What Causes Sudden Blurred Vision?

by Health News

People depend on clear, sharp vision in all areas of life, from scanning road signs or working at a computer to enjoying a good book.  When vision blurs, objects become hazy and out of focus.  Sudden blurred vision can be very concerning, but learning more about causes can help dispel fears and ensure optimal eye health.

Sudden blurred vision may affect the entire line of sight or just parts of it.


Blurred vision that comes on suddenly can affect all or parts of the visual field.  People may experience clouded or dim vision in one eye or in both eyes.

Causes of Sudden Blurred Vision

The most common causes of blurred vision are refractive errors, which are visual problems that occur when the shape of the eye affects the ability to focus.  Refractive errors include myopia, hyperopia, astigmatism, and presbyopia.

Myopia – Also known as nearsightedness, myopia causes objects in the distance to become blurred and can affect one or both eyes.  Treatment for myopia includes eyeglasses, contact lenses, and refractive eye surgery.

Hyperopia – People with hyperopia (or farsightedness) experience blurry vision when viewing objects nearby and clearer vision in looking at objects farther away.  Treatment for hyperopia also includes eyeglasses, contact lenses, or refractive eye surgery.

Astigmatism – Caused by an irregularly-shaped cornea, astigmatism produces blurred vision at all distances because light rays do not come to a single focal point on the retina. This condition is also corrected with eyeglasses, contact lenses, or refractive surgery.

Presbyopia – An eye condition that typically affects people over 40 years of age, presbyopia results from a hardening of the eye's lens.  It blurs vision when people are trying to read small print like that on product labels, books, and newspapers.  People can correct this condition with the help of reading glasses, glasses with multifocal lenses, or surgery.

While refractive errors make the most common causes for sudden blurred vision, it can be a symptom of a number of other conditions or injuries.  These include:

  • Abrasions to or scarring of the cornea
  • Age-related macular degeneration
  • Cataracts
  • Diabetic retinopathy
  • Infectious retinitis
  • Retinitis pigmentosa
  • Eye injury
  • Migraine headaches
  • Stroke

Related:  Antioxidants and Vision Health:  Three Factors that Could Affect Your Vision

When to Seek Medical Help for Sudden Blurred Vision

People who experience sudden blurred vision should always consult with an eye care or medical professional for an accurate diagnosis and seek immediate treatment if symptoms include eye pain or vision loss.  In addition to blurred vision, a stroke can cause severe headache, speaking difficulty, facial droop, visual problems, and loss of movement on one side of the body.  Sudden blurred vision accompanied by any of these symptoms also requires immediate medical attention.



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