Whether the heterochromia will last forever depends on the cause of it. Heterochromia can be caused by heredity, genetic mosaicism, chimerism, disease, or injury. In the case of heredity, people are born with different colored eyes. This is congenital, so it can't be cure and will last forever. If it is acuried, it can be cure with medicines.
In order to treat your heterochromia, you should have to take the surgery which could fully help you cure it. As a kind of abnormalities in the body, heterochromia refers to two iris of the eye which presents the character of different color. As we know, the eye color of the iris is determined by iris pigmentation and distribution of the organization. There is no doubt that the formation of any pigment distribution of the above factors could cause different eye color. There are two kinds of heterochromia. One is two different colors of the eyes. Let's take one example, one eye is black, the other one is blue. The second situation is that one eye shows two different colors. Some people getting this are born to be which is determined by their iris. This heterochromia is a genetic disorder which will last forever except from the surgery. However the after period damage of iris will also cause the heterochromia.
It should be considered into two ways:
On the one hand, it can be inherited with born which is mainly because the color of iris is controlled by gene.Or it may be relevent to Piebald Syndrome or Waardenburg Syndrome.The lack of pigment of iris can also explain it.
On the other hand, it can be required by having Horner Syndrome or other diseases that can hurt the iris and cause it to wither.
For my advice, you can choose the eye droppings treatment to control the inflammation. Pranoprofen eye drops will work well. And if it is possible, you can inplant the artificial lens to get a better reslut.
Hope that will help.