The globe is a spherical biologic camera with an elaborate autofocus lens derived from surface endoderm and a light-absorbing film plate (retina) created by an outgrowth of specialized neurons from the brain. All the surrounding structures are simply there to ensure optimal function of the cornea, lens, and retina.
Specific diseases of the cornea, uvea, and retina are distinct. Diseases affecting the entire eye are uncommon.
The globe is a sealed, fluid-filled sphere protected by the thick fibrous outer shell of cornea and sclera, and a series of vascular & epithelial tight junctions within the uvea and retina.
uvea ((vascular tunic))
•iris, ciliary body and choroid.