opthal

Question 1

What is normal IOP

Determinants of IOP

Answer 1

• 10-20mmHg
  1. aqueous humor most important: obstruction to flow from closed or open angle glacoma. mydriasis can impede flow (phenylephrine, epi, BB echiophate)
  2. increase in Blood volume from increase CVP or arterial BP
  3. mass effect/external compression
  4. Anetshestics: decrease via lowering CVP, EOM tone, and resistance to aqueous humor drainage (by causing miosis). succ may cause transient increase,
  5. hypercarbia hypoxia acidosis can increase ICP (increase choroidal dilation-layer in posterior globe containing blood vessels and capillaries

Question 2

Drugs used to treat glacoma

Answer 2

1. first line-topical cholinergics (echothiolate-acteylcholinesterase inhibitor-prolong succ miva, and ester locals), BB, adrenergics
2. carbonic anhydrase inhibitors
3. surgery
4. acute think of mannitol

Question 3

Response to OCR

Answer 3

1. tell surgeon to stop
2. if severe tx w atropine/CPR 20mcg/kg
3. correct any hypoxia or hypercabia that worsens reflex
4. . persisted cconsider infiltration of EOM w local
5. self limited and self extinguishes

Question 4

Issues w suc in opthamology

Answer 4

1. interfere w forced duction test used to access EOM imbalence
2. may predispose to MH?
3. may make IOP pressure testing inaccurate

Question 5

implications of strabismus

Answer 5

1. NMD MH risk- no longer considered an issue
2. OCR
3. succ & forced duction test
4. N/V common

Question 6

etiology post post op blindess

RF for AION, tx?

Answer 6

ION-anterior posterior (decreased oxygen delivery to optic nerve): painless, decreased pupiillary response to light, visual field defect, lack light perception, + optic disc edema in anterior (normal disc in posterior)

central retinal artery/vein occulision: CRAO: cherry red macula, imapird light reflex, branch: either normal or mpaired light reflex

acute glacoma; severe periobital pain, pale and dry eye, dilated pupil

hemorragic retinopathy: floaters, pre-retinal hemorrhages, retinal edema

cortical blindness: inabillity to follow moving objects w head stationary, absent response to visual threat,

glycine toxicity: dilated nonreactive pupil,

corneal abrasiaon: foregn body sensation, conjutiviits, photophobia, tearing

RF: atherosclosis, age, HTN smoking DM, vascular dz, increased IOP

hypotension, anemia, vasoconstrictors

Question 7

timing for intravitreal injection of air sulfur hexafluoride ) or perfluoropropane (C3F8) and nitrous

Answer 7

air 5 days

sulfur hexaflurodide 10 days

perfluropropane 30 days

Question 8

what to do when POVL occurs

Answer 8

-impaired oxygen delivery: correct hypotension, aanemai electrolytes

elevated head of bed to failitate venous drainage

urgent optha consult

Question 9

RF for PION

how to reduce risk

Answer 9

prolonged procedures >6.5 hrs & susstancial blood loss 45% of EBV have strongest association -consider staging procedures

type and amount of fluid admin

prone

avoid hypoxia, hypotension anemia,

keep head above heart to promote venous drainage

avoid excessive pressure on eyes

staging procedure-if long and complications