Sudden Blurred Vision: Understanding the Causes & What to Do

Sudden blurred vision can be an unsettling experience. When your eyesight changes without warning, it may indicate something temporary or signal a more serious underlying issue.

Understanding why this happens can help you recognise when to seek medical attention and how to protect your vision.

What Is Sudden Blurred Vision?

Sudden blurred vision, sometimes called sudden blurry vision, is a rapid loss of visual clarity. It can affect one or both eyes and may appear as hazy or cloudy vision or difficulty focusing on details.

Why Clarity Matters

Your eyes work together with your brain, blood vessels, and optic nerve to provide clear sight. When any of these components are disrupted, it can cause blurred vision or sudden visual disturbances.

Common Causes of Sudden Blurred Vision

Several factors may cause blurry vision to occur unexpectedly. Some are temporary, while others require immediate medical help.

Refractive Errors

Refractive errors such as short-sightedness, long-sightedness, or astigmatism can cause blurred vision when the eye’s shape prevents light from focusing on the retina.

Dry Eyes

When your eyes do not produce enough tears or the tears evaporate too quickly, you might experience hazy vision. Artificial tears or prescribed eye drops can help restore comfort and clarity.

Contact Lens Issues

Wearing lenses for too long or not cleaning them well can lead to blurry eyesight, eye infections, and irritation. Always follow your optometrist’s advice for lens care and replacement.

Eye Infections and Inflammation

Eye infections, such as conjunctivitis or keratitis, may cause blurred vision and redness. Inflammation of the optic nerve, also called optic neuritis, can also lead to sudden vision loss or pain when moving the eyes.

High Blood Pressure

High blood pressure might damage the blood vessels in the retina, affecting blood flow and leading to sudden blurred vision. Regular eye checks can help identify early signs of this condition.

Low Blood Sugar

Low blood sugar can cause blurry vision, particularly for people with diabetes. Adjusting your glucose levels may help restore normal vision, but persistent changes should be discussed with your doctor.

Migraine With Aura

Some people experience visual disturbances like flashing lights, zigzag patterns, or cloudy vision before migraines. These episodes usually resolve, but frequent occurrences warrant a professional review.

Macular Degeneration

Age-related macular degeneration affects the central vision, making it difficult to see fine details. While the onset is usually gradual, sudden changes should not be ignored.

Stroke or Transient Ischaemic Attack

Sudden blurred vision in one eye, difficulty speaking, or loss of coordination may indicate a medical emergency. Prompt medical attention is essential to prevent further complications.

Optic Nerve Conditions

The optic nerve transmits visual signals from the eye to the brain. Conditions affecting this nerve, such as inflammation or poor blood flow, can cause blurred or double vision.

When to Seek Medical Help

If your vision suddenly becomes blurry, especially if it’s accompanied by other symptoms such as flashing lights, headaches, or difficulty speaking, it’s important to seek medical help promptly. Early assessment allows for accurate diagnosis and appropriate management.

Temporary Versus Persistent Blurring

Not all sudden vision changes indicate serious conditions. Fatigue, eye strain, or exposure to bright light may cause temporary haziness that improves with rest or artificial tears. However, an eye care professional should always evaluate persistent blurry eyesight.

Diagnosing the Cause

An eye doctor can perform several tests to identify what may cause blurred vision. These may include examining your retina, checking eye pressure, or evaluating the optic nerve. The goal is an accurate diagnosis to determine the best course of action.

Managing Blurred Vision

Treatment depends on the underlying cause. Common management approaches include:

• Eye drops for dryness, infections, or inflammation
• Corrective lenses to address refractive errors
• Protective eyewear to prevent injury or further irritation

Preventing Sudden Changes In Visual Field

You can take practical steps to protect your eyesight:

• Wear eye protection when exposed to dust, chemicals, or bright light.
• Stay hydrated to help the eyes produce sufficient tears.
• Keep regular eye examinations to detect issues early.

 

 

Frequently Asked Questions

Can stress cause blurry vision?

Yes. Stress can contribute to eye strain or temporary visual disturbances, but persistent symptoms should be evaluated.

Can dehydration cause blurry vision?

Yes. Dehydration can reduce tear production, leading to temporary haziness or discomfort. Drinking enough water and using artificial tears may help improve clarity.

What’s the difference between blurred vision and double vision?

Blurred vision makes things look out of focus, while double vision means seeing two images of a single object. Double vision may indicate an issue with eye muscles or the optic nerve.

Conclusion

Sudden onset of blurred vision can have many causes, from simple eye strain to conditions that require immediate attention. Understanding the possible reasons, recognising other symptoms, and seeking timely medical help are key to maintaining healthy eyesight.

If your vision suddenly becomes unclear, don’t wait for it to improve on its own. An eye examination can allow for an accurate diagnosis and the right guidance.

If your vision is blurry, it’s important to have your eyes examined by a qualified professional. Our friendly team can help identify what may be causing your visual changes and guide you towards appropriate care options.

Book an eye consultation with Dr Anton Van Heerden at 03 9000 0389 and proactively protect your sight and overall eye health.

Note: Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.

References

Gardner, A. (2025, April 20). 8 Causes of Blurry Vision—and When To Seek Care. Health. Retrieved October 28, 2025, from https://www.health.com/condition/eye-health/blurry-vision-causes

Lipner, M. (2025, August 18). What Causes Sudden Blurry Vision? Verywell Health. Retrieved October 28, 2025, from https://www.verywellhealth.com/sudden-blurry-vision-5092267