Anatomy of the Eyeball

Three layers of the eyeball

1. Fibrous tunic (outermost layer)

2. Vascular tunic (uvea).

3. Neural layer (inner).

Fibrous tunic (outermost layer)

• Cornea – transparent, anterior.

• Sclera – white, posterior to cornea

Vascular tunic (uvea).

• Choroid

• Ciliary body

• Iris

Neural layer (inner).

Retina – lines posterior two-thirds of eye.

Choroid

pigmented layer behind retina

Ciliary body

ring of smooth muscle around lens

Cilliary muscle

connect to the lens via suspensory ligaments

Cilliary processes

produce aqueous humor

Iris

pigmented diaphragm controlling pupil diameter.

Pupillary constrictor

concentric smooth muscle cells.

Pupillary dilator

spoke-like myoepithelial cells

Anterior Cavity/chamber

• Between iris and cornea

• Filled with watery fluid (aqueous humor)

Anterior Cavity/chamber function

Maintains eye pressure and keeps from drying out

Posterior Cavity/chamber

• Between lens and iris

• Filled with vitreous humor

Posterior Cavity/chamber function

Shapes eyeball and holds retina

Retina

• Contains photoreceptors (rods and cones)

• Innermost layer

Optic disc

- Located in the retina. Point where the optic nerve exits

• Blind spot without photoreceptors.

Macula lutea.

• Central patch for detailed vision.

• Contains cones

• Fovea centralis

• Within macula

• Only contains photoreceptors

• Sharpest vision occurs