Exam 2 (Eyes) Flashcards
What structures make up the Uveal tract?
Choroid, Iris, & Ciliary body
What is the purpose of the Choroid?
provides blood flow to the retina
What is the purpose of the Ciliary body?
Produces aqueous humor
What fills the center of the eye?
Vitreous gel
Sympathetic fibers of the Iris originate from?
The carotid plexus
Parasympathetic fibers of the Iris originate from the _____.
oculomotor nerve
Majority of the orbital structures receive blood supply from the _____ artery, a branch of the _____ and the ____ vein drains directly into the ______
Opthalmic artery
internal carotid
opthalmic vein
cavenous sinus
What transmits neural signals from the retina?
Optic (II) nerve
What nerves control extraocular muscle movement?
Oculomotor (III)
Trochlear (IV)
Abducens (VI)
What nerve senses pain & touch for the eye?
Trigeminal (V)
Upper eyelid sensation is innervated by the?
Frontal branch of the ophthalmic nerve
Lower eye sensation is innervated by the?
Maxillary nerve
What is the normal IOP?
10 - 20 mmHg
What regulates IOP?
Resistance at the trabecular meshwork
What causes chronic pressure elevation in open-angle glaucoma?
Sclerosis of the trabecular meshwork
What causes the most significant increases in IOP?
Intubation & emergence
Coughing, straining, & vomiting cause an IOP increase of about?
30 - 40 mmHg
What states causes increased IOP?
Hypercapnia
Hypoxia
Hypertension
How does hypercapnia increase IOP?
It causes choroidal congestion
Scc increases IOP by ____ mmHg
8 - 10 mmHg
What block cause the greatest increase in IOP?
Peribulbar block, likely due to volume injected
What anesthesia drugs cause increased IOP?
Neostigmine, atropine, Sux
A normal blink icreases IOP by ___ mmHg & a forceful lid squeeze by ___ mmHg?
10 mmHg
70 mmHg
What drugs decrease IOP?
Volatile & IV anesthetics via relaxation of extraocular muscles
Short-acting opioids
Acetazolamide
Echothiophate (Phospholine Iodide)
Timolol (Timpoptic)
What drugs have no effect on IOP?
Midazolam
Nitrous oxide
NMDAs
Suggamadex
What triggers the Trigeminovagal reflex?
- Traction on the extraocular muscles (the Medial rectus muscle).
- The afferent limb of the reflex limb arises from the ophthalmic division of the trigeminal nerve and travels to the Gasserian ganglion and the sensory nucleus of the trigeminal nerve near the fourth ventricle.
The afferent limb synapses with the motor nucleus of the vagus nerve
What ventilation states worsen the oculocardiac reflex?
Hypercapnia & hypoxia
What condition is characterized by peripheral visual field loss?
Open-angle glaucoma
How does open-angle glaucoma lead to increased IOP?
Increased aqueous humor production and/or decreased outflow
What causes closed-angle glaucoma?
Acute dilation of the Iris –> blocking drainage of fluid
What is the treatment of closed-angle glaucoma?
Iridotomy
What drugs are not given in closed-angle glaucoma?
Scopolamine
Antihistamines & decongestants
Benzos (relax sphincter muscle)
Cocaine, Ecstasy, & marijuana
Ipratropium bromide (Atrovent)
Atropine
Nortriptyline
(lots of -mines & pines)
What is the treatment of the Oculocardiac reflex?
Prevention
Stop surgery
Give atropine 7 - 10mcg/kg IVP
Robinul 0.2mg IVP
Which nerves are blocked with a peribulbar block?
CN III (Oculomotor) & CN VI (Abducens)
When and why is a peribulbar block performed?
- 20mins before Sx
- It is less painful and less increase in IOP
Which nerves are blocked with a retrobulbar block?
CN II (Optic)
CN III (Oculomotor)
CN VI (Abducens)
