eye disorders
Blurred Vision
Causes of Blurred Vision
Blurred vision has 4 general mechanisms: Disorders affecting the retina, the light-sensing structure at the back of the eye Clouding of normally transparent eye structures (cornea, lens, and vitreous humor—the jellylike substance that fills the eyeball) that light rays must pass through to reach the retina Disorders affecting the pathways of nerves that carry visual signals from the eye to the brain (such as the optic nerve) Imperfect focusing of light rays on the retina ( Overview of Refractive Disorders ) Certain disorders can have more than one mechanism. For example, refraction (focusing ability) can be impaired by early Cataract or by the reversible lens swelling caused by poorly controlled Some disorders that cause blurred vision are more likely to cause other symptoms that prompt people to seek medical attention, such as Eye Pain and The most common causes of blurred vision include (such as nearsightedness, farsightedness, or astigmatism), which are the most common cause overall Age-Related Macular Degeneration (AMD or ARMD) None None Damage of the retina resulting from diabetes ( Diabetic Retinopathy ) None Astigmatism is an irregularity in the curvature of the cornea or lens. That is, the cornea or lens is curved differently in different directions. This difference causes light traveling in different planes to be focused differently. For example, vertical lines may be in focus when horizontal lines are not (or vice versa). The irregularity can be in any plane, however, and is often different in each eye. A person with astigmatism (each eye should be tested separately) tends to see certain lines more boldly (that is, in better focus) than the others. Astigmatism can be corrected with prescription eyeglasses or contact lenses. It often occurs together with nearsightedness or farsightedness. The diagram below is of a standard chart used to test for astigmatism in one eye at a time. Rare disorders that can cause blurred vision include Inherited disorders affecting the optic nerve, called Hereditary Optic Nerve Disorders (for example, dominant optic atrophy and Leber hereditary optic neuropathy) Corneal scarring due to Vitamin A Deficiency (rare in high-income countries) 