Eye Surgery - Quiz 4 Flashcards
What are the 3 Layers of the Eye?
Sclera - Outermost
Uveal Tract - middle
Retina - Innermost
Where does the most Focus Power of the eye come from?
Curvature of Cornea
What is the Uveal Tract made of?
Choroid
Ciliary Body
Iris
What is the Choroid?
Layer of Blood Vessels in the back of the Uveal Tract that supplies oxygen to the eye
Detachment = Vision Loss
What does the Ciliary Body do?
Sits behind Iris
Makes Aqueous Humor & Adjusts Focus by reducing tension on the Lens
What does the Retina contain?
Photoreceptors - neural signal
Pars Plana
NO Capillaries
Where is the Pars Plana of the Retina located?
Between Limbus of Cornea & End of Retina
(Area of Entry for Vitrectomies)
What is the Center of the Eye filled with?
Vitreous Gel
What does the Center of the Eye attach to?
Blood Vessels & Optic Nerve
What happens when there is Traction of the Vitreous on the Retina?
Detachment
What does the Superior Oblique muscle of the Eye do?
Rotates & Depresses Eye
What does the Inferior Oblique muscle of the Eye do?
Rotates Eye on Horizontal Axis
Extorts & Elevates Eyeball
Where do all Muscles of the Eye originate from with the exception of the Inferior Oblique?
Annulus of Zinn
What is the Ocular Cardiac Reflex (Five & Dime)?
Trigeminovagal Reflex that happens w/ Eye Manipulation (Especially Medial Rectus)
Bradycardia
AV Block
Ventricular Ectopy
Asystole
How does the Trigeminovagal Reflex work?
Afferent Impulses from Eyes –> Ciliary Ganglion –> Ophthalmic Trigeminal Nerve @ 4th Ventricle –> Trigeminal Sensory Nucleus –> Visceral Motor Neclei of Vagus –> Efferent Vagus –> Heart
With what type of Anesthesia does the Ocular Cardiac Reflex Occur?
Topical & General > Retrobulbar Blocks
What worsens the Ocular Cardiac Reflex?
Hypoxemia
&
Hypercarbia
How is Ocular Cardiac Reflex treated?
Stop Manipulation
Lidocaine Localization
Deepen Anesthetic
Atropine
Robinul
How is Intraocular Perfusion Pressure calculated?
MAP - IOP
What is the Normal IntraOcular Pressure?
10 - 22 mmHg
(> 25 mmHg is BAD)
The Globe is ________ with a _____ volume
The Globe is NON-COMPLIANT with a FIXED volume
What regulates IntraOcular Pressure?
Amount of Aqueous & Blood Volume
Production of Aqueous Humor is constant and is faciliated by _______
Production of Aqueous Humor is constant and is faciliated by CARBONIC ANHYDRASE
What can Increased IOP lead to?
Optic Disc Atrophy
Nerve Atrophy
Optic Artery Occlusion
What can Decreased IOP lead to?
Fluid Accumulation in the Eye
What happens to IOP with a Sudden BP Decrease of < 90 mmHg?
↓IOP
Los of Autoregulation
How does a Sudden BP Increase affect IOP
↑IOP, but normalizes d/t Drainage System
An Increase in CVP has a ______ effect than an Increase in BP regarding IntraOcular Pressure
An Increase in CVP has a GREATER effect than an Increase in BP regarding IntraOcular Pressure
How much can coughing increase IOP?
40x d/t Drainage Obstruction
How does Decreased PaCO2 affect IOP?
FAST drop in IOP d/t Choroidal Vasoconstriction
How does Increased PaCO2 affect IOP?
SLOW increase in IOP
How does Fast Breathing affect IOP?
INCREASE IOP d/t Insufficient Venous Drainage
How does Metabolic Acidosis / Alkalosis affect IOP?
Alkalosis = ↑Choroid Volume & IOP
Acidosis = ↓Choroid Volume & IOP
Blinking, Squinting, and Forced Lid Squeeze can increase IOP by _____, _____, and _____ respectively
Blinking, Squinting, and Forced Lid Squeeze can increase IOP by 5 mmHg, 25 mmHg, and 50 mmHg respectively
Which muscle relaxant increases IOP?
Succinylcholine
Which IV drugs can be given to Decrease IOP?
Acetazolamide - Carbonic Anyhydrase Inhibitor - Depletes Lytes
&
Mannitol - Osmotic Diuretic - Lasts 30-45 min, returning to baseline 5-6 hrs.
What is Echothiophate?
Topical Anti-Cholinesterase used to maintain Miosis & treat Gluacoma
What can happen if Echothiophate is systemically absorbed?
