Anatomy of the Eyeball

What are the three layers in the walls of the eyeball

fibrous, vascular/uvea, sensory

Fibrous layer and what does it contain

Outermost layer - avascular

sclera and cornea

What is it + what does it do + how does it related to the brain

Sclera of fibrous layer (white of eye)

• protects and shapes eyeball

• where extrinsic muscles attach

• continuous with dura mater of brain posteriorly

what is it - what does it do - what does it have

Cornea of fibrous layer

• Transparent anterior portion

• bends light as it enters eye

• Lots of pain receptors → blinking and tear reflexes

Vascular layer (uvea layer) and what does it contain (3)

middle pigmented layer (blood flow→ vascular)

• iris, ciliary body, choroid

Choroid of vascular layer

• Supplies blood to all layers

Ciliary body of vascular layer

• Smooth muscles (ciliary muscles) that control shape of lens (accommodation)

iris of vascular layer

• colored part of the eye

• controls pupil size in the center of the iris

Pupil → central opening that regulates the amount of light entering the eye

not structure just a hole

What are the 2 muscles of the iris and what does it do and what system is each part of

Sphincter pupillae → constricts the pupil → parasympathetic

dilator papillae → dilates pupil (expand) → sympathetic

Sensory layer and what does it contain

delicate 2 inner layer membrane

retina

Retina of sensory layer

What are the two layers of the retina / sensory layer

Pigmented layer (outer) and neural layer (inner)

Pigmented layer of retina

Outer layer → absorbs light and prevent scattering

Neural layer of retina

Has photoreceptors (rods and cones) that transduce light energy

Detached retina

Neural and pigmented layer becomes separated → disrupts vision

Ganglion cell axons

Run along inner surface of retina → leave the eye as the optic nerve (CN 2)

Optic disc

where optic nerve leaves the eye

blind spot because no photoreceptors

Macula lutea

area of central vision → has lots of cones

center of retina at the back of the eye

Fovea centralis

center of macula lutea → focus → best vision

The lens divide eye into

anterior segment and posterior segment

Anterior segment

In front of the lens

contains aqueous humor (fluids)

divided into anterior and posterior chamber

What is the anterior segment divided into

Anterior chamber - between cornea and iris

Posterior chamber - between iris and lens

Posterior segment - where has what and what 3 functions

Behind the lens

has vitreous humor (fluid)

Transmits light, holds the neural retina to pigmented layer, maintains intraocular pressure

Glaucoma

aquous humor drainage blocked → pressure builds up and compresses retina and optic nerve → blindness

Lens

biconvex (curves both sides - () ), transparent, flexible, elastic, and avascular

What do lens do

allows precise focusing of light on retina

What happens to lens with age

less elastic, dense, and more convex () → I)

Cataracts

lens become clouded