Dry Eye Syndrome: This condition is very common and can cause sudden blurring of vision due to insufficient lubrication of the eyes. It's often related to environmental factors, prolonged screen time, or certain medications.

Conjunctivitis: An inflammation or infection of the outer membrane of the eyeball and the inner eyelid. It can cause blurred vision, redness, and discharge.
Uveitis: Inflammation of the uvea, the middle layer of the eye, which can lead to sudden vision loss if not treated promptly.
Migraine: Visual auras associated with migraines can cause transient blurring of vision, often accompanied by headache and other neurological symptoms.
Floaters: Sudden onset of floaters, especially if accompanied by flashes of light, can indicate a retinal tear or detachment, though the primary symptom is usually the perception of floating spots rather than blurring.

Retinal Detachment: A medical emergency where the retina separates from the back of the eye. Symptoms include sudden blurred vision, flashes of light, and an increase in eye floaters.
Stroke or Transient Ischemic Attack (TIA): Sudden vision loss in one eye can be a symptom of a stroke or TIA, especially if accompanied by other neurological deficits.
Acute Angle-Closure Glaucoma: A sudden increase in intraocular pressure can cause severe eye pain, blurred vision, headache, and nausea. It's an emergency requiring immediate treatment.
Optic Neuritis: Inflammation of the optic nerve, which can cause pain and sudden vision loss, often associated with multiple sclerosis.

Pituitary Apoplexy: A rare condition where a pituitary tumor suddenly hemorrhages or infarcts, leading to acute symptoms including sudden vision loss.
Ocular Malignancies: Certain eye cancers, like choroidal melanoma, can cause sudden changes in vision, though this is less common.
Toxic or Medication-Induced Vision Loss: Certain substances or medications can cause sudden vision changes, including blurred vision, as a side effect.