The primary goal of IPL (Intense Pulsed Light) is to make the skin tone or color more even. One of the signs of aging is irregular brown and sometimes red discoloration of the skin. These changes (called dyschromias) are usually due to sun damage.
The light energy in IPL is absorbed by the colors that we don't like, causing the generation of heat that damages or destroys the structure that holds the color - the sun spot or dilated blood vessel. The body sees the structure as damaged and takes it away. This leaves the skin tone more even and homogeneous.
In addition, IPL brightens the skin and gives it a youthful glow. This is a remarkably consistent result of IPL. For many patients, this alone makes IPL worth the effort.
Another, but more subtle goal of IPL, is to add small amounts of collagen back into the skin near its surface. This will not reduce wrinkles, but it does have an effect on the texture of the skin.
So, a patient can expect 3 things from IPL:
It evens out skin color.
It brightens the skin and give it a youthful glow.
It adds back small amounts of collagen near the surface of the skin to give a slight improvement in texture.
As always, the results are operator dependent.