Orbit, Eyes, and Lacrimal System

Question 1

Orbit floor

Answer 1

PaM-Z: palatine, maxillary, zygomatic

• Clinically WEAKEST
• hypoethesia due to infraoribtal nerve trauma

Question 2

Medial wall of orbit

Answer 2

-SMEL
sphenoid (lesser wing), maxillary, ethmoid, lacrimal
-thinnest
-lacrimal sac fossa
-optic foramen
-inferior oblique muscle arising from lacrimal crest

Question 3

Orbital roof:

Answer 3

frontal, lesser wing of sphenoid

Question 4

Lateral wall

Answer 4

Great-Z: greater wing of sphenoid, zygomatic

-THICKEST wall

Question 5

Extraocular muscles

Answer 5

4 rectus muscles, 2 oblique muscles

inferior oblique is the only one that doesn’t arise from back portion of the globe

Question 6

Neurovasculature

Answer 6

cranial nerves (oculomotor does most; lateral rectus from abducents, superior oblique from trochlear)
optic nerve, ophthalmic artery and vein

Question 7

Sensory innervation

Answer 7

CN V (trigeminal)
Ophthalmic division (V1): nasociliary, frontal (supraorbital, supratrochlear), lacrimal nerves

Maxially division (V2): infraorbital (cheek numbness w/ damage), zygomatic

Question 8

Oculocardiac reflex

Answer 8

Increased pressure on eye, pulling on eye muscles–>bradycardia, asystole, arrhythmia

afferent: CN V1 (ciliary ganglion to trigeminal)
efferent: CN X

Treatment:

• release globe/muscle
• atropine
• glycopyrrolate
• preventative (or provoking): retrobulbar/peribulbar block

Question 9

Orbital fractures

Answer 9

-floor and medial wall most commonly affected -Most often occurs medial to infraorbital canal–>leads to hypesthesia in cheek and upper lip (V2)

Repair in w/in 2-4 weeks if:

• enophthalmos (eye sunken in because of volume in orbit decreased)
• incarcerated muscle/orbital tissue
• > 50% of wall fractured

Question 10

Orbital cellulitis

Answer 10

• presents with pain, erythematous lid swelling, TTP
• EOM restriction, proptosis
• Later: vision loss, RAPD, decreased color vision, increased IOP
• Mgmt: broad spectrum antibiotics, CT orbits with contrast, abscess I/D

Question 11

Layers of eyelid below lid crease

Answer 11

Skin
orbicularis muscle
tarsus (Meibomian glands inside)
conjunctiva

Question 12

Layers of upper eyelid above crease

Answer 12

skin
orbicularis muscle
septum
fat
levator aponeurosis
Muller's muscle 
conjunctiva

Question 13

cavernous sinus thrombosis

Answer 13

• sequelae of uncontrolled orbital cellulitis/facial cellulitis
• Orbital veins are valveless: retrograde spread of infections to cavernous sinus
• CN III, IV, V1, V2, VI palsies, proptosis, chemosis, altered mental status
• may have permanent neuropathies; death from sepsis

Question 14

Layers of lower eyelid below crease

Answer 14

skin
orbicularis
septum
fat
LL retractors (CPF)
Muller's muscle
conjunctiva

Question 15

Arterial supply

Answer 15

superior/inferior marginal arcades (2mm from margin)

Superior peripheral arcade (between levator and Muller’s)

Question 16

Preseptal cellulitis

Answer 16

• In front of septum
• Can open/move eye
• No involvement of orbit
• Oral Abx, drain pus

Question 17

Chalazion

Answer 17

• plugged Meibomian glands within tarsus cause inspissation of meibum (oil)
• treatment: warm compress

Question 18

Eyelid trauma

Answer 18

if fat protruding through, septum has been violated

-Posterior to that is levator aponeurosis, if damaged could lead to ptosis

Question 19

avulsion

Answer 19

-torn eyelid, need to repair levator

Question 20

Principles of eyelid repair

Answer 20

• anterior vs posterior lamella
• fat visible: check levator
• eyelid margin involvement
• Canalicular involvement (tear drainage system)

Question 21

Repair algorithm for eye damage

Answer 21

Reconnect levator aponeurosis to tarsus
-reappose tarsus
-reappose eyelid margins
reappose skin and orbicularis

Question 22

Where is lacrimal sac?

Answer 22

below median canthal tendon

Question 23

tear production

Answer 23

lacrimal and accessory glands

Lacrimal gland:
two lobes
ducts from both lobes pass thru palpebral lobe to enter conjunctiva
-symp, parasymp, sensory nerves innervate orbital lobe
-bg to func at 6 weeks

Accessory glands:
-Krause
-Moll
-Zeis
?wolfring, meibomian?

No lacrimal gland? dry eye but accessory glands help with tearing.

Question 24

tear drainage

Answer 24

lacrimal punta, canaliculi, lacrimal sac, duct

Question 25

Dacryocystitis

Answer 25

Infection of lacrimal sac due to nasolacrimal duct obstruction

• treat w/ abx
• when infection resolved, treat with surgical bypass (dacryocystorhinostomy)

Question 26

Adenoid Cystic carcinoma

Answer 26

• MC malignant LG tumor
• perinueral invasion (pain), bone destruction, rapid spread (months)
• death from intracranial extension/mets (80% mort at ten years)
• Treatment: rad, chemo, exenteration, targeted chemo with exent/XRT

Also take out orbit with lacrimal gland so can’t spread.