No, you don't. The eyes of a trout produce a significantly different view of the world than the eyes of a fly fisher. The physiology of a trout's eye is different than a human eye and produces different results. Understanding what trout do and don't see will help you catch more fish.

Trout definitely see color. In fact, there is evidence to support that they see farther into both the infrared and ultraviolet spectrum than we do. This is especially true when they are fingerlings and again at spawning time. Because trout see color so well, bright colors such as whites, reds, yellows, pinks, etc., that are not often found in a trout's natural habitat, tend to spook them pretty quickly. Few things will send a trout scurrying for cover quite as quickly as a brightly colored hat, especially in slow-moving clear water.

Trout also have binocular vision in a 30º cone directly in front of them, which allows them to judge distance easily and accurately. They have a blind spot in a 30º cone behind them, and all the rest of the vision could be loosely compared to peripheral vision, which will focus on any detected movement quickly. Because of the blind spot behind them, most trout are more easily approached from the rear. Of course, some trout move side to side just to compensate for this blind spot - they are usually the bigger fish.

Although they have a wide visual range, the acuity of a trout's vision is poor. Even at its best focus point of 2" everything is still a blur. Good thing or they'd probably realize that the hook hanging down from your fly isn't part of a natural food form.

You'll do well to wear clothing and a hat that blends into the background or the sky. Don't silhouette yourself by standing tall. Trout don't have eyelids, so if the sun is bright and you can get it behind you without casting a shadow on the trout, don't hesitate to hide in that glare. Keep low, move slowly, blend into your environment, and you'll be surprised at how many more fish you'll catch.