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Your autonomic nervous system is the part of your nervous system that controls involuntary actions, such as the beating of your heart and the widening or narrowing of your blood vessels. When something goes wrong in this system, it can cause serious problems, including:

• Blood pressure problems
• Heart problems
• Trouble with breathing and swallowing
• Erectile dysfunction in men

Autonomic nervous system disorders can occur alone or as the result of another disease, such as Parkinson's disease, alcoholism and diabetes. Problems can affect either part of the system, as in complex regional pain syndromes, or all of the system. Some types are temporary, but many worsen over time. When they affect your breathing or heart function, these disorders can be life-threatening.

Some autonomic nervous system disorders get better when an underlying disease is treated. Often, however, there is no cure. In that case, the goal of treatment is to improve symptoms.

NIH: National Institute of Neurological Disorders and Stroke

Some eye problems are minor and don't last long. But some can lead to a permanent loss of vision.

Common eye problems include:

• Refractive errors
• Cataracts - clouded lenses
• Optic nerve disorders, including glaucoma
• Retinal disorders - problems with the nerve layer at the back of the eye
• Macular degeneration - a disease that destroys sharp, central vision
• Diabetic eye problems
• Conjunctivitis - an infection also known as pink eye

Your best defense is to have regular checkups, because eye diseases do not always have symptoms. Early detection and treatment could prevent vision loss. See an eye care professional right away if you have a sudden change in vision, if everything looks dim, or if you see flashes of light. Other symptoms that need quick attention are pain, double vision, fluid coming from the eye, and inflammation.

NIH: National Eye Institute