Galen refined some of the anatomical mistakes of that time including the curvature of the cornea and lens, the nature of the optic nerve, and the existence of a posterior chamber.
This model was a simplistic version of the eye, but did contain some errors. The ciliary body was found and the sclera, retina, choroid and cornea were correctly recognized. He mistakenly counted 7 optical muscles, but despite his mistakes, this model was not improved upon until after Vesalius in the late 1500s.