Why Is My Vision Blurry?

Medically Reviewed By Ann Marie Griff, O.D.
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Blurred vision or blurry vision is a loss of sharp vision. You may experience sudden or gradual blurry vision in one or both eyes. You may find it difficult to do certain tasks or even manage your daily life. Depending on how sudden or gradual the blurry vision is, there can be a variety of reasons why you are experiencing it. It may be a minor issue such as not wearing the correct glasses or a medical emergency such as a stroke.

This article will focus on the causes of blurred vision and when you should seek medical care. It will also describe the symptoms and treatment options for the condition.

What causes blurry vision?

blurry focus eyes
Eloisa Ramos/Stocksy United

There are many reasons why your vision may become suddenly or gradually blurry.

Blurred vision can result from various mild to serious diseases, disorders, and conditions. While many cases of blurred vision are due to problems with the eyes, blurred vision can also be due to neurological and autoimmune disorders.

Certain vision changes can indicate a medical emergency, which can lead to loss of sight. You should not ignore temporary blurred vision.

Common causes of blurry vision

Common vision problems that are associated with blurry vision include:

Astigmatism

With astigmatism, light rays do not focus clearly at one point on the retina due to the unequal curve of the eye’s surface. According to the American Academy of Ophthalmology, astigmatism is common, but doctors do not know why eye shape can differ from person to person. Symptoms of astigmatism include squinting to see more clearly, blurry vision, eyestrain, and headaches.

You can correct mild astigmatism by wearing prescribed glasses or contact lenses.

Dry eyes

Dry eyes are a common condition in which the eyes can not lubricate themselves properly with natural tears. According to the National Eye Institute, dryness is common and affects millions of Americans each year. Those who are female and over 50 years old are most affected.

Treatments for dry eyes include over-the-counter eye drops, lifestyle changes including stopping smoking and limiting screen time, and even surgery to fix loose lower eyelids, though this is not common.

Eye irritation

Eye irritation refers to the uncomfortable feeling of dry, itchy eyes or the feeling of grit in your eyes. Prolonged screen time or common colds may be causes of this.

Farsightedness

Farsightedness, also known as hyperopia, occurs when the eyes do not refract light properly. This condition results in distant objects being more focused than near objects.

Eyeglasses are the most common way of correcting farsightedness.

Read more about hyperopia here.

Nearsightedness

With nearsightedness, also known as myopia, eyes focus better on near objects rather than distant objects. This condition occurs due to your eyes not focusing light properly on the retina.

People with myopia face a higher chance of a detached retina, a serious issue that can cause blindness. Symptoms include eyestrain, headaches, and squinting.

Read more about myopia here.

Presbyopia

Presbyopia is a common, gradual loss of your eye’s ability to focus on near objects due to aging.

Read more about presbyopia here.

Serious causes of blurry vision

Medical professionals should evaluate any vision change. Blurred vision can be a symptom of a serious disorder, and you should not ignore even temporary vision changes.

Retinal detachment

Your retinas are a light-sensitive tissue in the back of your eye. Retinal detachment happens when the tissue pulls away from the back of the eye.

Retinal detachment is a medical emergency. You should seek immediate medical care if you have any symptoms, including small dark spots that float across your eye, flashes of light in either eye, or a dark shadow in the middle of either side of your eyes.

Read more about retinal detachment here.

Stroke

According to the American Stroke Association, a stroke happens when oxygen and nutrient-carrying vessels burst or rupture in the brain. Part of the brain cannot get the oxygen and blood it needs, so brain cells begin to die. It is the fifth leading cause of death in the US.

There are many different types of strokes, and one of the symptoms includes blurry vision. A stroke can affect our visual pathways and how our brain processes information from our eyes.

It is important to recognize the symptoms of a stroke so brain damage can be minimal.

Read more about stroke-related eye issues here.

Brain tumor

A brain tumor can push enough on the optic nerve, and blindness can occur. The loss of vision caused by a brain tumor happens gradually. It begins with blurry vision, double vision, or a blind spot. However, as it grows to push on the optic nerve, it will result in great vision loss.

Read more about brain tumors here.

Head trauma

Your retina can tear away from the back of your eye if a head injury occurs. Vision can become blurred in one eye.

After a head injury, the retina may tear away from the back of your eye and lose its blood supply. If that occurs, your vision in one eye will become blurred. 

Traumatic brain injuries may affect your vision by damaging parts of the brain involved in visual processing.

