W6_01 Eye: Anatomy and Physiology

Question 1

what divides the eye into the anterior and posterior segments?

Answer 1

the lens

Question 2

what separates the anterior and posterior chambers?

Answer 2

the iris

Question 3

name structures in the anterior segment of the eye

Answer 3

sclera
cornea
anterior chamber
iris
ciliary body
lens

Question 4

name the perforation in the sclera to allow optic nerve penetration

Answer 4

lamina cribosa; meshwork that allows passage of CN II fibres

Question 5

3 components of the conjunctiva

Answer 5

palpebral
forniceal
bulbar

Question 6

describe episclera vasculature

Answer 6

2 layers: superficial and deep.

deep vessels are larger

Question 7

name two pathologies of the episclera

Answer 7

episcleritis

scleritis (serious; due to rheumatoid arthritis)

Question 8

what’s the division of diopter power in the eye?

Answer 8

cornea: 2/3 (~40D)
lens: 1/3 (~20)

Question 9

3 reasons for transparency within the cornea?

Answer 9

avascularity
uniform structure
deturgescence

Question 10

thickness of cornea?

Answer 10

centrally 0.54mm;

peripherally 1 mm

Question 11

how many layers of the cornea?

Answer 11

5

Question 12

what are the layers of the cornea?

Answer 12

epithelium
Bowman's membrane
stroma
Descemet's (basement) membrane
endothelium

Question 13

difference between cornea and sclera?

Answer 13

collagen is coarse and irregular in sclera, causing opacity

Question 14

components of the lens?

Answer 14

capsule
epithelium
nucleus
cortex

Question 15

types of cataracts?

Answer 15

cortical
nuclear sclerosis (aging)
posterior subcapsular (steriods, diabetes)

Question 16

where can intraocular lenses be implanted?

Answer 16

anterior chamber

posterior chamber

Question 17

components of the uvea?

Answer 17

iris (anterior)
ciliary body (middle)
choroid (posterior)

Question 18

muscles in the iris?

Answer 18

sphincter muscle constricts (cholinergic)

dilator muscle dilates (adrenergic)

Question 19

function of the pars plicata?

Answer 19

producing aqueous humour for the anterior chamber

Question 20

functions of the ciliary body?

Answer 20

production of aqueous humour

accomodation

Question 21

how is aqueous humour drained?

Answer 21

trabecular meshwork to canal of schlem

uveascleral outflow to episcleral venous vessels

Question 22

what attaches the lens to the ciliary body?

Answer 22

zonules

Question 23

how do the lens, ciliary bodies, and zonules change in shape to accommodation?

Answer 23

ciliary body SM contracts; CB moves anteriorly
zonules relax
lens rounds up

Question 24

components of the posterior segment?

Answer 24

vitreous
retina
choroid
optic nerve

Question 25

vitreous pathology?

Answer 25

``` vitreous homorrhage (e.g. diabetics) fungus endophthalmitis ```

Question 26

how big is the optic disc?

Answer 26

1.5mm in diameter

Question 27

what is the macula?

Answer 27

centre of retina; fovea is centre of macula; most detailed vision from here

Question 28

how many layers in the retina? | how many layers does light penetrate to get to rods/cones?

Answer 28

10. light goes through 8 layers to reach rods/cones.

Question 29

choroidal pathology?

Answer 29

choroidal nevus | choroiditis

Question 30

describe the optic nerve pathway and lengths

Answer 30

intraocular (1 mm) intraorbital (25mm) intracannalicular (9 mm) intracranial (16 mm)

Question 31

optic nerve pathology?

Answer 31

optic disc edema | glaucoma

Question 32

7 bones that make up the orbit?

Answer 32

``` frontal sphenoid zygomatic maxillary bone lacrimal bone ethmoid bone palatine ```

Question 33

what passes through the optic foramen? the optic foramen is in which bone?

Answer 33

optic nerve and opthalmic artery; | in sphenoid bone

Question 34

what passes through the superior orbital fissure? the fissure is made from which bone?

Answer 34

CN III, IV, V1, VI, superior opthalmic vein, vessels; | fissure is between greater and lesser wings of sphenoid

Question 35

layers of the tear film?

Answer 35

lipid layer aqueous layer mucin layer corneal epithelium

Question 36

what produces the mucin layer of the tear film?

Answer 36

conjunctival goblet cells

Question 37

what produces the aqueous layer of the tear film?

Answer 37

accessory lacrimal glands (kraus and wolfring)

Question 38

what produces the lipid layer of the tear film?

Answer 38

meibomian gland in lid margin

Question 39

tear pathologies?

Answer 39

dry eye (loss of either layer) blurry vision can be caused by blepharitis

Question 40

lacrimal gland pathology?

Answer 40

congenital lasolacrimal duct obstruction | dacryocystitis