What causes blurred vision?
Here are some common causes:
Concentrating your eyes on the same spot for too long, especially something electronically lit like a mobile phone or computer, can lead to your eyes becoming over-tired – causing blurred vision and headaches.
An eye infection such as conjunctivitis can cause blurred vision. This is caused by inflammation within the eye. Bacterial eye infections can also cause blurred vision, usually from pockets of pus around the lash line which leak pus onto the surface of the eye. 1
Blurred vision and headache could be a symptom of a migraine. Migraines are severe, pounding headaches and can be accompanied by ‘aura’ – which refers to vision disturbances including flashes of light, dark spots and wiggly lines.
This is when the retina – a thin layer of tissue at the back of the eye – becomes loose. This causes dots and lines in the vision, as well as flashes of light or shadows.2
This needs immediate medical treatment as it can cause vision loss.
Often, blurred vision is caused by short or near sightedness, or astigmatism, which isn’t being properly corrected. Even if you don’t think you need glasses, you should get your eyes checked regularly as vision changes over a lifetime. If you do wear glasses or contact lenses, make sure your prescription is up to date.
Concussion can cause you to experience sudden blurred vision. You should always speak to your doctor if you have hit your head and feel drowsy, confused or have vision changes.
Hyphema occurs when your eye has experienced trauma such as a sudden blow. Blood pools inside the iris and pupil area, causing pressure changes and light blocking, which leads to blurriness. You should always see a professional for treatment if you think you might have hyphema. 3
What is blurred vision in pregnancy a sign of?
- Blurred vision in pregnancy is usually a sign of hormonal changes altering the thickness of your cornea. 4
- It could also be a sign of gestational high blood pressure, which develops after 20 weeks of pregnancy and goes away within 6 weeks of the baby's birth. Your midwife should be monitoring your blood pressure during antenatal appointments. 5
- Blurred vision in pregnancy is also a sign of pre-eclampsia. This is a serious condition which can affect women after 20 weeks of pregnancy. Other symptoms include pain below the ribs, swelling, sickness and headaches – seek urgent medical attention. 6
What causes blurred vision in one eye?
- Blurred vision, blind spots which only affect one eye and pain could be a sign of optic neuritis (inflammation of the optic nerve), which affects between 1-5 people in 1000 at some point. 7 Seek medical attention promptly.
- Sudden blurred vision or loss of sight or in one or both eyes could be a sign of a stroke. If sudden vision loss is accompanied by numbness in the limbs, a ‘fallen’ face on one side, confusion and difficulty speaking, call 999.
Is sudden blurred vision an emergency?
Blurred vision and dizziness should receive prompt medical attention.
Sudden blurred vision or loss of sight or in one or both eyes could be a sign of a stroke. If sudden vision loss is accompanied by numbness in the limbs, a ‘fallen’ face on one side, confusion and difficulty speaking, call 999. 8
Is blurred vision a sign of diabetes?
The blood sugar changes associated with diabetes can cause blurred vision. In diabetic people, when the blood sugar level elevates too high, fluid in the eye can swell slightly around the lens causing temporary blurred vision. This can be in one, or both eyes.
Very low levels of blood sugar can have the same effect. 9
Is blurred vision a sign of heart problems?
Blurred vision can be a sign of cardiovascular problems.
Clots made from cholesterol deposits lining arteries can become loose in the bloodstream and make their way to the retinal artery, blocking blood flow. If you’re experiencing unexplained periods of blurred vision, it might be time to get your cholesterol and blood pressure checked. 10
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Last updated: 14th December 2020
Expertly reviewed by:
Author: Bhupesh Panchal, Regulatory Affairs
- Joined Holland & Barrett: April 2019
- Qualifications: Masters Degree in Toxicology, BSc Hons in Medical Biochemistry
Bhupesh started his career as a clinical toxicologist for Public Health England, advising healthcare professionals all around the country on how to manage clinical cases of adverse exposure to supplements, pharmaceuticals, cosmetics, industrial chemicals and agricultural products. After 7 years in this role and a further year working as a drug safety officer in the pharmaceutical industry, Bhupesh joined Holland & Barrett as a Senior Regulatory Affairs Associate in 2019.
Bhupesh specialises in vitamins & minerals nutrition, health benefits & safety of botanicals and traditional herbal medicines. View Bhupesh's LinkedIn profile.
In his spare time, Bhupesh likes to cycle and has been learning to speak Korean for several years.