Etiology of Blurred Vision The most common causes of blurred vision (see table Some Causes of Blurred Vision) include Refractive errors (the most common cause overall) Age-related macular degeneration Cataracts Diabetic retinopathy Blurred vision has 4 general mechanisms: Opacification of normally transparent ocular structures (cornea, lens, vitreous) through which light rays must pass to reach the retina Disorders affecting the retina Disorders affecting the optic nerve or its connections Refractive errors Table Certain disorders can have more than one mechanism.