Ophthalmic and Dental Procedures Flashcards
eye - outer layer
- sclera: white, fibrous
cornea: anterior part of sclera
conjunctiva: outer cover from limbus to eyelid
eye - middle layer
- choroid: located posteriorly, blood supply to retina
- iris: controls light entry by changing pupil size, sympathetic=dilate, parasympathetic=constrict
- ciliary body: secrete aqueous fluid and control shape of lens by tension on zonule of Zinn
*called uveal tract
eye - innermost layer
- retina: converts light impulses to neural impulses
- vitreous gel: attached to blood vessels and optic nerve
caruncle
lacrimal duct
IOP
10-22 mmHg
three chambers of eye
- anterior: cornea to iris, Schlemms Canal is drainage
- posterior: iris to lens, formation
- viterous
myopia versus hyperopia
myopia: nearsighted, eye is long and stretched, focal point close to lens
hyperopia: farsighted, eye is short and, focal point far from to lens
muscles of the eye
- four rectus: controlled by oculomotor (III), lateral controlled by abducens (VI), originate at annulus of Zinn
- two oblique: superior oblique = rotation towards nose by trochlear (IV) inferior oblique = rotation sideways by oculomotor (III)
optic nerve
- CN II
- conveys visual information from retina to occipital lobe
facial nerve
- CN VII
- branches temporal and zygomatic
- controls tears and eye lid
vagus nerve
- CN X
- oculocardiac reflex
ophthalmic artery
- first branch from internal carotid
- medial muscular: medial and inferior rectus, inferior oblique
- lateral muscular: lateral and superior rectus, and superior oblique
- ciliary arteries: short posterior and long posterior
techniques to decrease systemic absorption
- close eyes for 60 seconds
- do not blink
- pressure on tear outflow canal
ocular - cocaine
- DCR procedures
- controls bleeding
ocular - tetracaine
- ester
- onset 1 min
- duration 30 min
- stinging on application
ocular - proparacaine
- ester
- onset 15 sec
- duration 15 min
- less irritation
ocular - hyaluronidase
protein enzyme that speeds onset by promoting even spread of local anesthetic
ocular anesthesia techniques
- MAC with local, topical, or regional
- general anesthesia
ocular blocks - sub-tenon’s capsule
- blunt cannula through small incision in conjunctiva
- contraindicated in glaucoma patients
- better for anticoagulated patients
ocular blocks - retrobulbar
- behind the globe
- may need facial block to prevent blinking
- small volume (2-4 mL)
- fast onset (2 min)
- hemorrhage: proptosis (bulging of eye), subconjunctival hemorrhage, increase IOP - use pressure or lateral canthotomy
ocular blocks - inferotemporal
- transcutaneously
- transconjunctivally
ocular blocks - facial nerve and eyelid block
- orbicularis occuli
- avoid large volume of agent
- complications: facial paralysis, hemorrhage
ocular blocks - peribulbar
- outside of the cone
- larger volume (10-12 mL) = increased risk of IOP
- slower onset (10 min)
Honan device
- diffuse local anesthetic, reduce IOP, soften eye
- 30-40 mmHg for 5 minutes post block
-can manually apply pressure: 30 sec on, 5 sec off
ocular blocks - complications
- oculocardiac reflex
- hemorrhage
- globe puncture
- retinal artery occlusion
- optic nerve penetration
- intravascular injection
ocular blocks - intravascular penetration
-contralateral pupil constricted before injection, dilated after
- painless vision loss
- disorientation
- vomiting
- aphasia
- hemiplegia
- unconsciousness
- convulsions
- arrest
*support cardiac and respiratory systems
ocular blocks - globe puncture
- increased resistance to injection
- immediate dilation
- rapid increase in IOP, than decrease
- edematous cornea
- subconjunctival and intraocular hemorrhage
- pain
- agitation
oculocardiac reflex
- trigeminal (V) afferent, vagus (X) efferent
- bradycardia
- stop surgical simulation and give IV atropine
strabismus
- oculocardiac reflex
- n/v
- avoid succinylcholine = higher risk for malignant hyperthermia
retinal surgery
- sulfur hexafluoride to tamponade the retina
- avoid nitrous oxide
glaucoma
- avoid increases in IOP
- give miotic drugs, avoid mydriatic drugs (atropine gtts, scopolamine)
- acute: painful, treatment with mannitol or acetazolamide
- contraindications: retrobulbar block, awake intubation, succinylcholine
dental procedures
- empty stomach before emergence
- nasal RAE
- **make sure throat packs are removed
