There are many different eye problems and conditions that can cause blurred vision. These include:

Refractive errors

To understand how refractive errors cause blurred vision, it first helps to understand how the eye works. Refractive errors that cause blurred vision include:

• Long-sightedness: causes blurred vision when viewing objects close up, such as when reading a book or using a computer.
• Short-sightedness: causes blurred vision when viewing objects at a distance, such as when watching television or driving.
• Astigmatism: causes blurred vision when viewing objects at any distance, from reading and computer use to driving and watching television.

Other eye conditions that can result in blurred vision:

• Cataracts: Cataracts are a clouding of the lens in your eye. At first, any blurred eyesight may be almost unnoticeable. However, cataracts can eventually result in severe blurred vision that has a major impact on your independence. If you have had a cataract removed and your blurry vision re-occurs, posterior capsule opacity – also known as a ‘secondary cataract’ – may be the cause. This is easy to treat.
• Diabetic retinopathy: Diabetic retinopathy is a condition associated with diabetes. High blood sugar levels cause damage to the retina (the focusing surface at the back of the eye). The final stage of diabetic retinopathy, known as macular oedema, can cause blurred vision.
• Epiretinal membrane: An epiretinal membrane is a thin, fibrous layer that forms over the retina (the focusing surface at the back of the eye). It acts like a film that partially blocks the light entering your eye, which results in blurred vision.
• Keratoconus: Keratoconus is an eye disease that results in a conically shaped cornea (the clear, front window’ of your eye). Because the cornea does much of the eye’s focusing, the irregular shape can cause blurred vision.
• Macular degeneration and macular holes: The macula is the central part of the retina at the back of your eye. It allows you to see detail, colour, and things directly in front of you. Macular degeneration and macular holes damage the macula, causing central vision to become blurred.
• Retinal detachment: A detached retina is a serious medical emergency that can cause sudden blurred vision. It may also cause several other symptoms, such as flashes and floaters and sudden blindness.
• Retinal vein occlusion: If the blood vessels that feed the retina (the focusing surface at the back of the eye) become blocked, it is known as retinal vein occlusion. This can cause sudden blurred vision and also sudden blindness.
• Pterygium: A pterygium is a benign growth that occurs on the surface of the eye. Sometimes, a pterygium can grow onto the cornea. If this occurs, it can alter the shape of the cornea, causing blurred vision.
• Vitreous haemorrhage: If blood leaks into the vitreous ‘gel’ that fills your eye, it can block the light that enters your eye, causing blurred vision. Vitreous haemorrhage can be caused by trauma or injury, or it may result from an eye condition, such as diabetic retinopathy.

Eye infection, inflammation or injury: Many people suffer blurry vision due to an eye infection or injury. Eyelid and eyelash problems can sometimes cause blurred vision, as can the common eye infection conjunctivitis.