Iris (Definition) The iris is a structure within the eye that helps reduce the amount of light that reaches the retina. The iris is known as the colored part of the eye, and can be blue, brown, or any color or combination of colors in between. The iris is the portion of the eye that responds to light stimulation. ...Read more.
Scientists also speculate that caffeine may provide a mood-boosting effect that helps ease pain. Regardless of the mechanism by which it works, the data does indicate that caffeine does indeed make pain medications more effective and help ease pain.
Key Points. 1  Caffeine affects pain. 2  Acute treatment of headaches with caffeine is sometimes effective, but should be limited to not more than two days per week. 3  For people who experience migraine, caffeine taken three or more days per week, for whatever reason, may lead to dependency and increased migraine frequency.