Other causes of blurry vision
There are a few other things which can cause blurry vision.
Refractive errors (short-sightedness or long-sightedness)
If your vision is always blurry at long distances, or for close reading, you may be short-sighted or long-sighted, needing glasses to help your eyes focus. This could also be a sign of astigmatism, which is where your eye is curved irregularly.
Refractive errors can be worse when you’re tired. If you have blurry vision at night, this could be the cause.
If you already wear glasses or contact lenses, it might be that your vision has changed or become worse, and you need a new prescription.
If you find yourself struggling with short or long-sightedness, you should visit your optometrist for an eye test. This way, we can help you find out what kind of glasses you need.
UV damage (photokeratitis)
Sudden blurry vision can be caused by damage to your eyes from the sun’s UV rays, almost like sunburn on your eye. This is also called photokeratitis. Fortunately, like skin sunburn, it usually heals within a few days.
Stye or chalazion
Sometimes, a lump on your eyelid can cause blurry vision. This lump could be a stye (which is caused by an infection in your eyelash follicles or the oil glands in your eyelid) or a chalazion (which is caused by a blockage in the oil glands). If it’s large enough to press against your eyeball, it can cause blurry vision. Styes and chalazia are usually not serious. They can be treated using a warm compress and by cleaning and massaging your eyelid using an eyelid scrub or a gentle eye cleanser like Optase. If they last a long time or are particularly troublesome, you should see your optometrist or doctor. They can give you medication or surgery to help treat them.
If your eyes are too dry, this can also cause blurry vision.² There are many causes of dry eyes, including:
- Wearing contact lenses
- Looking at screens for a long time
- Air conditioning or heating
- Windy, dry or dusty environments
- Drinking alcohol
- Side effects of some medicines
- Certain medical conditions, like Sjögren's syndrome or lupus.
If you find you have dry eyes or blurry vision in the morning when you first wake up, it could be because your tears are drying on your eyes during the night. This can be caused by sleeping with contact lenses in, sleeping with a fan on, or even an allergy to something in your bedroom, such as dust mites.⁸
Dry eyes can be treated using lubricating eye drops (artificial tears). Also, trying to find and remove the cause can help, such as taking breaks from screens, swapping contact lenses for glasses and cutting down on smoking and alcohol.
Damage to your retina
Your retina is the layer of cells at the back of your eye which detects light. The macula is the central part of the retina, which allows you to have fine, detailed vision, enabling you to read. Sometimes, problems with your retina or macula can cause blurry vision. These include:
- retinal tears (holes in the retina)³
- macular holes⁴
- retinal detachment (when the retina comes loose from the back of your eye)³
- macular oedema (a buildup of fluid in the macula, often caused by diabetes)⁵,⁶.
Besides blurred vision, if you have a macular hole or macular oedema, you may notice that straight lines look wavy. You may also notice black or dark spots in your vision.4,5,6 If you have a detached retina, this can cause a sudden increase in eye floaters, flashing lights, or a dark shadow moving across your field of vision.³
These problems are serious and can lead to vision loss. If you notice any of these symptoms, you should talk to your optometrist or doctor right away.³,⁴,⁵,⁶
Other eye problems
Blurred vision can also be caused by other eye problems, such as:
- iritis (inflammation of your iris, the coloured ring at the front of your eye)⁷
- keratoconus (distortion in the shape of the cornea, the layer at the front of your eye)⁹
- glaucoma (damage to the optic nerve that can be caused by high fluid pressure in your eyes),