2 - Hatcher - Eye Histology

Question 1

Optical Nerve

Answer 1

Cranial Nerve 2

Question 2

Outer Fibrous Layer of Eye

Transition between layers?

Answer 2

Sclera

Cornea

Limbus

Question 3

Middle Layer of eye?

Distinguishing feature?

Answer 3

Choroid

Ciliary Body

Iris

Vascular layer

Question 4

Inner sensory layer of eye?

Answer 4

Retina

Question 5

Sclera

Answer 5

Most superficial layer

Dense connective tissue

Attachment sites for tendons of extraocular muscles

These muscles are under voluntary control!

Question 6

Cornea

Answer 6

Transparent and Avascular

Many nerve endings

Five layers: Corneal epithelium, Bowman’s Layer, Stroma, Descemet’s Membrane, Endothelium

First bending of light

Question 7

What parts of the eye are commonly transplanted?

Answer 7

Cornea

Descemet’s Membrane

Question 8

Answer 8

Question 9

What structure controls movement of water in/out of the stroma?

Answer 9

Corneal endothelium

Question 10

Anterior vs Posterior Cavity

Answer 10

Anterior:

Anterior Chamber - Between Cornea and Iris

Posterior Chamber - Between iris and Lens

Posterior:

Vitreous Chamber (composed of gelatinous mass - Vitreous Body)

Question 11

Ciliary Body

Answer 11

Projection of Choroid and Retina

Includes Ciliary Muscle and Ciliary Processes

Functions: Accomodation and Produce Aqueous Humor

Question 12

Ciliary Processes

What are the two layers?

Answer 12

Attach to lens by Suspensory Ligaments

- - -

Superficial - NOT pigmented

Deep - Pigmented

Question 13

What produces Suspensory Ligaments?

What produces Aqueous Humor?

Answer 13

Superficial epithelial cells in Ciliary Processes

Superficial and Deep epithelial cells in Ciliary Processes

Question 14

What holds the lens in place?

What do these attach to?

Answer 14

Suspensory Ligaments

Attach to Ciliaris Muscle in radial fashion

Question 15

Accomodation for Distant Vision

Answer 15

Ciliaris RELAXES

Suspensory Ligaments TAUT

Lens STRETCHED FLAT

= Distant Vision

Question 16

Accomodation for Close-Up Vision?

Answer 16

Ciliaris CONTRACTS

Suspensory Ligaments RELAXES

Lens BULGED

= Near vision

Question 17

Where do ciliary processes secrete aqueous humor?

How does aqueous humor flow to the anterior chamber?

What is the fate of excess aqueous humor?

Answer 17

Into the posterior chamber

Flows via the pupil

Resorbed via the scleral venous sinus

Question 18

Glaucoma

Answer 18

Elevated eye pressure due to Aqueous Humor being produced faster than absorbed.

Can eventually lead to blindness

Question 19

Iris

Answer 19

Extension of ciliar body, controls amount of light entering eye

Anterior surface has no epithelial cells, posterior surface has two layers of pigmented cuboidal epithelilal cells

Stroma contains myoepithelial cells (dilator muscle)

Question 20

What major structures does the stroma contain?

Answer 20

Melanocytes

Fibroblasts

Myoepithelial cells (dilator muscle)

Blood vessels

Question 21

Lens

Answer 21

Focuses light onto retina

Zonular fibers attach lens to ciliary body

Outer capsule similar to a basement membrane, epithelial cells on anterior surface

Question 22

Lens Fibers

Answer 22

Derived from lens epithelium

Concentric layers of cells, lose nuclei and organelles toward center of lens

Packed with crystallins

Question 23

Main light benders of eye?

Answer 23

Cornea

Lens

Question 24

Rods vs Cones

Answer 24

Rods:

Many more

Night vision

Monochromatic

Cones:

Less

Day vision

Red, Green, Blue

Concentrated in fovea centralis

Question 25

Answer 25

Question 26

Fovea Centralis

Answer 26

Located lateral to **optic disc** Area of **highest visual acuity (Cones high)**

Question 27

Development of Eyes

Answer 27

Optic vessicles bulge from developing **forebrain** and extend as **optic stalks** Optic Vesicle induces **ectoderm to invaginate and detach--forming precursor of lens** Optic Vesicle differentiates into **Optic Cup,** w/internal and external layers, which contribute to neural and pigmented layers of **retina**

Question 28

Formation of Sclera Formation of Cornea

Answer 28

Surrounding mesenchyme forms the **sclera, choroud, and vitreous** Cornea forms from **surface ectoderm**