Mydriasis and Cyclopegias Flashcards
What are the main two enzymes responsible for sympathetic metabolism?
COMT and MAO
What is substrate for sympathetic neurotransmitters?
Tyrosine
What are the steps in Sympathetic nerve activity?
- Tyrosine converted to Dopa (also catecholamoine)
- Dopa- to dopamine (lipid membrane vessels)
- Dopamine converted NE
- NE increases causes an action potential causes calcium to come into nerve terminal
- High Ca. vesciles fuse open up to exterior and releases
- COMT can metabolize NE
- Stimulation of alpha 2 stops degranulation
NE remains will be reabsorbed by nerve. MAO will determine fate
What blocks reuptake of NE?
Cocaine (works indirectly and amplifies neuros)
What receptor inhibits sympathetic system ?
alpha 2
What is a precursor for tyrosine and melanin?
phenylalanine (too much can change simp pathway)
What causes lid retraction
Muellar’s (sympathetic)
What drug can be responsible for ptosis?
drug that stimulates Muellar’s (eye that seems to have ptosis doesn’t really have a ptosis its due to retracted eye lid)
Dilating in specific area?
sectoral dilation (keyhole pinhole)
Large angles found in?
myopes and aphakes
Reduced Sensitivity?
Age Related Miosis (older= smaller pupils
Unstable Diabetics
Post op pupils (drugs affect ANS)
Posterior Synechiae (iris stuck to lens)
Dark Irides
Pseudoexfoliation syndrome (iris looses muscle tone)
Increased Sensitivity
Down Syndrome (respond aggressively)
Poor Dilation Candidates?
Homocyternia and Marfan Syndrome
Pregnancy (use tropicamide)
Pigmentive glaucoma
Contraindications for dilating patients?
Lens/ Angles
Angle Closure can occur 4-8 hours after dilating drops
Sympothoaminmetic Amines?
Phenylepinephrine
Hydroxyamphetamine
Drugs used for red eye relief/ Decongestants that stimulate a and b receptors
Oxymetazoline
Naphazoline (Clear eyes)
Tetrahydrozoline (Visine)
Can cause Ptosis and Anisicoria
Phenylephrine
alpha 1: mydirasis
indiectinly cause NE to be released into cleft
How long does it take phenyleph. to produce mydriasis?
45- 60 min. This is the reason it is never used alone.
Common Indications of phenylephrine?
mydirasis 45-60 conuncitivl blnching mild accommodation suppression 2D Lid retraction IOP reduction
synergist of phenyllynine?
MAOis
TCADs
Atropine
antagonists of phenyeph.
methyldopa
Beta
Effects of phenyl?
rebound miosis and congestion bur photophobia anterior chamber pigment liberation hypertension: bradychar
Contraindications of phenyl
aneurisym, DM 1, CVD, MI, ateriosclerois, idio orthro hypotension
What doesn’t suppress accommodation ?
Hydroxyamphetamine
