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
Open Angle Glaucoma is a ______ condition.
chronic
_____ _____ _____ causes chronic pressure elevation and development of open angle glaucoma.
Trabecular meshwork sclerosis
How painful is the development of open angle glaucoma?
Gradual and painless
What are the treatment goals of open angle glaucoma?
- ↓ IOP
- ↓ aqueous humor production
- Trabeculectomy/trabeculoplasty
Acute dilation of the iris with obstruction of aqueous drainage is…
Closed angle glaucoma
Very painful.
What is the treatment for closed angle glaucoma?
Iridotomy
How quickly must iridotomy be performed for closed angle glaucoma?
< 24 hours
_______ drugs MUST be avoided in closed angle glaucoma patients.
Anticholinergic Drugs
- Scopolamine
- Antihistamines
- Decongestants
- Antidepressants
- Benzodiazepines
- Ipatropium bromide
What carbonic anhydrase inhibitor is used for the treatment of chronic glaucoma?
Acetazolamide
What two common side effects are seen from acetazolamide?
- Hypokalemia
- PONV
What type of drug is Echothiophate?
What condition does it treat & how?
- Anticholinesterase inhibitor
- Treats glaucoma by maintaining miosis
Excess echothiophate can result in what?
- Systemic plasma cholinesterase inhibition
Caution with succinylcholine and ester LA’s
Phenylephrine using topically on the eye does what?
Dilates the eye
2.5% vs 10%
What drugs are used intraoperatively after lens extraction to induce pupillary constriction?
- Pilocarpine
- Acetylcholine
What is timolol used for?
Glaucoma via ↓ aqueous humor production
non-selective β1 blocker.
What possible side effects does timolol have?
- ↓ HR
- Bronchospasm
- CHF exacerbation
What type of drug is netarsudil?
Rho Kinase inhibitor
Treats glaucoma.
What is a cataract?
Opacity of the lens of the eye
What type of anesthesia is used for cataracts?
- Topical
- Regional
- Minimal/No IV anesthesia
What procedure is defined by the replacement of an infected/traumatized or poorly optical cornea?
Keratoplasty
How is a low and stable IOP maintained with a keratoplasty?
Mannitol (used because of lasting effects, 5-6 hours)
Is topical anesthesia an option for keratoplasty?
No.
- GETA typically
What are the advantages to regional anesthesia for keratoplasty’s?
- Perioperative analgesia
- Akinesia
- No oculocardiac reflex
- ↓ PONV
Succinylcholine
Echothiophate causes plasma cholinesterase inhibition.
What is a trabeculectomy performed for?
Refractory glaucoma
Excision of trabecula to increase drainage of aqueous humor & ↓IOP.
What two drugs are used in a trabeculectomy to prevent flap scarring and increase surgical success?
- Mitomycin-C
- 5-FU
What is surfer’s eye?
Ptyergium = triangular piece of fibrovascular tissue
________ is used to prevent recurrence after ptyergium excision.
Mitomycin-C
What is Ectropion?
What is Entropion?
Eyelid turning inward
What is blepharoplasty?
Correction of defect, deformity, or disfiguration of eyelids
What is ptosis?
Drooping upper eyelid
What is strabismus?
Misalignment of visual axis
- Double vision (Diplopia)
What conditions is strabismus associated with?
- Trisomy 21
- Cerebral Palsy
- Hydrocephalus
- Malignant Hyperthermia
- Myotonic Dystrophy
Describe the postoperative pain and nausea/vomiting after strabismus repair.
- No severe post-operative pain
- PONV is significant (50 - 80%)
What pain control strategies are used for strabismus repair?
- Ketorolac (minimize opioids)
What drug is added to local anesthetic injectate to prevent damage to the extraocular muscles?
hyaluronidase
What block provides akinesia of the CN II, III, and VI and a sensory block of the conjunctiva and cornea?
Retrobulbar block
What are possible complications of retrobulbar block?
- Hematoma
- Optic nerve injury
- Globe perforation
Which cranial nerves are blocked with a peribulbar block?
- CN III & CN VI
- CN II is not blocked.
What complication is avoided with a peribulbar block vs a retrobulbar block?
Retrobulbar hemorrhage
What topical anesthetic is used for eye surgeries?
0.5% proparacaine
What is blocked (and not blocked) with topical proparacaine?
Blocked:
- Conjunctive, cornea, and sclera
Not Blocked:
- Iris & ciliary body
