Eye Histology

Question 1

anterior compartment

Answer 1

contains the anterior and posterior chambers separated by iris
filled with aqueous humor

Question 2

posterior compartment

Answer 2

posterior 2/3

contains vitreous humor (with proteins and hyaluronic acid, hyalocytes)

Question 3

coreo-scleral layer

Answer 3

fibrous tunic that makes up globe of the eye (makes up sclera)
where EOM insert, conjunctiva

high collagen and elastin

nearly avascular

Question 4

Uveal layer

Answer 4

vascular layer, contains the iris, highly pigmented, contains blood vessels

Posterior: called choroid
Anterior: cilliary body (contains smooth mm. for accommodation)

Question 5

Conjunctiva

Answer 5

stratified columnar epithelial extension of the sclera

lines the anterior surface of eyeball and inner surface of eyelid

contains mucus secreting goblet cells

Question 6

cornea

Answer 6

transparent in the anterior eye

avascular, highly innervated

5 layers

Question 7

5 layers of cornea

Answer 7

1) outer epithelium (NK Squamous)
2) Bowman’s membrane (basal lamina)
3) Substantia propria: dense collagenous tissue with keratinocytes (allows tissue to remain clear)
4) Descemet’s membrane: thick BL (attachment for corneal epithelium)
5) Corneal endothelium

Question 8

Corneal endothelium

Answer 8

attached to thick basal lamina essential for the movement of nutrients, water, and ions into the cornea from aq humor

important for healing (lots of stem cells)

Question 9

Myopia

Answer 9

nearsightedness
light rays are focused in front of retina
cornea is too curved or lens is too powerful for length of globe

Question 10

Hyperopia

Answer 10

farsightedness

light rays are focused behind the retina, lens and cornea too weak for length of globe

Question 11

LASIK

Answer 11

laser assisted in-situ keratomileusis

for myopia, hyperopia, and astigmatism

goal is to change the shape of the cornea by changing the stroma (substantia propria)

Need to not cut into stroma or Bowman’s membrane

Question 12

choroid

Answer 12

part of the uveal layer
posterior pigmented portion of the vascular layer

loose CT, fibroblasts melanocytes (absorbs any extra light)

Question 13

Bruch’s membrane

Answer 13

separates choroid from retina
basal lamina for pigmented epithelium of retina

controls movement of nutrients and waste

Question 14

choriocapillaris

Answer 14

area next to retina, rich in capillaries

under Bruch’s membrane

Question 15

Drussin

Answer 15

amyloid substance deposited bw bruchs membrane and the retina

age related macular degeneration

impedes flow of nutrients from choriocapillaris

Question 16

ciliary body

Answer 16

wedge shaped structure, forward continuation of the uveal layer

loose CT, muscular tissue, non-pigmented epithelium

ciliary processes are attachment for zonule fibers which attach to lens

Question 17

ciliary processes

Answer 17

important for the filtering of aq humor into posterior compartment (from nonpigmetned fibers)

allow for attachment of zonule fibers

Question 18

accommodation

Answer 18

2 of the 3 bundles

as ciliary mm contract, ciliary body stretches, releasing tension on suspensory ligaments, lens gets thicker and more convex, focuses on nearby objects

Question 19

circulation of aqueous humor

Answer 19

produced by ciliary epithelium lining the ciliary processes

water follows the active transport of ions into the ciliary channel (bw the apical domains of non-pigmented and pigmented ciliary epithelial cells_)

Question 20

circulation of aq humor

Answer 20

enters posterior chamber, passes thru the papillary aperture bw the iris and lens and enters the anterior chamber

drains thru the trabecular meshwork into the canal of schlemm and directly into venous circulation

Question 21

Glaucoma

Answer 21

optic neuropathy resulting in loss of vision due to retinal ganglion cell death

**increased intraocular pressure due to decreased flow thru canal of schlemm into venous drainage

Question 22

corneal irideal angel

Answer 22

Descemets membrane of cornea and anterior surface of iris

allows for flow of aq humor into the canal of schlemm (which forms a complete circle here)

Question 23

open angle glaucoma

Answer 23

NO anatomical obstruction (CI angle is open)

still increased IOP (maybe due to inc production or decreased outflow)
causes slow neurodegenerative processes, optic n cupping

tx: increase outflow or decreasing production

Question 24

angle closure claucoma

Answer 24

CI angle is closed
aq outflow is prevented
primary, congential cause
secondary: due to inflammation, hemorrhage, tumor

**conjunctival redness

Question 25

Iris

Answer 25

colored, anterior extension of ciliary body

controls pupillary aperture

separates anterior and posterior chambers
pupillary zone and ciliary zone (outer circle)

Question 26

histology of iris

Answer 26

NO epithelium
anterior surface is stroma of fibroblasts and melanocytes (pigmentation)

highly vascularized with contractile muscles (sphincter pupillae)

Question 27

lens

Answer 27

transparent, biconvex, avascular

on outside there is a thick, a-cellular capsule

Lens epithelium on anterior ONLY

Question 28

lens fibers

Answer 28

elongated fibers (from epithelium) 
shape and components depend on location on position 

anteriorly, they are long, a-nucleate sacks of crystalline proteins which allows for transparency based upon their solubility

Question 29

cataract

Answer 29

leading cause of blindness

lens does not shed non-viable lens fibers-NO APOPTOTIC MECHANISM (become more compact as we age)

Related to oxidative injury (ETOH, sunlight, hyperglycemia….)

tx: surgical replacement with synthetic intraocular lens