What Causes Blurry Vision?
Unless you’re living with vision loss, you probably rely extensively on your ability to see clearly. So, when something happens that affects your vision, it can be a worry, especially if it’s a long-lasting problem or it happens often. One of these things is blurry or blurred vision.
Blurry vision is when what you see is fuzzy, unclear or out of focus and it is very common. It can affect one eye or both and may alter just part of what you see or your entire field of vision. You may find your vision blurs when you’re looking at objects close up, or that things far away look hazy. And you may also find yourself squinting or rubbing your eyes a lot.
In most cases, however, it isn’t usually anything to worry about, and could simply mean you need to start wearing glasses (or that your current glasses or contacts prescription should be updated). Sometimes, however, blurry vision can be a sign of a more serious problem.
There are numerous things that can lead to blurry vision. To help you find out what’s causing your problem, here’s what you should know.
If your eye prevents light from focusing directly on the retina – the area at the back of the eye that converts light into signals that are sent to the brain – it means you have a refractive error. Refraction is the bending of light as it passes through one object to another. The most common types of vision refractive errors are:
Presbyopia (a condition affecting people aged 40 and older that makes focusing on close objects difficult)
Astigmatism (when your eye cannot focus light evenly onto the retina)
If you have myopia, for example, your vision becomes blurred when you try to see objects at a distance. Hyperopia, on the other hand, causes blurred vision when you view things close up (when reading, for example). In both cases – and also if you have presbyopia or astigmatism – blurry vision can be corrected by wearing glasses or contact lenses (in the case of presbyopia, you’ll usually need to use glasses for reading and close work).
Meanwhile, if you wear contact lenses, your optician should have advised you how long you should keep them in your eyes (usually up to 10 or 12 hours a day if they’re disposable lenses). If you regularly wear them for longer than prescribed – and especially if you sleep with your lenses in – it can make your eyes more susceptible to vision-blurring infections and corneal ulcers, because debris from your tear film can start building up on the lenses and cause problems on the surface of your eye.
Some of the other things that can often cause blurry vision include the following eye conditions:
Dry eye syndrome
If your eyes are persistently dry and uncomfortable, your vision may also become blurred. Dry eye syndrome is a result of having too little tear fluid to keep your eyes lubricated (or no tear fluid at all). And besides blurriness, you may experience other symptoms such as eye irritation and a gritty, itchy or burning sensation.
Dry eye syndrome becomes more common as you get older. However, there are many other causes, including eye strain and not blinking enough as a result of spending too much time looking at a computer or other type of digital screen.
Floaters are tiny spots or specks that drift around your field of vision and become more common with age. Caused by microscopic particles of tissue in the gel-like substance inside your eye (the vitreous) floating freely and casting tiny shadows on the retina, these spots, which are usually harmless, can sometimes cause blurred vision.
Floaters can be irritating but in most cases they fade and become less noticeable over time. If, however, you notice a lot of new floaters in your eye all of a sudden, see your GP or optician, as this could be a sign of an eye condition such as a detatched retina.
Eye infections such as uveitis, conjunctivitis and herpes eye infections can all cause blurry vision. With each of these you may experience other symptoms, including eye redness and watery eyes. Conjunctivitis doesn’t usually require any treatment other than drops called artificial tears to soothe irritation. But if you have a herpes eye infection or uveitis you should see your GP or eye doctor immediately, as early treatment helps reduce the risk of complications.
Find out more about these and other eye infections by reading our article Signs, Symptoms and Treatments of Common Eye Infections Explained.
A cataract is when the lens in your eye becomes cloudy, causing blurred and unclear vision. They can develop very gradually, which means you may not notice any change in your vision at first. Cataracts are common in older people, with around a third of those aged 65 and older thought to be affected by them. The only treatment is surgery to remove the cloudy lens and replace it with an artificial one. If untreated, however, cataracts can cause blindness.
Blurry vision is also a symptom of glaucoma, a group of eye diseases that damage the optic nerve, causing peripheral vision loss. Again, it’s a condition that’s most common in older people, especially those with a family history of the disease and people with diabetes or high blood pressure.
