away from the retina and causing tears.
Doctors use several techniques — most involving charts or graphs with lines — to help diagnose metamorphopsia.
People who see distortions in the lines when there aren’t any are more likely to have a retina or macular problem and subsequent metamorphopsia.
Your doctor may ask you to look at a chart called the Amsler grid, named after the creator Dr. Marc Amsler. Much like the grid paper used in geometry class, it has evenly spaced horizontal and vertical lines with a central focal point.
During an exam, you’ll focus on the central point in the grid without letting your eye wander. Your eye doctor will ask you questions like “Are all the squares the exact same size?” to see whether you have any distortion in your vision and where the distortion is.
The grid can test your vision in the central 10 degrees of your vision. It was the first test developed to evaluate metamorphopsia.
Preferential hyperacuity perimeter (PHP)
PHP is a computerized test in which dotted lines are flashed before you on a screen. In each line, a small number of the dots are misaligned to make a bump or wave. The test administrator will ask you to point out these artificial distortions.
The amount of distortion in your vision can be quantified by measuring how well you detect varying degrees of distortion in the lines.
M-charts were developed to better quantify the degree of metamorphopsia in horizontal and vertical directions compared to an Amsler grid. These charts are made up of either one or two straight lines created from small dots, again with a central focal point.
People with metamorphopsia will interpret these straight lines as irregular or curved. The lines are shown vertically and horizontally to measure distortion in both directions.
(PHP and M-charts are rarely used.)
Since metamorphopsia is a symptom of a retina or macular problem, treating the underlying disorder should improve the distorted vision.
For example, if you have wet AMD, a doctor may recommend laser surgery to stop or slow blood leaking from faulty vessels in your retina.
If you have dry AMD, you may be advised to take certain supplements, such as vitamins C and E, lutein, and zeaxanthin, which have been shown to slow the disease.
If you have a detached retina, surgery to reattach it will be necessary. Any related metamorphopsia should improve — but it may take time.
In one 2016 study, more than half of study subjects still had some metamorphopsia a year after successful surgery for a detached retina.
The distorted vision that’s a hallmark of metamorphopsia is a common symptom of retina and macular eye problems.
Depending on the underlying condition and its severity, the metamorphopsia may be significant or not. In general, however, once the eye disorder causing the vision problem is treated, the metamorphopsia improves.
Speak with a doctor if you notice any changes in your vision. As with any condition, earlier detection and treatment result in a better outcome.
A retinal specialist can provide treatments to help slow the progression of wet AMD, protect your vision, and (in some cases) help improve your vision loss. Getting injections of anti-VEGF drugs can help slow leakage from blood vessels and restrict the growth of new abnormal blood vessels, helping preserve your vision. Some types of wet AMD can also be treated with laser surgery.
While wet AMD doesn’t usually cause blindness, it can lead to deterioration of your central vision. A low vision specialist can help you maximize your remaining vision. These specialists are usually optometrists or ophthalmologists trained to help you adapt to low vision through lifestyle adjustments, changes to your home and workplace, and the use of vision aids.
Living with low vision may put you at higher risk of anxiety and depression. It can also lead to loneliness if it keeps you from socializing. A psychologist, licensed professional counselor, or clinical social worker can diagnose mental health conditions and use psychotherapy to help you cope. A psychiatrist can prescribe medication, if necessary.
Smoking can make some treatments aimed at slowing the damage from wet AMD less effective. If you smoke, a smoking cessation counselor can help you develop strategies to quit and manage withdrawal symptoms. This may include prescribing medication.
People with wet AMD may be more likely to develop cardiovascular disease, especially as the condition progresses. A cardiologist can screen you for signs of heart disease and prescribe medications, if necessary. They can also offer recommendations for lifestyle changes, such as starting an exercise routine, that can reduce your risk of heart disease.
Following a nutritious diet can be an important part of managing wet AMD. Certain foods — such as leafy greens, seafood, and yellow fruits and veggies — have been shown to help the condition. A dietitian can provide a personalized eating plan to make sure you’re getting the recommended nutrients. They can also suggest foods rich in lutein and zeaxanthin, which can reduce the risk of advanced AMD.