Anesthetics And Methods Of Drop Delivery Flashcards
What is the reason we use topical ocular anesthetic
Used to prevent eye pain during several procedures
Use topical ocular aesthetics to prevent eye pain during:
- diagnostics testing and procedures
- applanation tonometry
- gonioscopy
- ophthalmic examinations
- removal of foreign bodies or sutures
- surgery
What are some commonly used anesthetics used?
- cocaine
- tetracaine
- benoxinate
- proparacaine
Mechanism of action of topical anesthetics
- blocks nerve conduction to superficial cornea and conjunctiva by disabling the ability of the nerve cells to generate an action potential
- suppresses corneal and conjunctival sensitivity
Efficacy of topical anesthetic
-determined by their ability to suppress corneal sensitivity
Combining two ore more topical anesthetics
Does not produce an additive effect, but does increase the risk of slide effects
Side effects of topical ocular anesthetics
Severe local reaction are rare, systemic reaction are even more uncommon
Ocular toxicity of topical of anesthetic
- mild stinging and burning
- desquamation of corneal epithelium
- retards epithelial healing
What the most common side effect
Mild stinging and burning
What can increase the risk of adverse effects of topical anesthetic
Self medication
System toxicity of ocular anesthetic
Overdose from topical administration theoretically possible
Local hypersensitivity reactions to anesthetics
- Allergy can develop due to repeat exposure (glaucoma patients)
- mild transient blepharoconjunctivitis occurring 5-10 minutes following instillation
- little cross reactivity among topical anesthetics
Cross reactivtiy among topical anesthetics
Little cross reactivity
Usually only sensitive to one drug
Systemic hypersensitivity reactions to local anesthetics
No lifer threatening reactions reported
Self administration of topical anesthetic
- risk of adverse effects due to corneal toxicity
- vision loss secondary to permanent scarring
Hypersensitivity to topical anesthetics
Substitute different agent; little cross-sensitivity
Topical anesthetic and cultures
- they are toxic to micro organisms plus proparacaine least toxic
- will making getting a culture of bacterial infection difficult
Dry eye testing and topical anesthetics
-epithelial toxicity can confuse clinical picture
Pachymetry and topical anesthetics
Transient corneal swelling following anesthetic use
Perforating injuries and topical anesthetics
Endothelial toxicity
what is the concentration of proparacaine?
0.5% soln
How should proparacaine be stored?
In a tightly capped, opaque, and (ideally) refrigerated container to retard degradation
What should you do if proparacaine shows more than a faint yellow color?
It should not be used
Systemic toxicity of proparacaine
Extremely low
Penetration of proparacaine
Poor penetration of the conjunctiva and cornea
-quick to work, quick to wear off
Which is the least bacteriocidal of the topical anesthetics?
Proparacaine
Order of topical anesthetics in corneal toxicity from high to low
Tetracaine
Proparacaine
Benoxinate
Which topical anesthetic is least uncomfortable?
Proparacaine
Use prior to routine office procedures
Duration of action of proparacaine
Onset 10-20s
Duration 10-20 min
Contraindications and precautions of proparacaine
- corneal thickness instability lasting 5 minutes
- pregnancy category C (not completely safe to use if pregnant
Side affects of proparacaine
Allergy (rare)
Goal of eye drop instillation
To deliver a full dose of the drug to the eye while minimizing systemic exposure and maximizing patient safety and comfort
What is the preferred method for routine eye drop instillation?
Inferior fornix delivery
Why is inferior fornix delivery the preferred method for routine eye drop instillation?
- maximizes ocular contact time of drug
- minimizes drug loss
- increases ocular absorption
- and decreases systemic absorption
Steps for inferior fornix delivery
- tilt head back
- tell pt to look up
- pull lower lid away from globe
- check expiration date, shake and remove cap
- instill gt in lower eyelid (hold about 1” above the pocket)
- AVOID CONTAMINATION OF TIP
- place drop on conjunctiva, not cornea
- close eyes gently for 3 min
- apply pressure to puncta
Purpose of punctual occlusion after eye drops
- minimize drainage of medication into nasolacrimal apparatus, thereby maximizing ocular contact
- decrease systemic absorption of drug through nasal mucosa, minimizing risk of systemic adverse effects
Method of punctual occlusion after eye drops
Following eye drop instillation, instruct patient to close his eyes and apply gentle pressure to the medial canthal region for about 3 minutes
Recording eye drop instillation
-record name of the pharmaceutical agents used, including its cxn, how many drops used in each eye, and time of day
1 gt of 0.5% proparacaine OD and OS @ 11.35 AM
Alternatives to the instillation of eye drops
- medial canthus delivery
- spray bottle
- pledgets
Medial canthus delivery of eye drops
A lower anxiety technique for persons unable to cooperate with inferior fornix delivery
Technique for medial canthus delivery
- Head inclined back
- eyes closed
- eye drops placed on top of medial canthus
- patient instructed to blink repetitively
Spray bottle technique
- mist applied to closed lids with spray bottle and the patient be instructed to blink
- excess solution should be wiped off
- a second spray might be necessary, especially if the eyes were closed too tightly
Advantages of spray bottle
- efficacy reported to be equivalent as ophthalmic drops and more tolerable
- patients were more compliant and experienced less burning when the spray was used than when the ophthalmic drops were used
Disadvantages to spray bottle
- inability to deliver precise dosage
- lack of an established dose-response relationship for this type of administration
- potential for drug contamination
- most ophthalmic medications are not currently formulated for this type of application
Pledgets
- cotton swab saturated with drug solution then placed in the eye
- permits very long or very short contact time
- useful of inferior sector dilation, breaking synechia