Other symptoms caused by glaucoma include seeing halos around bright lights. If you’re concerned about glaucoma, see your optician for an eye examination as the condition can often be treated with eye drops.
Age-related macular degeneration
AMD affects an area within the retina called the macula, which is important for vision as it allows you to see fine details and colours. If the macula becomes damaged, it can cause symptoms such as blurring of the central part of your vision as well as visual distortions, sensitivity to light and seeing straight lines as wavy or fuzzy.
As its name suggests, AMD becomes more common with age. The most common type – dry AMD – cannot be treated but develops very slowly, causing a gradual change in your central vision. The other type – wet AMD – can develop quickly, causing problems with your central vision in days or weeks. However, there is a treatment for wet AMD that may help prevent any further damage to your sight.
This is a complication of diabetes that affects the retina, making your vision blurry and cloudy. It’s more common in people who have had diabetes for a long time, or those with diabetes who have persistent high blood glucose, high blood pressure or high cholesterol. People with diabetes should have regular diabetic eye screening, which is designed to pick up the signs of diabetic retinopathy as early as possible.
What other conditions cause blurry eyesight?
Besides problems affecting the eyes, there are several other causes of blurry vision, including the following:
Pregnancy (blurry vision can be caused by hormone changes during pregnancy, though vision changes can also be a sign of more serious pregnancy problems such as pre-eclampsia or gestational diabetes)
Retinal migraine (also called ocular migraine, this can cause partial or total loss of vision in one eye that lasts up to 20 minutes, often starting with blurred or dimmed vision, and sometimes also a headache before, during or after the vision attack)
Multiple sclerosis (blurry vision can sometimes be an early sign of MS)
Parkinson’s disease (as this condition progresses it can affect vision, making your eyesight less sharp)
Stroke (blurry vision or double vision can be one of the main signs of stroke)
Some eye drops and medicines may also cause blurry vision (check with the list of side effects on the patient information leaflet that comes with your medication)
How to prevent blurry vision
Tackling the underlying cause of your blurry vision may help improve it as well as prevent it in the future. For instance, the most common treatment for blurry vision is prescription glasses or lenses to treat a refractive error.
If you have dry eye syndrome, on the other hand, you could try using artificial tears to moisten your eyes or take a natural supplement that may help make your eyes feel more comfortable, such as sea buckthorn oili or fish oilsii. Read our article Dehydration and Eye Health: How to Prevent Dry Eyes for more suggestions.
Taking steps to prevent eye conditions that can lead to blurry eyesight is also advisable. For example, if you smoke, quitting may reduce your risk of developing conditions such as AMD and cataracts (according to the RNIB smoking doubles your chances of losing your sightiii
Most importantly, always try to have an eye test as regularly as your optician recommends, as having your eyes checked could help diagnose any potential problems early, which means they may be treated more effectively. Even if your next eye examination isn’t due, see your GP or optician if you’ve noticed any changes in your vision, including blurriness that doesn’t go away or if it happens frequently.
Want to find out more about your vision and what other problems could affect your eyesight? Take a look around our Vision Health Hub for lots more advice and tips.
Larmo, P.S., Jarvinen, R.L., et al. Oral sea buckthorn oil attenuates tear film osmolarity and symptoms in individuals with dry eye. J Nutr. 2010 Aug ;140(8):1462-8 Available online: https://www.ncbi.nlm.nih.gov/pubmed/20554904
Rahul, B., Prachi, K., et al. A randomized controlled trial of omega-3 fatty acids in dry eye syndrome. Int J Opthalmol. 2013;6(6):811-816. Available online: https://www.ncbi.nlm.nih.gov/pubmed/24392330
Disclaimer: The information presented by Nature's Best is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications.
Christine Morgan has been a freelance health and wellbeing journalist for almost 20 years, having written for numerous publications including the Daily Mirror, S Magazine, Top Sante, Healthy, Woman & Home, Zest, Allergy, Healthy Times and Pregnancy & Birth; she has also edited several titles such as Women’ Health, Shine’s Real Health & Beauty and All About Health.