Anesthesia for opthalmic procedures

Question 1

Identify the anatomy of the frontal view of the orbit

Answer 1

1.Superior Rectus Muscle
2. Superior Oblique muscle
3. Trochlea
4. Medial Rectus muscle
5. Infereior Oblique muscle
6.Inferior Rectus Muscle
7.Lateral Rectus muscle

Question 2

Identify the anatomy of the lateral view of the orbit

Answer 2

1. Superior oblique muscle
2. Superior Rectus muscle
3. Levator palpebrae muscle
4. Medial and Lateral rectus muscle
5. Inferior rectus muscle
6. Inferior oblique muscle

Question 3

How is the oculocardiac reflex generated?

Answer 3

By pressure on the globe, the orbital structures(e.g., the optic nerve), or the conjunctiva, or by traction on the extraocular muscles(particularly the medial rectus muscle)

Question 4

The oculocardiac reflex most often results in

Answer 4

Acute sinus bradycardia.
However, it may also cause a wide variety of other cardiac dysrhythmias, such as nodal rhythms, atrioventricular block, ventricular ectopy, idioventricular rhythm, and asystole

Question 5

How arrythmiaas during ophtalmic procedures are managed?

Answer 5

1. Instruct the surgeon to immediately cease all pressure or traction on the orbit, while simultaneously assessing the patient for adequate oxygenation, ventilation and anesthetic depth because one of these can cause arrythmias

Question 6

What medication is administered in the presence of oculocardiac reflex?

Answer 6

For less severe bradycardia administer Glycopyrrolate

Atropine 2 to 3 mg may be required for complete vagal blockade. Administer atropine with caution as it may induce dysrhytmias.

The surgeon may proceed ONLY AFTER the dysrhytmia is resolved

Question 7

Glaucoma is caused by

Answer 7

Chronically elevated IOP that leads to retinal artery compression.

IOP is reduced by drugs that reduce aqueous humor production or facilitate aqueous humor drainage

Question 8

What drugs decrease the aqueous humor production?

Answer 8

Acetazolamide inhibits carbonic anhydrase and decreases aqueous humor production.

Timolol is a non-selective beta antagonist that decreases aqueous humor production.

Question 9

What drugs facilitate aqueous humor drainage?

Answer 9

Echothiophate is an irreversible cholinesterase inhibitor that promotes aqueous humor drainage via the canal of Schlemm.

It can prolong the duration of succinylcholine and ester-type local anesthetics

Question 10

Strabismus surgery

Answer 10

corrects the misalignment of the extraocular muscles and re-establishes the visual axis.

Question 11

Considerations for patients undergoing for strabismus surgery

Answer 11

Increased risk of PONV

Increased risk of activating the oculocardiac reflex(afferent CN 5 + efferent CN 10

Question 12

What is Sulfur hexafluoride (SF6)?

Answer 12

is a gas that is placed over the retina during retinal reattachment, vitrectomy, and macular hole repair

Ocular gas bubble placement

Question 13

__________ can expand the SF6 bubble, compromise retinal perfusion, and cause permanent blindness

Answer 13

Nitrous Oxide

Question 14

Discontinue N2O ____ minutes before the SF6 bubble is placed.

Avoid N20 for _______days after the SF6 bubble is placed.

Answer 14

Discontinue N2O 15 minutes before the SF6 bubble is placed.

Avoid N20 for 7-10 days after the SF6 bubble is placed.

Question 15

Alternatives to SF6 and times to avoid N20

Answer 15

Silicone oil = 0 days

Air bubble = 5 days

Perfluoropropane (C3F8) = 30 days

Question 16

________________ is the most common injury occurring after general anesthesia

Answer 16

Corneal abrasion is the most common injuryoccurring after general anesthesia

It is believed toresult from the drying of the exposed cornea orfrom direct trauma, such as an anesthesia-maskinjury. Ensuring that the eyelids are closed andsecured with tape should provide satisfactoryprotection of the cornea

Question 17

_______________ can result from spillage of cleaning materials or preparatory solutions into the eye. In these cases, the eye should be flushed immediately with saline

Answer 17

Chemical injury

Question 18

____________________ may result from prolonged pressure on the eye. This type of injurymay result with the patient in the prone position.

Answer 18

Central retinal artery occlusion may result from prolonged pressure on the eye. This type of injury may result in the patient being in a prone position.
Attention to padding and periodic checks of the eyes is necessary, especially for long procedures.

Question 19

Ophthalmic Anesthesia complications include

Answer 19

Retrobulbar Hemorrhage*
Intravascular Injection*
Globe Puncture*
Optic Nerve Sheath
Trauma*
Ocular Ischemia*
Extraocular Muscle Palsy and Ptosis*
Facial Nerve Blocks