Systemic diseases are diseases that involve many organs or the whole body. Many of these diseases also affect the eyes. In fact, an eye exam sometimes leads to the first diagnosis of a systemic disease.

Why is the eye so important in systemic disease?

The eye is composed of many different types of tissue. This unique feature makes the eye susceptible to a wide variety of diseases as well as provides insights into many body systems. Almost any part of the eye can give important clues to the diagnosis of systemic diseases. Signs of a systemic disease may be evident on the outer surface of the eye (eyelids, conjunctiva and cornea), middle of the eye and at the back of the eye (retina).

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The optic nerve and eye movements often reflect changes in the central nervous system. This is because a large part of the brain helps provide visual information and controls eye movements. Because the eye structures are uniquely transparent, a doctor can see inside the eye. The eye is the only organ in the body in which a doctor can directly see blood vessels (particularly the small blood vessels and the underlying body tissues in their natural state). The health of the blood vessels (and body tissues) in the eye often indicates the condition of the blood vessels (arteries and veins) (and tissues) throughout the body.

Which systemic diseases most commonly affect the eye?

The eye may be involved in these diseases, among others:

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Diabetes mellitus – an imbalance in blood glucose (sugar) levels. Acquired immunodeficiency syndrome (AIDS) – a life-threatening disease caused by a virus that cripples the body’s immune defenses. Graves’ disease – a thyroid disorder, most often in women, which can cause a goiter (swelling in the front part of the neck) and protruding eyes. Sarcoidosis – a disease that mainly affects the lungs, brain, joints and eyes, found most often in young African-American women. Systemic lupus erythematosus – a connective tissue disorder involving mainly the skin, joints and kidneys. Rheumatoid Arthritis Hypertension (high blood pressure) Atherosclerosis (hardening of the arteries) Sickle cell disease – an inherited blood disorder that can block circulation throughout the body, primarily affectingAfrican-Americans Multiple sclerosis – a disease that damages nerve coverings, causing weakness, coordination and speech disturbances.

See a more detailed review of the importance of examination of the eye in systemic disease at: http://nationalmex.com/file/view/17732/why-the-eye-is-so-important-in-systemic-disease#.VVigpNh0zIU