Eye

Question 1

What are the bones forming the walls of the orbit

Answer 1

Ethmoid
Maxilla
Zygomatic
Lacrimal
Frontal
Sphenoid

Question 2

Why are some aspects of the walls vulnerable to fracture

Answer 2

Sinuses next to floor and medial wall causes weakness

Question 3

What is a blow out fracture

Answer 3

Sudden increase in intra orbital pressure which fractures the floor. This causes prolapse into medullary sinus and tethers the eye from the bottom so cannot look up.

Question 4

Why with a blow out can you get numbness over the cheek, upper lip and eyelid

Answer 4

Disruption to cutaneous nerve Vb

Question 5

Where does the eye get its blood suppy

Answer 5

1st branch of ICA
Ophthalmic artery
Gives off central retinal after going through optic canal and this supplies retina and chorioid layer
Ciliary artery feeds choroid layer.

Question 6

What happens if there is central retinal artery occlusion

Answer 6

Cherry red spot where macula is thinnest as choroid layer is still being perfused by ciliary artery.

Question 7

Why does infection to eye pose threat of spreading

Answer 7

Ophthalmic veins drain into cavernous sinus, pterygoid plexus and facial vein

Question 8

What muscle and nerve closes the eye

Answer 8

CN7 palpable part of orbicularis oculi

Question 9

What muscle and nerve contracts and elevates the eyelid

Answer 9

Levator palpebrae- CN3

Question 10

What is the function of the meibomian gland

Answer 10

Oily substance to prevent evaporation of tear film.

In tarsal plates

Question 11

Function of orbital septum

Answer 11

Barrier against superficial infection spreading pre septal to post septal

Question 12

Where is humour made and when does it go

Answer 12

Maid in ciliary processes in ciliary body. flows posterior to anterior draining through iridocorneal angle via trabecular meshwork into canal of schlemm to venous circulation

Question 13

Where does vitreous humour fill

Answer 13

Intraocular

Question 14

Aqueous humour

Answer 14

fills anterior and posterior chambers providing O2 and nutrients to lens and cornea.

Question 15

What is the function of the lacrimal apparatus

Answer 15

Tear film production and drainage

Question 16

What is epiphora

Answer 16

Overflow due to obstruction of nasolacrimal duct

Question 17

What are the 3 layers of the eyeball

Answer 17

Sclera
Choroid
Retina - innermost layer

Question 18

What is the macula densa

Answer 18

Dense area of photoreceptors- cones for high acuity of colour vision
The thinnest part of retina
Light is focused here

Question 19

What helps refract light

Answer 19

Tear film, cornea, lens and humour

Question 20

What helps regulate light entry

Answer 20

Pupil

Question 21

What causes long sight

Answer 21

Hypermetropic- eyeball to short

Question 22

What causes short sight

Answer 22

Myopic- eyeball to long

Question 23

What is the Accommodation reflex

Answer 23

Eye restricts pupil and converge to stay fixed on same point. Lens becomes biconvex- fatter

Question 24

How does the lens change shape

Answer 24

Contraction of ciliary muscles under parasympathetic oculomotor control leads to fatter. Relaxation means ligaments are pulled tight = lens flattens.

Question 25

What is the fovea

Answer 25

Place with only cones

Question 26

What causes blind spot

Answer 26

Optic disc has no photoreceptors

Question 27

What does pinhole testing do

Answer 27

Sees if there is a refractive error or not

Question 28

Difference between styes and meibomian cyst

Answer 28

Painful, superficial, blocked sebacceous ? staph VS painless blocked meibomian gland

Question 29

What is blepharitis

Answer 29

Inflammation of lids, gritty

Question 30

What is conjunctivitis

Answer 30

Inflammation of conjunctiva viral or bacterial.

Question 31

What are cateracts

Answer 31

Decrease transparency of structures anterior to retina. Decreases refractive ability.

Question 32

What is presbyopia

Answer 32

Lens stiffer with age Less able to change shape Near objects hard to focus on

Question 33

What are the two types of glaucoma

Answer 33

Acute vs Chronic

Question 34

What is the issue in glaucoma

Answer 34

Blockage of drainage of aqueous humour from anterior chamber = increased intraocular pressure.

Question 35

Explain chronic glaucoma

Answer 35

Open angel Trabecular meshwork deteriorates with age Increased intraocular pressure Disc cupping Gradual loss of peripheral vision due to ischemia and damage to optic nerve

Question 36

Explain acute glaucoma

Answer 36

Closed angle Narrowing of iridocorneal angle Emergency Halo- corneal edema

Question 37

What changes do you see in Papilledema

Answer 37

Disc swelling secondary to raised intracranial pressure Bilateral Optic nerve swelling

Question 38

What changes do you see in glaucoma

Answer 38

Disc cupping | Increased cup to disc ratio caused by high pressures in the eye

Question 39

Why do we have binocular vision

Answer 39

Wider field of vision | Depth perception

Question 40

What does misalignment of visual axis cause

Answer 40

Image focuses of different areas of retina. Image cannot be fused = double vision - diplopia

Question 41

What are the extraocular muscles

Answer 41

S,M,L,I rectus | SO and IO

Question 42

What is the origin for all but IO muscle

Answer 42

Apex of orbit

Question 43

Where does the IO muscle arise

Answer 43

Floor of orbital cavity

Question 44

What is the action of the SO

Answer 44

Intort, depress and slightly abduct

Question 45

When is the SO most powerful

Answer 45

Medially

Question 46

What does the IO do

Answer 46

Extort, elevate, abducts

Question 47

When is the IO most powerful

Answer 47

Medially

Question 48

What is the action of S recuts

Answer 48

Elevation, slight adduction, slight intorsion

Question 49

When is S rectus most powerful

Answer 49

Laterally

Question 50

What is the action of I rectus

Answer 50

Depression, slight adduct, slight extort

Question 51

When is I retus most powerful

Answer 51

Laterally

Question 52

Why do we perform a H in eye exam

Answer 52

To isolate muscles to test individually as some share common action but each has a place where it's more dominant

Question 53

What is Stabismus

Answer 53

Ocular misalignment- common in children

Question 54

What is the innervation of LR

Answer 54

CN6

Question 55

What is the innervation of SO

Answer 55

CN4

Question 56

What is the innervation of the rectus and IO

Answer 56

CN3

Question 57

What else does CN3 innervate

Answer 57

Sphincter pupillae muscles and levator palpebrae superioris

Question 58

In compressive lesion is the pupil spared

Answer 58

No, its involved