An eye is a light sensitive structure that generally requires a brain to process the signals. This is because the eye is generally used as a way of finding food or evading predators.

A plant doesn’t move so it can’t evade predators and only needs to know which direction the sun is coming from so an eye would be an expensive organ to develop and own. However a plant can “see/sense” which way the sun is coming from and adjust itself in that direction or “curl up at night” so in a some form a plant must be able to “see light” even though it doesn’t have an organ we would recognise as an eye.