Retinoblastoma

Retinoblastoma is a cancer of the eye that starts in the retina, the very back part of the eye. It is the most common type of eye cancer in children.

Without treatment, the tumors can take over the eyeball. Cells can break off from the main tumor and create more tumors elsewhere in the eyes.

These tumors might block the channels that let the fluid circulate within the eye, raising the pressure inside the eye. This pressure can cause glaucoma, which can lead to pain and loss of vision in the affected eye.

Read more about retinoblastoma here.

Autoimmune causes of blurred vision

Some autoimmune diseases result in blurred vision, including:

  • Multiple sclerosis: This disease affects the brain and spinal cord, causing weakness, coordination, balance difficulties, and other problems. It can often cause vision problems.
  • Myasthenia gravis: This is an autoimmune neuromuscular disorder that causes muscle weakness. Myasthenia gravis affects the voluntary muscles of the body, especially those that control the eyes, mouth, throat, and limbs.
  • Systemic lupus erythematosus: This is a disorder in which the body attacks its healthy cells and tissues. Slow, progressive vision loss can also result in more rapid vision loss from lupus.

Diseases and conditions of the eye that can lead to blurred vision

Several different diseases, disorders, and conditions that cause blurry vision include:

Cataracts

A cataract is a loss of transparency in the lens of your eye. Cataracts interfere with vision and usually develop as a result of typical aging. 

Conjunctivitis

This condition is an inflammation of the eye surface, and symptoms can include blurred vision.

Corneal ulcer

A corneal ulcer is an eye infection that causes an open sore on the cornea. Contact lenses, injuries, disorders, drugs, and nutritional deficiencies can cause open sores to form on the cornea.

Glaucoma

According to the National Eye Institute, glaucoma is an eye disease that can cause vision loss and permanent blindness through damaged nerves. Glaucoma mostly affects those over 60 who have a family history of glaucoma.

Macular degeneration

Macular degeneration can cause loss in the center of the field of vision. In dry macular degeneration, the center of the retina deteriorates. With wet macular degeneration, leaky blood vessels grow under the retina.

Optic neuritis

Optic neuritis is a condition that affects the eye and your vision. It occurs when your optic nerve is inflamed. The optic nerve sends messages from your eyes to your brain so that you can interpret visual images.

Retinal vessel occlusion

Retinal vein occlusion happens when a blood clot blocks the vein. Sometimes it happens because the veins of the eye are too narrow. Retinal vein occlusion can lead to sudden and permanent vision loss.

Diabetic eye disease

Diabetic eye disease affects those with diabetes. These conditions include glaucoma, diabetic retinopathy, diabetic macular edema, and cataracts.

Over time, diabetes can cause damage to your eyes that can lead to poor vision or even blindness.

Uveitis

Uveitis is inflammation of the uvea, the material that lines the inner eyes. Uveitis is inflammation inside your eye.

Inflammation usually happens when your immune system is battling an infection.

Depending on the cause, blurred vision can begin suddenly and disappear quickly, such as when your eyes are refocusing on a far object after reading or sun overexposure. Blurred vision can also occur in sudden, severe episodes, such as blurred vision from a detached retina or head trauma.

Encephalitis

Encephalitis is inflammation and swelling of the brain due to a viral infection or other causes.

This swelling or inflammation is called cerebral edema and can lead to the destruction of nerve cells, bleeding into the brain (intracerebral hemorrhage), and brain damage.

Encephalitis can be a mild disease. However, people most at risk of developing serious encephalitis include infants, young children, the elderly, and people with weakened immune systems.

When to contact a doctor

In some cases, blurred vision may occur with other symptoms that might indicate a serious or life threatening condition that doctors should immediately evaluate in an emergency setting. 

Seek immediate medical care if you, or someone you are with, have any of these life threatening symptoms:

Treatment

Treatment for blurred vision depends on its cause in the first place.

Be sure to look out for other symptoms of serious illnesses. Seek immediate medical care if your blurred vision worsens or occurs with other serious symptoms, such as slurred speech.

Summary

Blurry vision can be the result of various illnesses or disorders. It can be gradual or sudden and occur with other symptoms.

Depending on how sudden or gradual the blurry vision is, there can be a variety of reasons why you are experiencing it. It may be a minor issue such as staring at a computer screen for too long or a medical emergency such as a stroke or detached retina.

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Medical Reviewer: Ann Marie Griff, O.D.
Last Review Date: 2022 Apr 21
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.