Oc pham: ocular anesthetics

cornea is innervated by what nerve

nasociliary branch of ophthalmic nerve

ability to sense pain

algesia

ability to perceive sensation

esthesia

movement

kinesia

list 3 parts of anesthetic chemical structure

amine = hydrophilic

aromatic = hydrophobic

intermed chain = potency/tox

Aromatic and Amine groups help with absorption

Ester anesthetics :

what metabolizes them, longer/shorter duration vs amide?

Benoxinate

tetracaine

proparacaine

plasma cholinesterase

shorter duration

amide anesthetics :

what metabolizes them, longer/shorter duration vs amide?

lidocaine

liver

longer

ester/amide which more likely allergic

ester --> karaan allergic proparacaine

pH anesthetics, how do tears impact penetration?

weak base

Instillation into the tears (ocular surface)

• Tears are neutral to slightly basic pH which increases non-ionized form

of the molecule

• Enhancing ability to penetrate the nerve cell membrane

• pH of instillation site may increase/decrease effects of

anesthetic

Anesthetics- Mechanism of Action

Na+ channel blocker

• Prevents Na+ from entering the nerve cell

• Prevents depolarization- no action potential formation

• No generation of nerve impulse

anesthesia • Onset: ___ after instillation

15-20 seconds

anesthetic Prolonged duration when paired with ____

epinephrine --> vessel constriction so slow breakdown.

anesthetics are pre cat ___

C --> no human studies may be risk

• Most used topical anesthetic

0.5% Proparacaine HCl solution

duration of 0.5%, 1% tetracaine, 0.5% proparacaine, 0.25% benoxinate/fluoroscein, lidocaine

Tetracaine HCl 0.5%

Duration: 20 min

Tetracaine HCl 1.0%

Duration: 1 hour

Proparacaine HCl 0.5%

Duration: 15 min

Proparacaine HCl 0.5%/Sodium Fluorescein 0.25% - 15 minutes

lidocaine

30-60 min

May be good option for tonometry on contact lens wearers

0.35% Disodium Fluorexon/0.4% Benoxinate HCl solution

vs normally use 0.25% sodium fluoroscein/0.4% benoxinate HCL

Only amide topical anesthetic available

0.35% Lidocaine HCl solution

longest duration topical anesthetic

1.0% tetracaine --> 1 hr (cataract surgery_

ADR ocular anesthetics (esters)

Desquamation of corneal epithelial cells

• Occurs within minutes after topical instillation

• Can reduce visual acuity

• Results in corneal staining

• Conjunctival injection/hyperemia

• Lacrimation

• Photophobia

• Induce dry eye signs/alter dry eye

measurements

Limit drop use:

• Tetracaine: 7 drops

• Proparacaine: 14 drops

treatment for blepharoconjunctivitis, potential cause?

topical steroid --> note allergy to ester anesthetics in chart

_____ is added to anesthetic to prolong anesthetic

action and promote hemostasis

epinephrine

local anesthesia contraindicated in what conditions?

• Angle closure glaucoma

• Brain injury

• Coronary insufficiency

• Peripheral vascular disease

• Labor and delivery

DO NOT USE EPINEPHRINE IN:

contaminated wounds

MAO inhibitors

peripheral vascular disease

disorders that Epinephrine should be used with caution

• Stable Diabetics

• Hypertension

• Ateriosclerosis

• Thyrotoxicosis

• Heart Block

• Cerebrovascular disease

what local anesthetic can be used for contaminated wounds and vascular diseases,

lidocaine --> cause vasodilate not constrict like others w epinephrine

what local anesthetic can be used for cardivacular risk, cerebrovascular risk?

lidocaine --> cause vasodilate not constrict like others w epinephrine

what local anesthetic can be used for nerve block?

lidocaine --> cause vasodilate not constrict like others w epinephrine

what local anesthetic Useful in highly vascular areas like the eyelids

Lidocaine + Phenylephrine

Lidocaine + Phenylephrine duration

60-400 minutes