The colors of eyes do have a certain relation with the vision, but not in a decisive way. The eye color depends on the color of the iris, and different colors possess different degrees of ability to absorb the light rays as well as the different amount of energy contained in the light rays. Generally speaking, the deeper the eye color is, the more light and energy the eyes can absorb. Therefore, people with black eyes have the best ability to screen off and adjust the light rays, while people with blue eyes are worse at it, thus blue-eye people has higher rate of getting cataracts than black-eye people do. Therefore, to some extent, people with brown eyes can see better in the sun than people with blue eyes.