Potential causes of instant blurred vision include macular holes in the retina, glaucoma, strokes and multiple sclerosis, according to AllAboutVision.com. Any patient experiencing sudden-onset blurred vision should seek immediate medical attention, as it can be a symptom of a medical emergency.
Instant blurred vision from a macular hole in the retina usually occurs in patients over age 60 and only affects one eye, notes AllAboutVision.com. The symptom arises when the hole forms in the area of the retina responsible for fine focusing. Glaucoma causes the visual field to narrow and the edges of the patient's field of view to grow blurry. The onset is typically gradual, but the blurring and narrowing of the vision sometimes happens suddenly. Sudden blurred vision due to a stroke sometimes occurs along with double vision.
There are numerous other eye and neurological conditions that cause blurry vision to develop at a less-sudden pace, explains AllAboutVision.com. Refractive errors, such as farsightedness and nearsightedness, are the most common. In the case of farsightedness, objects near the patient's face appear blurry, while nearsighted individuals perceive objects in the distance as blurry. Astigmatism is another common refractive error. It results from an unusually shaped cornea and causes vision to be blurry at any distance.
Some other causes of blurred vision are ocular migraines, wearing contact lenses for too long, dry eye syndrome and hormonal changes during pregnancy, states AllAboutVision.com.