What are causes of having cloudy vision and seeing halos?

Need a diagnosis: Cloudy vision and halos can generally be caused by anything that interferes with light entering the eye, including hazy glasses or contact lenses. However, cataract is a common cause of this, and a less common cause is a scar of the cornea. Corneal swelling (edema) typically causes a rainbow type of halo, and this can be more serious, as it can occur with greatly elevated eye pressure.