Head & Neck Surgery: Eyes (Exam II) Flashcards
Eye Anatomy placeholder
What produces the aqueous humor?
Ciliary body
What artery perfuses the majority of the orbital structures?
Where does this artery branch off from?
Opthalmic artery (branches off the internal carotid).
Where does the opthalmic vein drain?
Cavernous sinus
Which CN transmits neural signals from the retina?
Optic Nerve (CN II)
Which cranial nerves control extraocular muscle movement?
- III (Oculomotor)
- IV (Trochlear)
- VI (Abducens)
Which CN transmits pain and touch sensations of the eye?
Trigeminal (V)
Which CN innervates the orbicularis muscle via its zygomatic branch?
VII (Facial)
Blockade of the facial nerve would prevent what?
Accurate TOF assessment of the orbicularis oculi
What provides sensation to the upper and lower eyelids?
- Upper - frontal branch of ophthalmic nerve
- Lower - maxillary nerve
What is normal intraocular pressure?
10 - 20 mmHg
> ____ mmHg is a pathological intraocular pressure.
> 25 mmHg
Quantity of _____ fluid and ______ blood volume help regular IOP.
aqueous fluid : choroidal blood volume
Which two anesthesia “things” have the greatest effect on IOP?
- Laryngoscopy
- Emergence
Coughing, straining, and vomiting can result in a _______ mmHg increase in IOP.
30 - 40 mmHg
How will CO₂ affect IOP?
Hypercapnia = ↑IOP via choroidal congestion
Hypoxia and hypertension will ↓IOP. T/F?
True
What common anesthetic drugs are known intraocular pressure increasing drugs?
- Succinylcholine
- Neostigmine
- Atropine
How much does IOP increase with sugammadex?
Trick question. Sugammadex does not increase IOP.
Ocular blocks will increase IOP by 5 - 10 mmHg. Which block will cause the greatest increase?
Peribulbar blocks
A forceful squeeze of our eyelids can increase IOP by _____ mmHg.
> 70 mmHg!
Normal blink is 10 mmHg.
What common anesthetic drugs decrease IOP?
- VAA
- IV anesthetics
- Short-acting opioids
- Mannitol
Depression of CNS ocular centers = relaxation of extraocular tone.
What effect do midazolam, nitrous oxide, and non-depolarizing neuromuscular blockers have on IOP?
No change
What is another name for the oculocardiac reflex?
Trigeminovagal Reflex
What are the triggers for the oculocardiac reflex?
- Traction on the extraocular muscles. Especially the medial rectus.
- Pressure on the globe
- Retrobulbar block
What surgery is the oculocardiac reflex seen in most frequently?
Strabismus repair of pediatric patients.
What are non-pharmacologic treatments of the oculocardiac reflex?
- STOP surgery
- Correct hypercapnia and/or hypoxia
- Prevention/pretreatment
What are the pharmacologic treatments for oculocardiac reflex?
- Atropine 7-10 mcg/kg IV
- Glycopyrrolate 0.2 mg IV
- LA in the rectus muscle