"The eye is unique, both as a membrane-enclosed outgrowth of the brain... ''
Ionic control of ocular growth and refractive change. Sheila G. Crewther, Helena Liang, Barbara M. Junghans and David P. Crewther. PNAS October 17, 2006 vol. 103 no. 42 15663-15668
From a developmental perspective the eye is an outgrowth of the brain. During fetal development small patches on the outside of the embryo develop into the two eyes.
