According to research by David H. Hubel and Torsten Wiesel, suturing shut one eye of monkeys at an early age resulted in an irreversible loss of vision in that eye, even after the suture was removed [REF].
While red/green color blindness among deuteranopes can be treated by introducing M-opsin genes, rarer forms of color blindness such as tritanopia can in principle be treated as well.