Blurry vision is one of the most common reasons people visit an optician. While it is often caused by a straightforward need for glasses, blurry vision can sometimes indicate more serious conditions that require prompt attention.
The most common cause of blurry vision is refractive error — meaning your eyes do not focus light correctly. This includes short-sightedness (myopia, where distance vision is blurry), long-sightedness (hypermetropia, where close-up vision is blurry), astigmatism (where vision is blurry at all distances due to irregular corneal shape), and presbyopia (age-related difficulty with close-up focus, typically starting around age 40). All of these are easily corrected with glasses or contact lenses.
Other common causes of blurry vision include dry eye disease (the tear film breaks up and causes intermittent blurriness), prolonged screen use and digital eye strain, cataracts (gradual clouding of the lens, common over age 60), and medication side effects (some drugs list blurred vision as a side effect).
More serious causes that require urgent attention include retinal detachment (blurriness or a shadow spreading across your vision, often preceded by flashes and floaters), acute glaucoma (sudden severe blurring with eye pain, headache, and sometimes nausea), stroke or TIA (sudden blurring or loss of vision, especially in one eye), optic neuritis (blurring with eye pain, sometimes associated with multiple sclerosis), and wet macular degeneration (central vision becomes distorted or blurry).
As a general rule: gradual blurriness that has developed over weeks or months is likely a prescription change and should be checked at a routine eye test. Sudden blurriness that develops over hours or days, particularly in one eye, with pain, or with other symptoms such as flashes, floaters, or headache, should be assessed urgently — call your optician, NHS 111, or attend A&E if you cannot be seen the same day.