How can scientists learn about the evolution of eyes, given that there is very little fossil evidence?

The evolution of the eyes has attracted significant study with the study with the eye distinctively it is difficult to estimate the rate eye evolution becausethe fossil
record particularly of the early

Eyes are critical because, for the 'vast majority of animals', vision is their 'most ... Natural selectionshould, under many circumstances, favor the increments. ... The oldest eye in the fossil record, that of a trilobite, is a very complex faceted ... eye, and in particular the lens, has changed very little during the course of evolution.