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.
Caffeine also wakes up the pain reception in your brain, so yes, it does. But it causes pain in the joints directly too. Yes, there is possibility. As per theory of Ayurveda the disease is in Vaat (wind) category which must increase with drinks like /cola soda containing gas.