Total Cholinesterase Inhibition & Prolonged Post-Sux Paralysis
What drug is used to Dilate the Pupil?
Phenylephrine
What drugs are used to Constrict the Pupil?
Pilocarpine & Acetylcholine
May cause Bradycardia & Brochospasm
What is Timolol used for?
Beta Blocker used to treat Glaucoma
What can occur if Timolol is Systemically Absorbed?
Bradycardia
Bronchospasm
CHF
How does Flomax affect Cataract Surgery?
Binds Iris Dilator Muscles
&
Makes Iris Floppy 7-28 days off therapy
How should Pre-Op Severe HTN (Stage 3 > 180/110) be handled before Eye Surgery?
Reschedule surgery until two weeks of Anti-HTN Treatment
What is the Blood Glucose goal for diabetics regarding Eye Surgery?
BS: 150-250
What Urea Nitrogen level is considered Critical for eye surgery?
> 104 mg/dL
What should be done if a patient came in for Cataract Surgery and was on Coumadin?
Continue with Surgery - safe to do w/ patient on warfarin
What are Eye Surgery Requirements?
Eye Immobility & Lots of Anesthetic at the Site
When should Versed & Fentanyl be avoided for Eye Surgery?
In patients w/ limited cognitive reserve
What kind of Facial Nerve Blocks are typically used prevent eyes from Squeezing & Squinting?
Van Lint
Atkinson
O’Brien
What is a Major Complication from Van Lint, Atkinson, or O’Brien blocks?
Subcantaneous Hemorrhage
What kind of block affects the entire trunk of Facial Nerve and causes Lower Facial Droop for hours post-op?
Nadbath Rehman Block
What are complications related to Nadbath Rehman Blocks?
Vocal Cord Paralysis
Laryngospasm
Dysphagia
Respiratory Distress
How is a Retrobulbar Block done?
Inject 1:1 Bupiv 0.75% + Lidocaine 2% at the Inferior Temporal Margi of the Orbit
What are the effects of a Retrobulbar Block?
Anesthesia of the Globe
Extraocular Akinesia
Hypotony - ↓IOP & ↓Aqueous Humor
What indicates that the Superior Rectus muscle is not affected by the Retrobulbar Block since its outside the muscle cone?
Intorsion on Downward Gaze
What are the complications from a Retrobulbar Block?
Hemorrhage
Proptosis (Downward Displacement)
Subconjuctival Ecchymosis
Optic Nerve Damage
Ocular Perf
Post-Op Strabismus (Cross Eyed)
What happens with Intravascular Injection during a Retrobulbar Block?
Intravenous: Nothing
Arterial: CNS Excitation & Seizure
What can happen when local is injected into the Optic Nerve Sheath/Subarachnoid during a Retrobulbar Block?
Contralateral Amaurosis (Vision Loss)
Obtundation
Respiratory Arrest w/in 20 min
Total Spinal & Vascular Collapse
What are contraindications to a Retrobulbar Block?
Bleeding Disorders
Extreme Myopia (Nearsightedness)
Open Eye Injury
How does a Peribulbar Block compare to a Retrobulbar Block?
Safer
Multiple Injections around Eye
Doesn’t Enter Muscle Cone
Longer Onset
Less Complete Akinesia
Increased Risk of Ecchymosis
What makes a Sub-Tenon’s Block safer than a Peri/Retrobulbar Block?
No sharp needle & Less complications
When is Topical appropriate for Eye Surgery?
Small Incision Surgeries & Phacoemulsion
What are the Disadvantages to using Topical?
Patient Movement
Increased Pt. Anxiety & Discomfort
What is used in Topicals for Eye Surgery?
Tetracaine 0.5%
&
Lidocaine 4%
What meds can be given to limit IOP response to Intubation?
Lidocaine
&
Opioids
What symptom may indicate IO Hypertension, Corneal Abrasion, or other complications?
Severe Pain
What is done to tamponade a detached retina to the globe during certain vitreoretinal procedures?
Inject air bubble into eye
When should N2O be stopped when air bubbles are use to tamponade detacehd retinas?
15 min before Sulfur Hexaflouride & avoid for 7-10 days after to avoid increased IOP
How long should N2O be avoided after the use of Perfluoropropane (C3F6)?
1 Month
How is Lacrimal Surgery done for kids?
Probe & Irrigation - suction well
How is Lacrimal surgery done for Adults?
Dacrocystorhinostomy - Suction well
Which anesthetic is avoided d/t nystagmus?
Ketamine
What type of Anesthesia is used for Retinal Detachment & Vitreal Surgery?
General
or
Retrobulbar BLock
