Quiz 4

Question 1

3 layers of sphere

Answer 1

• Sclera
• Uveal tract (middle layer)
• Retina

Question 2

look at slide 3

Answer 2

.

Question 3

Middle Layer (called what?) of eye has 3 structures?

Answer 3

• Choroid : Layer of blood vessels, located posteriorly
• Ciliary Body: behind iris, produces aqueous humor
• Iris: pigmented, controls light entry

Question 4

Traction of ______ on ______ causes detachment

Answer 4

vitreous

retina

Question 5

Scarring, bleeding or opacification of vitreous is treated with ________

Answer 5

vitrectomy

Question 6

look at slide 8

Answer 6

.

Question 7

All ocular muscles originate in the ____ apex around the _________, except for the __________.

Answer 7

orbital

annulus of Zinn

inferior oblique

Question 8

Ocular Cardiac Reflex (OCR) manifests as:

Seen especially with ___________________.

Answer 8

• Bradycardia
• AV block
• Ventricular ectopy
• Asystole (rarely)

medial rectus traction

Question 9

look at slide 11

Answer 9

.

Question 10

look at slide 13

Answer 10

.

Question 11

Blood supply to eye dependent on intraocular perfusion pressure: equation?

Answer 11

MAP - IOP

Question 12

The quantity of aqueous and blood volume regulates ____

Answer 12

IOP

Question 13

Normal IOP ______ mmHg

Answer 13

10-22

Question 14

production of aqueous humor is by?

Answer 14

carbonic anhydrase

Question 15

Venous pressure: Increase in CVP increase IOP, even more than increase in BP.
Coughing, straining, breathholding, and vomiting increases IOP by obstruction of drainage. IOP may increase up to 40x with coughing….

Answer 15

.

Question 16

Decreased PaCo2 results in a fast drop in IOP from choroidial vasoconstriction
Increased PaCO2 results in a slow increase in IOP
A fast respiratory rate may increase IOP from insufficient venous drainage…..

Answer 16

.

Question 17

Metabolic acidosis _______ the choroid vessel volume and therefore IOP
Metabolic alkalosis ________ the choroid volume and the IOP

Answer 17

decreases

increases

Question 18

look at slide 23

Answer 18

.

Question 19

Inhalation agents drop IOP by:

Answer 19

• lowering BP and thereby decreasing choroidal volume
• relax extraocular muscles and lower wall tension
• Pupil constriction enables aqueous outflow

Question 20

Med consideration for eyes:

Answer 20

• Ketamine may increase as it usually raises BP and doesn’t relax extraocular muscles
• Etomidate is associated with myoclonus (10-60%) and may not be appropriate with an open globe
• Succinylcholine (Sch) increases IOP

Question 21

Succinylcholine: Prolonged contracture alters forced duction test (test for extraocular muscle balance) for 20 minutes and may influence the type of strabismus surgery done….

Answer 21

.

Question 22

Carbonic anhydrase inhibitor: Acetazolamide (diamox) decreases aqueous production by inhibiting Na pump responsible for secretion of aqueous humor, decreasing IOP. IV dose 500mg, acts w/n minutes Chronic use depletes Na, K, and bicarb, leading to metabolic acidosis. Check lytes preop for chronic use patients….

Answer 22

.

Question 23

Osmotic diuretic: Mannitol used IV introp to drop IOP. Increases circulating blood volume (CHF) and pt may require urinary catheter. Max effect 30-45 minutes, returns to baseline 5-6 hours…

Answer 23

.

Question 24

topical anticholinesterase drug maintain miosis to Rx glaucoma.

Answer 24

Echothiophate

Risk: prolonged muscle paralysis after succs BC depletes plasma cholinesterases

Question 25

2 cholinergic drugs used to constrict pupil. Bradycardia and acute bronchospasm have been reported

Answer 25

Pilocarpine Acetylcholine

Question 26

Flomax (Tamsulosin hydrochloride) has selective alpha antagonistic properties. It binds the iris dilator muscles, affecting iris dilation and complicates cataract surgery. Iris remains floppy even after 7-28d off therapy...

Answer 26

.

Question 27

3 types facial nerve block

Answer 27

1) Van Lint 2) Atkinson 3) O’Brien

Question 28

Blocks entire trunk of facial nerve. Expect lower facial droop postop for several hours. Injection is close to vagus and glossopharyngeal nerve. Associated w/ vocal cord paralysis, laryngospasm, dysphasia and resp distress

Answer 28

Nadbath Rehman block

Question 29

Retrobulbar Block: Superior rectus muscle runs outside the muscle cone and may not be blocked as noted by intorsion on downward gaze....

Answer 29

.

Question 30

look at slide 47-50

Answer 30

.

Question 31

RBB contraindications

Answer 31

- Bleeding disorders (risk RB hemorrhage) - Extreme myopia (longer globe more at risk of perforation) - Open eye injury (pressure of fluid behind eye may force intraocular contents out through wound)

Question 32

look at slide 52-53

Answer 32

.

Question 33

N2O should be d/c’d 15 minutes before placement of sulfur hexaflouride and avoided for 7 to 10 days after....

Answer 33

.

Question 34

Another vitreal air agent, perfluoropropane (C3F6) persists for weeks. Avoid N2O for one month after instillation of this agent....

Answer 34

.

Question 35

which surgeries are air gas bubbles placed?

Answer 35

- Vitrectomy - retinal detachment - vitreoretinal surgeries

Question 36

scleral buckle surgery issues:

Answer 36

Painful and high risk n/v as well as nucleation surgeries, top 2