The eye appears during the 3rd week of development as a lateral evagination of the diencephalon, the optic groove.
It gives rise to the optic vesicle, which is attached to the diencephalon by an optic stalk. The optic vesicle grows laterally and comes into contact with the surface ectoderm, inducing its thickening known as the lens placode. This placode subsequently invaginates and develops into the lens vesicle.
The lens vesicle induces the optic vesicle to become invaginated into a double layered optic cup.

The inner layer of the optic cup develops into the neural retina, while the outer layer becomes the pigmented retina. The two layers are temporarily separated by the intraretinal space, which is continuous with the lumen of the brain. Up to the 3rd month, the neural retina has two layers: a nucleated layer and a region of cell processes. Subsequently, the posterior part of the neural retina develops into specialized neurons (rods and cones, bipolar and ganglion cells) and supporting cells forming the pars optica retinae. The optic stalk develops into the optic nerve. Anterior part of the inner layer, pars caeca retinae, remains as single cell layer. It gives rise to the pars ciliaris and pars iridica retinae.

1. Pars optica retinae
2. Neural layer
3. Pigment layer
4. Pars caeca retinae
5. Intraretinal space
6. Ciliary process
7. Pars ciliaris retinae
8. Sphincter pupillae
9. Pars iridica retinae
10. Mesenchyme