According to WebMD, blurry vision may stem from a number of sources, including an eye injury, nearsightedness or allergies. Hay fever and indoor allergens may also cause blurriness in the vision. Dry eye, pink eye and foreign objects in the eye also cause blurriness.
WebMD names many other possible causes for blurriness in the vision, including astigmatism, glaucoma and farsightedness. While many conditions associated with allergies, such as allergic conjunctivitis, sinusitis and chronic sinusitis, may cause blurred vision, other medical conditions associated with diabetes, including type 1 diabetes, type 2 diabetes, diabetic ketoacidosis and diabetic eye disease, cause blurry vision.
WebMD also attributes eye conditions such as a scratched cornea, irisitis, broken or fractured eye sockets, corneal ulcers, corneal flash burns, macular degeneration, ocular migraine, retinal detachment and contact lens use with blurriness. It also addresses the association of blurred vision with other serious medical conditions, including lyme disease, cryptococcosis, complex partial seizures, simple partial epileptic seizures, multiple sclerosis, stroke, chagas disease, pseudohypoparathyroidism, transient ischemic attacks, low blood pressure and shingles. Abusing the prescription medication benzodiazepines also leads to blurred vision. Optometrist Troy Bedinghaus at About.com also explains that blurred vision may indicate cataracts and uveitis along with the other ocular conditions.