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Pupil

The pupil is the black area in the center of the iris, the colored part of the eye. The iris controls the size of the pupil in response to light outside the eye so that the proper amount of light is let into the eye.

Light passes through the pupil to the back of the eye, where an image is formed of what the eye is looking at.

Decision Points

Our interactive Decision Points guide you through making key health decisions by combining medical information with your personal information.

You'll find Decision Points to help you answer questions about:

Interactive Tools

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Our Interactive Tools can help you make smart decisions for a healthier life. You'll find personal calculators and tools for health and fitness, lifestyle checkups, and pregnancy.

Symptom Checker

Feeling under the weather?

Use our interactive symptom checker to evaluate your symptoms and determine appropriate action or treatment.