SUR 104 - ophthalmology
Card Set Information
SUR 104 - ophthalmology
goal of ophthalmologic surgery
restore vision lost as a result of disease, injury or congenital defect
7 bones that come together to form the orbit
where does optic nerve enter?
posterior orbital cavity through optic foramen
what are eyelids composed of?
fibrous connective tissue (tarsal plate)
space or interval between upper and lower lids
juncture of eyelids
secrete waxy oil that seals eyelids when closed
sebaceous glands located along lid margin and in lacrimal caruncle
what do eyelashes do?
protect eye from airborne particles
2 spaces of anterior cavity of globe
anterior and posterior chambers
how many muscles attach sclera to bony orbit?
4 rectus muscles
2 oblique muscles
vision is normally...
what does visible area consist of?
central and peripheral vision
thin, transparent mucous membrane that lines each eyelid and covers sclera
regions of conjunctiva
palpebral and bulbar regions
part of conjunctiva that is highly vascular and pink, lines eyelids and extends over cornea
part of conjunctiva that covers anterior portion of eyeball up to junction of sclera and appears white
clear tissue layer overlying the front of eyeball
3 tissue layers of cornea
where does refraction take place?
in the cornea
where do the tissues of the cornea come together?
initial incision of cataract surgery
at the limbus
thick, white, fibrous tissue that encloses about 3/4 eyeball
what part of the eye communicates with optic nerve sheath?
highly vascular, pigmented layer that lies directly beneath the sclera
primary function of choroid
to prevent reflection of light within eyeball
extension of the choroid layer, located at periphery of anterior choroid
what is the ciliary body composed of?
smooth muscle tissue, to which suspensory ligaments are attached
pigmented membrane composed mainly of muscle tissue that surrounds the pupil
innermost layer of globe
what does the retina do?
it is the photoreceptive layer of the eye
receives and transmits images to the brain via optic nerve
distinct area of acute vision
center of macula
area of dense neurons in which the optic nerve exits the globe
how many photoreceptors does optic disc contain?
clear, biconvex disk contained in a transparent capsule, lying directly behind the iris
how is the lens held in place?
suspensory ligaments called zonules
what fills the anterior chamber of the anterior eye?
aqueous humor (produced by ciliary epithelium)
through what does aqueous humor pass?
through the pupil and into the canal of Schlemm
what is the posterior chamber filled with?
what is vitreous humor?
gel-like substance that nourishes the inner tissue layers, gives shape to the posterior globe and acts as a refractive medium for light
what does the lacrimal apparatus do?
lacrimal apparatus consists of:
opening of each duct of lacrimal apparatus
what are tears composed of?
proteins, mucus, sodium chloride, glucose and enzymes
bending of light rays through a transparent medium
process in which lens continually changes shape to maintain focus of an image on the retina
what is test for visual acuity performed with?
what is a slit lamp used for?
to examine anterior chamber of the eye
what is used to stain the cornea and highlight irregularities of the epithelial surface?
what is used to measure the intraocular pressure?
what is direct examination of the eyes performed with?
what does an ophthalmoscope do?
magnifies the focal point
what is used extensively in the diagnosis and evaluation of retinal and choroid diseases?
what is used to measure the density of eye tissues and detect abnormalities?
what does a B-scan ultrasound do?
produces image of the target tissue that shows a series of spots, brightness of which corresponds to tissue density
what does an A-scan ultrasound do?
depicts tissue density as amplitude on two axes
what tests are used in the evaluation of the orbital and intracranial structures?
MRI and CT
most common cause of cataracts?
inflammation or infection of lacrimal sac
dacryocystitis usually arises from?
obstruction of lacrimal canal
inversion of eyelid (lower lid)
drooping or eversion of eyelid
optic nerve and visual field damage
what is glaucoma usually caused by?
inadequate drainage of aqueous humor - unrelieved pressure damages optic nerve and may result in progressive blindness
degeneration of the rod and cone photoreceptor cells of the retina
most common cause of blindness in people over age 65
age-related macular degeneration (ARMD)
separation or tear in retina, allowing vitreous to seep between layers and delaminate them
inability to coordinate the extraocular muscles
cause of strabismus
weakness of paralysis of muscles
can be congenital or acquired
what condition is a medical emergency that requires surgery?
lens implants are treated in much the same way as?
what type of table is used in most facilities for a patient acquiring ophthalmic surgery?
combination stretcher-operating table because shifting the patient immediately after surgery may result in increased IOP and eye injury
what types of anesthetic is used for most ophthalmic surgeries?
regional block and monitored sedation
antiseptics used for eye prepping
dilute povidone-iodine (5% or as directed by MD) and hexachlorophene
supplies needed for sterile prep setup
plastic towel drapes
lint-free gauze sponges
cellulose eye sponges
balanced salt solution (BSS)
eyelid and margins, inner and outer canthus, brows and face, ending at chin
how is prep solution runoff prevented?
