Eye

Question 1

What are the 3 layers of the eye wall?

Answer 1

1. outer fibrous coat (cornea and sclera)
2. middle vascular coat (iris, ciliary body, choroid)
3. inner retinal coat (retinal pigmented epithelium (RPE) and neural retina

Question 2

How many chambers does the eye contain?

Answer 2

3: anterior between cornea and iris, posterior between iris and lens, vitreous cavity between lens and retina

Question 3

Describe the cornea

Answer 3

transparent, convex shape, avascular (avascular means it can be transplanted without rejection)

Question 4

Where does the cornea receive nutrients?

Answer 4

central part from diffusion through the aqueous humor, peripheral part supplied by blood from limbus vessels

Question 5

List the layers of the cornea (anterior to posterior)

Answer 5

epithelium (non-keratonized strat. squam.)
bowman’s layer (type I collagen)
stroma (type I and V collagen, condroitin, keratan sulfate)
decemet’s membrane (thick basement membrane)
corneal endothelium (impermeable intercellular spaces)

Question 6

What is the sclera made of?

Answer 6

dense irregular CT

Question 7

What is the limbus (of the sclera)

Answer 7

junction between the cornea and sclera (adjacent to the trabecular meshwork and canal of Schlem)

Question 8

Describe the flow of aqueous humor

Answer 8

produced by epithelium in anterior chamber of ciliary body –> trabecular network –> canal of Schlemm –> aqueous veins –> episcleral veins

Question 9

What is glaucoma and what is one cause?

Answer 9

increased eye pressure, may be caused by obstruction of aqueous humor flow at the canal of Schlemm

Question 10

What are the regions of the middle tunic of the eye?

Answer 10

choroid, ciliary body, and iris

Question 11

What are the three layers of the choroid?

Answer 11

Bruch’s membrane (innermost), choriocapillaris, choroidal stroma

Question 12

What are the 2 portions of the ciliary body?

Answer 12

uveal and neuroepithelial

Question 13

What does the ciliary process on the anterior portion of the ciliary body do?

Answer 13

contains epithelium that produce aqueous humor

Question 14

What is the iris? What is it really?

Answer 14

continuation of the ciliary body

Question 15

Describe the muscles on the iris

Answer 15

2 layers of smooth muscle: circular and radial.
constrictor muscle- small pupil size, parasympathetic innervation
dilator muscle- big pupil, sympathetic innervation

Question 16

Describe the lens of the eye

Answer 16

avascular, transparent and elastic, biconvex shape, thick basement membrane material called the capsule

Question 17

What changes the shape of the lens?

Answer 17

suspensory ligament fibers (zonular fibers)

Question 18

What is vitreous humor?

Answer 18

transparent gel-like material made of water and hyaluronic acid. Keeps lens and retina in place

Question 19

What is a cataract?

Answer 19

change in the opacity of lens, symptom of old person disease

Question 20

What are the first 2 layers of the retina (the only ones we need to know)

Answer 20

1. Retinal pigemented epithelium (RPE)- phagocytosis old discs shed from rods, and stores and releases vit. A
2. Layer of rods and cones

Question 21

What are rods?

Answer 21

tall cylindrical cells; low light and peripheral vision; have discs derived from plasma membrane that contain rhodopsin pigment

Question 22

What are cones?

Answer 22

cone-shaped cells; color vision and bright light; have discs and pigments sensitive to red, green, and blue light

Question 23

What cells does the fovea contain?

Answer 23

only cones

Question 24

How are photoreceptors regenerated?

Answer 24

rods shed outer discs which are phagocytosed by the RPE layer, new discs made from below and move upward. Cone discs are replaced more slowly

Question 25

What landmarks would you see on the posterior retina when looking through the pupil with a scope?

Answer 25

macula lutea and optic disc

Question 26

What is the optic disc?

Answer 26

papilla where optic nerve fibers exit retina; doesn’t have any photoreceptors

Question 27

What structure would you see in the center of the macula?

Answer 27

fovea (100% cone cells)

Question 28

What is the macula?

Answer 28

avascular pigmented area in the center of the retina

Question 29

What is a detached retina?

Answer 29

when the neural retina separates from the RPE and choroidal capillaries

Question 30

Describe age related macular degeneration

Answer 30

macular area and fovea lose function because pigment epithelium behind retina degenerates and forms drusen (white spots). Foveal cones die and central vision loss ensues

Question 31

What is glaucoma?

Answer 31

increased pressure in the eye; may compress blood vessels of optic nerve

Question 32

What is retinitis pigmentosa?

Answer 32

hereditary disease; rods of peripheral retina degenerate and patients develop tunnel vision; night blindness is an early sign; black pigments develop in peripheral retina and blood vessels are thinned at optic nerve

Question 33

What is diabetic retinopathy?

Answer 33

blood vessels distort and multiply; treated with lasers

Question 34

What is hereditary retinal dystrophy?

Answer 34

inability of RPE to phagocytize worn out discs from the rods

Question 35

What is the lacrimal gland?

Answer 35

a compound tubuloalveolar gland; secretes tears (tears contain lysozyme)