It depends on the cause of heterochromia.
If the heterochromia is inherited, that is, the patient is born with different eye colors, there is no difference in his or her vision but difference in look of his or her eyes.
If the heterochromia is caused by disease or trauma, the answer depends on the influence of the kind of disease on the patient. In this case, heterochromia is curable through curing the disease or trauma.
People with heterochromia will of course see things. They will show the difference at the two colors of the eyes. In order to improve your situation, you could do the surgery to cure it. Or the special eyeglasses will also work. You could base on your own condition to choose the suitable way.
Well, yes, of course, people with heterochromia can just see things, and generally speaking, some reports have shown that people with heterochromia often have different eye colors. But on the other hand, they still watch things well, for there is nothing to do with their vision. For the causes, you should know that the heterochromia can be caused by disease or trauma. And also, it can just be hereditary. So that is why there are some people who are born with it. And to improve it, eye surgery or some kind of eyeglasses can be used.