It is a well-known fact that the universe is expanding. This means that the farther we look in the universe, the farther speed away the objects there are from us.
In this case, based on the Doppler Effect, the frequency of electromagnetic waves will be slide in a lower region.
This means that when you look at to a certain distance with the optical telescope, the colors shift, because of the Doppler Effect. Red going to be yellow, yellow will be green, etc., and magenta slides to UV (Ultra-violet).
It is not a major problem. However the visual will be false.