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Neurology and Special Senses > Anatomy of the Orbit, Eyelids and Lacrimal System > Flashcards

Anatomy of the Orbit, Eyelids and Lacrimal System Flashcards

1
Q

What bones make up the orbit?

A 
Frontal
Sphenoid
Ethmoid
Maxilla
Zygomatic
Lacrimal
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2
Q

Which parts of the orbit are particularly susceptible to fracture?

A

Inferior and Medial parts

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3
Q

What is the function of the eyelid?

A

Protect cornea and eyeball from injury

Keep cornea moist by covering in tear film

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4
Q

What muscles move the eyelids and what innervates each muscle?

A

Orbicularis Oculi - facial nerve (VII)

Levator Palpabrae Superioris - oculomotor nerve (III)

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5
Q

What is a stye?

A

Infection of the glands of Zeiss, Moll or of the eyelash follicle

Commonly caused by staph aureus

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6
Q

What is a chalazion?

A

Painless swelling of the eyelid - caused by blockage of the tarsal gland

Also known as meibomian cyst

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7
Q

What makes up the lacrimal apparatus?

A

Lacrimal glands
Lacrimal ducts
Lacrimal canaliculi

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8
Q

How do tears flow through the lacrimal apparatus?

A

Gland produce components of tears and secrete onto eye through the lacrimal duct

Pass through lacrimal lake at medial angle of eye

Pass to nasal cavity through nasolacrimal duct

Swallowed

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9
Q

What happens if there is a blockage in the lacrimal apparatus?

A

No anastomosis so there is an overflow of tears - epiphora

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10
Q

Why are tears important?

A

Provide smooth surface for light rays to refract uniformly

Provide lubrication - prevent dry eyes

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11
Q

What can dry eyes cause?

A

Damage to epithelial surface of cornea and conjunctiva –> sensation of grittiness

Risk of infection

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12
Q

What should you consider if dry eyes are caused by reduced tear production?

A

Autoimmune causes - Sjogrens, RA

Medication - Anti-histamines

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13
Q

How can injury to the facial nerve lead to excess tear production?

A

Orbicularis oculi paralysis –> eyelid partially open and lose protective blinking –> cornea dry and unprotected from dust –> irritation of eyeball lead to excess tear formation

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14
Q

How may patients with a blowout fracture present?

A

Sunken orbits - pain
Reduced eye movement
Double vision
Loss of sensation to cheeks and upper gum - lose infraorbital nerve

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15
Q

What is seen on X-Ray in a blowout fracture?

A

Teardrop sign

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16
Q

What vasculature is important in ophthalmology?

A

Ophthalmic artery - from internal carotid
Central retinal artery - from ophthalmic artery - internal surface of retina
Ophthalmic vein - drain into cavernous sinus

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17
Q

What are the foramen in the orbit?

A

Optic canal - optic nerve and ophthalmic artery

Superior orbital tissue - CN III, IV, VI, ophthalmic branch of trigeminal, superior orbital vein

Inferior orbital fissure - inferior orbital vein

18
Q

What are the common causative organisms of conjunctivitis?

A

Adenovirus
Staph
Strep pneumoniae
H Influenzae

19
Q

How does bacterial conjunctivitis present?

A

Thick purulent discharge

Eyes stick together

20
Q

How does viral conjunctivitis present?

A

Serous discharge
Recent URTI
Periauricular lymph nodes

21
Q

If conjunctivitis persists for more than 7 days, what should be done?

A

Swab

22
Q

What are the general features of conjunctivitis?

A

Bilateral
Generalised red eye
Irritated gritty feeling
History of close contact

23
Q

How is viral conjunctivitis managed?

A

Self limiting within 2 weeks
Can use lubricant drops and warm water
Careful sharing towels

24
Q

How is bacterial conjunctivitis managed?

A

Antibiotics if severe

Delayed prescribing of Chloramphenicol (if not resolved after 3 days)

25
Q

How does conjunctivitis due to chlamydial infection present?

A 
Mild infection
Moderately thick discharge
Periauricular lymphadenopathy
Lid follicles
Sexual history
Poor response to Abx
26
Q

How does gonococcal conjunctivitis present?

A

Severe hyperactive hyperpurulent discharge
Rapid keratitis
Highly infection - require contact tracing

27
Q

What is allergic conjunctivitis?

A

Type 1 hypersensitivity reaction with mast cell degranulation and histamine release

Can be perennial, season or atopic

Common allergens to allergic rhinitis

28
Q

How does allergic conjunctivitis present?

A

Itchy watery red eye with lid oedema
Large papillae under eyelids
Degree of blepharitis

29
Q

How is allergic conjunctivitis managed?

A

Systemic and topical antihistamines
Cool eye baths
Topical mast cell stabilisers

30
Q

How are dry eyes managed?

A

Lid hygiene
Treat underlying cause
Drops, gels and ointments (at night as cause blurring)

Further management - steroids, punctual plugs, surgery

31
Q

What is ectropion?

A

Eversion of the lid margin leading to corneal and conjunctival exposure

32
Q

What causes ectropion?

A

Age related condition
Tumour push eyelid out
CN VII palsy

33
Q

How does ectropion present?

A

Irritated red eye

34
Q

How is ectropion managed?

A

Surgery

Lubricants can be useful while waiting for surgery

35
Q

What is an entropion?

A

Inversion of eyelid leading to corneal and conjunctival irritation

36
Q

What causes entropion?

A

Age related
Muscle spasm - ocular irritation
Trachoma

37
Q

How does entropion present?

A

FB sensation
Red
Irritated

38
Q

How is entropion managed?

A

Surgery only corrective option

Can tape eye while waiting

39
Q

What is trichiasis?

A

Eyelashes misdirected and in contact with ocular surface

40
Q

What causes trichiasis?

A

Following inflammation and scarring of eyelash follicle

41
Q

How is trichiasis managed?

A

Remove lashes with epilation or cryotherapy

Neurology and Special Senses (28 decks)

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