Overview:
- The human eye is a remarkable sensory organ capable of receiving visual images & relaying them to the brain.
- The eye is protected within a bony socket called the orbits
Besides the eyes, the orbits host several structures, that support the eyeballs including muscles, vessels, nerves & a gland.
- Main eye structures:
- 1. Cornea - transparent tissue at the front of the eye.
- 2. Iris
- 3. Lens
- 4. Retina
- 5. Optic nerve
- 6. Extraocular muscles.
Development:
- Ectoderm
- Neural tube
- Forebrain
- midbrain
- hindbrain
- At 22-days eyes appear as a pair of shallow grooves on the side of the forebrain (optic vesicles)
- As the optic vesicles extend toward the surface ectoderm:
- the proximal portion constricts to form the optic stalk (which becomes the future optic nerve).
- the distal portion invaginates to form the optic cup
- * development of individual structures:
- Lens: the lens vesicle forms through interactions between the optic vesicle & the overlying surface ectoderm
- Cornea, Iris & Ciliary Body: from optic cup & surrounding tissues.