The Eye

Question 1

what are the 3 openings into the orbit

Answer 1

superior orbital fissure
inferior orbital fissure
opti canal

Question 2

what goes through the superior orbital fissure

Answer 2

occulomotor nerve, trochlea nerve, trigeminal (ophthalmic) and abducens

Question 3

what are the weakest parts of the orbit and why are they the weakest

Answer 3

the medial wall and floor

this is because they have air cavities next to them instead of bone

Question 4

what is an orbital blow out fracture

Answer 4

where trauma to the orbit causes a fracture of the floor of the orbit

Question 5

what does an orbital blow out fracture result in

Answer 5

swelling, double vision, anaesthesia over the cheeks

Question 6

why is there anaesthesia over the cheeks in a blow out fracture

Answer 6

as the intra-orbital nerve (trigeminal) runs through the floor of the orbit so is damaged

Question 7

what would be seen on a CT/X ray in a blow out fracture

Answer 7

the fractured floor
blood in the maxially sinus
orbital contents in the maxially sinus

Question 8

what are the 2 types of glands found in the eyelid

Answer 8

glands in the tarsal plates and glands at the hair follicles

Question 9

what happens if the glands at the tarsal plates are blocked

Answer 9

you get a meibomian cyst

Question 10

what happens if the glands at the eyelashes are blocked

Answer 10

you get a stye

Question 11

what are the tarsal plates

Answer 11

the fibrous skeleton giving the eyelids firmness and shape

Question 12

what is the orbital septum

Answer 12

it is a separation produced by the tarsal plates and tendon of levator palpebrae

Question 13

what is pre-septal orbital cellulitis

Answer 13

infection in the pre-septal orbit (space between the tarsal plates and the eyelid fat)

Question 14

what is post-septal cellulitis

Answer 14

infection the orbital cavity

Question 15

what does the orbital septum prevent

Answer 15

infection spreading between the pre and post septal orbit

Question 16

what are the complications of post-septal cellulitis

Answer 16

abscess

spreading to the cavernous sinus - this could then potentially spread to the brain

Question 17

what does the lacrimal gland do

Answer 17

produce tears to keep the conjunctiva and cornea lubricated

Question 18

where do tears drain

Answer 18

into the lacrimal punctum - this then goes through the lacrimal sac to the nasolacrimal duct

Question 19

what does the conjunctiva do

Answer 19

produces a mucus covering to help lubrication

Question 20

what makes up the outer layer of the eyeball

Answer 20

the sclera and cornea

Question 21

what covers the sclera

Answer 21

conjunctiva

Question 22

true or false: the conjunctiva covers the cornea

Answer 22

false

Question 23

what is subconjunctival haemorrhage

Answer 23

where a blood vessel in the conjunctiva suddenly bursts

Question 24

what makes up the middle layer of the eye

Answer 24

choroid, ciliary body and the iris

Question 25

what innervates the ciliary body

Answer 25

parasympathetics of the oculomotor nerve

Question 26

what happens when the ciliary body contracts

Answer 26

the 2 ciliary bodies come closer together (giving less pressure on the suspensory ligaments), this makes the lens fatter so light is refracted more

Question 27

where is aqueous humour produced

Answer 27

by the ciliary bodies

Question 28

how is aqueous humour circulated

Answer 28

once produced by the ciliary bodies it flows into the posterior and anterior chambers it then drains through the iridocorneal angle to drain the canal of Schlemm and into the venous system

Question 29

what is the inner layer of the eye

Answer 29

the retina

Question 30

what is the arterial supply to the retina

Answer 30

ophthalmic branch of the internal carotid artery

Question 31

where do the ophthalmic veins drain to

Answer 31

cavernous sinus

Question 32

what nerve supplies sensation to the eye

Answer 32

(ophthalmic) trigeminal

Question 33

what nerve supplies motor to the eye

Answer 33

occulomotor, trochlea, abducens

Question 34

what nerve allows sensation to the eye

Answer 34

optic

Question 35

what us glaucoma

Answer 35

when the drainage of the aqueous humour is blocked causing an increase in intra-ocular pressure, damaging the optic nerve

Question 36

when looking at far objects, what causes light to refract the most

Answer 36

the Cornea

Question 37

describe the refraction of light when looking at close objects

Answer 37

the Cornea can't refract light enough so the ciliary bodies contract to fatten the lens, allowing more refraction

Question 38

what is the accommodation reflex

Answer 38

what occurs when looking at closer objects: - pupils constrict - eyes converge - ciliary muscles contract

Question 39

why do the eyes converge when looking at closer objects

Answer 39

to prevent too much light from entering

Question 40

what is presbyopia

Answer 40

when the lens becomes stiffer so unable to refract light as well when looking at closer objects

Question 41

what is cataracts

Answer 41

when the lens and cornea are no longer transparent so light isn't let through

Question 42

what is the purpose of the aqueous humour

Answer 42

supply nutrients and oxygen to the lens and cornea as these are avascular in order to remain translucent

Question 43

what are the intrinsic muscles of the eye

Answer 43

- muscles of the iris (sphincter/dilator papillae) | - ciliary muscle

Question 44

what are the 6 extra-ocular muscles controlling eye movement

Answer 44

inferior rectus, superior rectus, medial rectus, lateral rectus, superior oblique and inferior oblique

Question 45

which of the extra-occular muscles are supplied by the trochlea nerve

Answer 45

superior oblique

Question 46

which of the extra-occular muscles are supplied by abducens

Answer 46

lateral rectus

Question 47

what are the functions of the extra ocular muscles

Answer 47

- medial/lateral rectus = allows medial/lateral movement - inferior rectus = down and in - superior rectus = up and in - inferior oblique = up and out - superior oblique = down and out

Question 48

how do you test the superior oblique muscle

Answer 48

move eye medially and then down

Question 49

how do you test the inferior oblique muscle

Answer 49

move eye medially and then down

Question 50

how do you test the inferior rectus

Answer 50

move eye laterally and down

Question 51

how do you test the superior rectus

Answer 51

move eye laterally and up

Question 52

what will you see in occulomotor damage

Answer 52

pupil dilation ptosis eyes will go down and out

Question 53

what will you see in trochlea damage

Answer 53

up and in

Question 54

what will you see in abducens damage

Answer 54

eye will be pulled medially

Question 55

what is uveitis

Answer 55

inflammation of the choroid layer in the eye