Causes of Blurred, Dark, or Partial Vision


Vision loss can affect one or both eyes. Depending on the cause, a person may experience vision loss with dim, partial, or blurry vision.

Some forms of vision loss are temporary, while others are irreversible. Either way, people can often take steps to improve or correct their vision.

Vision loss can happen suddenly or gradually over time. The best treatment will depend on the cause.

According to Centers for Disease Control and Prevention (CDC)vision problems are among the top 10 disabilities in adults and one of the most common disabilities in children.

This article examines the symptoms and possible causes of vision loss in one eye. It also discusses potential treatments.

“Vision loss” is a term for the loss of the ability to see properly without requiring some form of intervention, such as glasses.

There are different types of vision loss with various causes:

  • central vision loss, which affects the center of a person’s vision
  • loss of peripheral vision, which affects the edges of vision
  • total vision loss
  • night blindness or difficulty seeing in low light conditions
  • hazy, hazy, or hazy vision
  • difficulty seeing shapes or seeing only shadows

Other symptoms may also occur depending on the cause of vision loss.

Sudden vision loss occurs quickly, over a period of seconds or minutes to days. In the following sections, we discuss possible causes of sudden vision loss.


Migraine can often cause visual symptoms known as migraine aura. Typical migraine visual effects involve an area that a person cannot see clearly.

It is estimated that 25-30% of migraine sufferers experience symptoms of visual aura. Auras can occur with or without a headache.

Common visual disturbances include:

  • see zigzag lines
  • tunnel vision
  • loss of vision on the left or right side
  • complete loss of vision

Migraine auras usually last 10 to 30 minutes or less than an hour. Some only last a few seconds. Avoiding bright lights and loud sounds and taking migraine medication can ease symptoms.

Read about natural treatments for migraine here.

Detached retina

A detached retina occurs when the retina lifts from the back of the eye. It can cause complete or partial loss of vision in the affected eye. When a person has a detached retina, it may seem like something is blocking part of their vision.

A detached retina is serious. If left untreated, it can lead to permanent vision loss. Treatment involves some form of surgery depending on what the person’s doctor recommends.

Black eye

A black eye occurs as a result of an injury to the eye and can affect a person’s vision.

“A black eye” is a term that refers to bruising around the eye, usually caused by impact to that area. Increased pressure inside the eyeball can result from any swelling caused by a black eye. This in turn can lead to vision loss.

Learn how to get rid of a black eye here.

Corneal abrasion

Sudden vision loss can also result from an injury to the eye. A corneal abrasion is a small scratch on the cornea, which is the clear window at the front of the eye.

Depending on the severity of the injury, corneal abrasions may be temporary or permanent, and treatment may vary accordingly.

Most corneal abrasions heal on their own within 24 to 72 hours and without further complications. However, a person should see a doctor immediately if there is anything stuck in the eye.

In some cases, vision loss occurs gradually and may be harder to notice. For some people, this is related to aging. In other cases, it may be from a medical condition.


Amblyopia, also known as lazy eye, is a type of poor vision that affects only one eye.

According to National Eye Institute (NEI)amblyopia is the most common cause of vision loss in children, affecting up to 3% of them.

A breakdown in the way the brain and eye work together means that the brain does not translate images from one eye and the child relies more on the other eye.

This causes vision in the affected eye to worsen over time. Treatment can involve corrective devices, such as glasses, and in some cases even surgery.

Wearing an eye patch over the stronger eye can help retrain the weaker eye.


A cataract is a cloudy area in the lens of the eye. Cataracts can be unilateral, affecting one eye, or bilateral, where they form in both eyes.

A cataract can make a person’s vision blurry, blurry, or less colorful. It often develops gradually, so many people are unaware that it is developing.

Cataracts are very common. According to NISmore than half of all Americans age 80 or older have cataracts or have had surgery to remove cataracts.

Eye surgery is the main treatment for this eye condition.


Glaucoma is the name given to a group of diseases that can damage the optic nerve, located at the back of the eye. Glaucoma can drive to vision loss and blindness.

Symptoms can be so gradual that a person may not know they have glaucoma until they have an eye exam. They may lose vision slowly, starting with peripheral vision. Glaucoma can occur in one eye or both eyes.

In angle-closure glaucoma, pressure within the eye can increase rapidly and cause pain, nausea, vomiting, or loss of vision. Medical professionals usually treat it with eye drops. Sometimes, however, laser or surgical intervention may be necessary.

Without treatment, glaucoma can eventually lead to blindness. Prescription eye drops are the primary treatment for glaucoma. By lowering the pressure in the eye, eye drops can prevent further damage to the optic nerve. However, they cannot reverse damage already done.

A person should seek immediate medical attention if any of the following occur simultaneously with symptoms of vision loss:

  • severe headaches
  • difficulty speaking
  • drooping face
  • loss of muscle control on one side of the body
  • severe eye pain

These could be signs of a stroke or other serious medical condition.

As a rule, vision loss is not a consequence of the natural aging of the eye. Vision loss is usually the result of an eye condition, eye injury, or both.

Vision loss is not always permanent. In many cases, people can treat or correct their vision loss.

The American Foundation for the Blind provides resources to help people manage new vision loss.


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