If you are unable to see in detail or your vision does not have sharpness, it is referred to as blurred vision. Blurred vision can be caused in either one or both the eyes; however, it is dependent on the cause. It can be caused due to birth defects or abnormalities like near sightedness or far sightedness. It can be indicative of serious eye disease or can be corrected by eyeglasses.

For example, a 31-year-old man who had good vision complained of bouts of sudden blurred vision. It cleared up quickly, but it is still worrisome whenever it happens. Let us look at what causes sudden blurred vision?

What Causes Sudden Blurred Vision?

It is very important to rule out any causes, which are responsible for sudden blurred vision, as it is a very delicate system. It can be normal, due to a minor condition or sometimes due to very concerning causes. A doctor should be consulted or an appointment with the ophthalmologist should be fixed.

• Sudden blurred vision can be normal in some situations. If there is movement between a close and faraway object, it can cause blurriness, as the eyes take time to adjust to the new depth. It can also be caused when there is presence of tears or fluid in the eyes.
• Minor conditions, which cause blurred vision, are astigmatism, worsened vision, and viral or allergic conjunctivitis.
• Worrisome causes of blurred vision can be when there is no adequate blood supply to the eyes. Problems of the heart valve and heart rhythm, or overheating and dehydration can all lead to sudden blurred vision. 

Even when the blurred vision clears up, it can be caused due to glaucoma, uveitis (eye inflammation of middle layer of eye tissue) or even torn retina. If vision is lost in an eye, it can be a very early symptom of stroke. Very high blood pressure, internal bleeding in the head or development in brain mass can cause increased pressure in the head, which can also lead to sudden blurred vision.

It helps to compare symptoms of common causes so that you know what’s behind the blurriness. Let us look at various causes of sudden blurred vision and their treatments:

1. Myopia (Nearsightedness)

Myopia is also known as nearsightedness, which can cause blurred vision in one or both eyes. It can also cause strain on the eyes, squinting and headaches. Due to refractive error, objects in the distance appear blurred.

It can be treated by using corrective lenses, eyeglasses or surgery like LASIK or PRA.

2. Hyperopia (Farsightedness)

It is also known as farsightedness, where objects, which are close, cannot be focused on properly. Far away objects appear sharp, but it puts strain on the eyes and causes fatigue. Sometimes distant objects also appear blurred, however, it can be corrected by using glasses, lenses or with surgery.

3. Astigmatism

When there is blurred vision at all distances, it can be because of astigmatism, which is caused when there is irregular shaped cornea. The light rays do not fall in a single clear point on the retina, thus making a blurred image. Glasses, lenses and surgery can correct this.

4. Floaters

Having floaters is a normal sign of ageing, where bits of tissue float in the vitreous fluid and cast a shadow on the retina. This can cause sudden blurred vision due to the spots. However, if there are lots of floaters appearing suddenly, doctor should be consulted.

5. Drops & Medication

Some types of medicated eye drops cause blurry vision due to the preservatives present in them. Using artificial tears can be helpful in such cases. Allergy medication can also cause blurred vision and dry eyes.

6. Overuse of Contact Lenses

When contact lenses are worn for periods longer than they have been prescribed for, it causes buildup of debris and proteins. This debris can cause infection and also blurred vision.

7. Presbyopia

This is a type of nearsightedness, which is caused after the age of 40 – 45 years. The lens in the eyes gets hardened and thus there is inability to focus on the nearby objects. Bifocal or progressive lenses are required to correct this. Surgery can also be done.

8. Chronic Dry Eyes

When the eyes are not properly lubricated with tears, it leads to dry eye syndrome. It can cause fluctuating and blurred vision. Artificial tears can help and for more advanced cases punctal plugs are used.

9. Pregnancy and Hormones

Hormonal changes during pregnancy cause blurred and double vision by altering the shape and thickness of the cornea. Besides, pregnant women also have dry eyes. Although not serious in most cases, sudden blurred vision could also be a symptom of gestational diabetes or high blood pressure.

10. Migraine Headaches

Migraine headaches start with symptoms like blurry vision, halos, flickering lights or zigzag patterns. They are usually harmless and temporary.

11. Blurred Vision Post LASIK

When refractive surgery like LASIK is done, it can cause blurred vision for sometime. It can take from a few days to weeks for the vision to normalize.

Take a test here to see the causes for sudden blurred vision or other vision problems.