Well, no, sun can not affect the eye color. Generally speaking, the eye color will not change, and it will just be the same as the color you have before. On the other hand, there are also some reasons which can change your eye color. Such as emotion can be the important factor. You should know that when you are sad, your eye color will turn to light blue. Also, weather can affect it too. but there is nothing to do with the sun.
Yes, the sun can affect your eyes color although the eye color is determined by the genetic endowment. However, your eye color can be changed with the appearance of the eyes problems. When you have the eye diseases or other problems in the body health, you could find that your eyes may change the color. For example, when your eyes become yellow, you may have the problems in liver. When the sun shines your eyes too much which may cause your eyes become red, you will find that your eyes become uncomfortable and get the infection. Then the color of the eyes may change the color. You'd better wear the sunglasses under the sun which could protect your eyes from the uv rays and other strong lights.
Ok, it seems that you are quite curious about it. Anyway, I should tell you that the color of our eyes could not be changed in a natural way because it is decided before we came to this world. Exposing eyes to sunshine would affect our pupils to change size but our eye color remain the same. Anyway, our eye color has something to do with our genes , our race and the type of our chromosome. Just take it easy, try to wear sunglasses to protect your eyes in a sunny day.