Ophthalmology basics

Question 1

Drug causes of eye pathology:

Answer 1

Steroids can cause cataract/affect glaucoma

Anticholinergics can cause blurred vision and angle closure glaucoma

Question 2

Normal vision?

Answer 2

Snellen: 6/6 (UK)
20/20 (US)
Near: N6

Question 3

Protanopes…

Answer 3

Lack red-sensitive cones

Question 4

Deateranopes…

Answer 4

Lack green-sensitive cones

Question 5

Tritanopes…

Answer 5

Lack blue-sensitive cones

Question 6

Normal visual field?

Answer 6

60 degrees above and 75 degrees below fixation in each eye
Central visual field is 30 degrees from fixation
Blind spot is 15 degrees temporal to fixation
Nasal side 60 degrees to fixation
Temporal side 90 degrees to fixation

Question 7

What does a lesion at the optic chasm cause?

Answer 7

Bilateral hemianopia

Question 8

Lateral rectus action =

Answer 8

Abduction

Question 9

Medial rectus action =

Answer 9

Adduction

Question 10

Superior rectus action =

Answer 10

Elevation

Question 11

Inferior rectus action =

Answer 11

Depression

Question 12

Superior oblique action =

Answer 12

Intorsion

Question 13

Inferior oblique action =

Answer 13

Extorsion

Question 14

Outcome of CN III palsy?

Answer 14

Can abduct, elevate and slightly depress the eye

No other movements

Question 15

What does the superior division of the oculomotor nerve (CN III) supply?

Answer 15

Superior rectus

Levator palpeerde superioris (elevates upper eyelid)

Question 16

What does the inferior division of the oculomotor nerve (CN III) supply?

Answer 16

Medial rectus
Inferior rectus
Inferior oblique
Parasympathetic efferent to constrictor pupillae and the ciliary muscles for accommodation

Question 17

Which cranial nerve innervates superior oblique?

Answer 17

CN IV - Trochlear

Question 18

CN IV - Trochlear nerve innervation:

Answer 18

Superior oblique: actions = intorsion, depression and abduction

Question 19

How does CN IV trochlear nerve palsy present?

Answer 19

Vertical or diagonal double vision
Deviation more obvious when head tilted to the side as superior oblique is a depressor and when the head is tilted it cannot depress

Question 20

What cranial nerve innervates lateral rectus?

Answer 20

CN VI - Abducens

Question 21

CN VI - Abducens innervation:

Answer 21

Lateral rectus: actions = abduction

Question 22

Features of congenital esotropia/squint:

Answer 22

Affected eye unable to fixate and is inward looking
Cover unaffected and affected eye will fixate
Uncover unaffected eye and it will compensate by moving in

Question 23

Difference between esotropia and exotropia?

Answer 23

Esotropia is inward looking whereas exotropia is outward looking

Question 24

What can cause an abnormal red reflex?

Answer 24

Cataracts
Lens opacity
Media opacity

Question 25

What does a child with a white reflex indicate?

Answer 25

Retinoblastoma

White reflex = leukochorea

Question 26

Treatment for sub-conjunctival haemorrhage (above sclera)?

Answer 26

Topical lubricants

Question 27

Treatment for bacterial conjunctivitis with discharge?

Answer 27

Topical abx

Chloremphenicol

Question 28

What is conjunctival chemosis and how do you treat it?

Answer 28

Fluid under the conjunctiva associate with conjunctivitis

Topical abx

Question 29

What can herpes simplex keratitis lead to?

Answer 29

Dendritic ulcer

Question 30

Treatment for herpes simplex keratitis?

Answer 30

Topical antiviral ointments

Avoid steroids unless prescribed by an ophthalmologist

Question 31

What can dry ocular surface lead to?

Answer 31

Punctate erosions

Question 32

What can a contact lens problem lead to?

Answer 32

Corneal ulcer and hypopyon (pool of pus at base of cornea)

Eye emergency

Question 33

Treatment for corneal ulcer?

Answer 33

Topical abx

Urgent ophthalmology referral

Question 34

What is hypopyon?

Answer 34

A pool of pus at the base of the cornea

Question 35

What can a mid-dilated pupil and hazy cornea lead to?

Answer 35

Acute glaucoma causing ischaemia of the iris and dilation of the pupil
Refer to an ophthalmologist

Question 36

What is papilloedema?

Answer 36

Bilateral optic disc swelling with normal visual acuity

Question 37

Haemorrhage of the optic disc is a classic feature of which condition?

Answer 37

Glaucoma