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