by squeezing excess solution from each sponge and a small piece of cotton placed in operative side ear
type of anesthetic used for pediatric patients
what is lidocaine with epinephrine used for?
to maintain vasoconstriction at the operative site
phenylephrine (Neo-Synephrine, Mydfrin)
what do mydriatic drugs do?
dilate the pupil
what are mydriatic drugs used for?
examination of the retina
testing of refraction
easier removal of lenses
what does atropine do?
dilates pupil, inhibits focusing, anticholinergic, potent
long duration of action (7-14 days)
what does epinephrine do?
dilates pupil, added to BSS for irrigation to maintain pupil dilation during cataract surgery or vitrectomy
acetylcholine chloride (Miochol-E)
what do miotic drugs do?
used intraocularly during anterior segment surgery
onset of topical anesthetics
duration of action of topical anesthetics
bupivacaine (Marcaine, Sensorcaine)
onset and duration of lidocaine
onset - 4-6 min
duration - 40-60 min, 120 min with epinephrine
onset and duration of bupivacaine
onset - 5-11 min
duration - 8-12 hours with epinephrine
onset and duration of mepivacaine
onset - 3-5 min
duration - 2 hour (longer with epinephrine)
additives to local anesthetics
epinephrine (prolongs anesthesia and reduces bleeding)
Healon in sterile syringe assembly
what is Healon used for?
lubricant and support
maintains separation between tissues to protect endothelium, maintain anterior chamber intraocularly and prevent postoperative increase in pressure
requirements for Healon use
should be refrigerated
allow 30 min to warm to room temp
BSS - used to keep the cornea moist during surgery
mannitol (Osmitrol) - reduces IOP
betamethasone sodium phosphate and betamethasone acetate suspension (Celestone) - prophylaxis
what is cocaine used for?
used on cornea to loosen epithelium before debridement and on nasal packing to reduce congestion of mucosa
what is fluorescein used for?
IV - diagnose retinal disorders
topical - stains cornea
2 types of ESU systems commonly used in eye surgery
single-use, battery-powered cautery
handheld battery ESU has?
very small filament tip that becomes hot when the unit is activated
what does the filament of handheld ESU do?
coagulates very small vessels of the eye, but does not cut
when is bipolar ESU used?
procedures in which fine cutting and coagulation are required
what are eye sponges made of?
is sponge used on cornea?
how does the sponge absorb fluid?
by wicking - done by holding the tip of the sponge in contact with the fluid and allowing the sponge to absorb it
eye suture sizes
from 4-0 to 12-0
how should eye sutures be handled?
as little as possible
types of sutures frequently used to close circumferential incisions
procedure in which nodal tissue arising from a sebaceous gland is excised from the tarsal plate
inflammatory, benign growth that originates in sebaceous gland of eyelid
how is chalazion excision performed?
lid is everted and vertical incision is made through tarsal plate
goal of entropion repair
restore eyelid to correct anatomical position by resection
what is entropion caused by?
weakness and imbalance of eyelid muscles
goal of ectropion repair
restore eyelid to normal position
how is ectropion repair performed?
wedge of tissue is removed from lower tarsal plate and canthal tendon is secured to periosteum of orbital rim
cause of ectropion
goal of pterygium repair
membrane is surgically removed to prevent loss of vision
patch of degenerative elastic tissue that proliferates from the conjunctiva in response to chronic irritation
pterygium - appears as a white or yellowish vascular mass
when is pterygium surgery indicated?
when documented growth has occurred, lesion is close to the visual axis or vision is impaired
creation of permanent opening in tear duct for drainage of tears
inflammation of lacrimal sac, causing pain, redness and swelling of medial canthus
2 groups of patients in which lacrimal sac inflammation and infection usually are seen
adults over age 40
goal of dacryocystorhinostomy
reestablish drainage into lacrimal duct system
alternative method of dacryocystorhinostomy
stent with silicone tubing
goal of lacrimal duct probing
lacrimal duct is opened and obstruction is removed
most common sign of abnormality of lacrimal system
how is punctum checked for patency during lacrimal duct probing?
with a 2-mL syringe and cannula
what is done if lacrimal duct probing does not relieve obstruction?
silicone tube may be implanted
goal of muscle resection and muscle recession
correct deviation of the eye caused by strabismus
2 procedures commonly used to treat strabismus
lateral rectus resection
medial rectus recession
what is done in lateral rectus resection?
portion of the muscle is excised and the severed end is reattached at the original site of insertion, limiting the drift of the eye
what is done in medial rectus recession?
muscle is detached from its insertion, moved posteriorly, and reattached, releasing the eye and allowing it to move farther in lateral position
during muscle resection/recession, what can traction on the muscles cause?
vagal response, resulting in bradycardia
surgeon will then temporarily release traction on muscles
full-thickness transplantation of donor cornea to restore vision
most common causes of corneal opacification
chemical and thermal burns
2 types of corneal transplantation
lamellar (partial penetrating)
goal of LASIK surgery
shape curvature of the cornea and correct refractory problem
what is LASIK surgery performed with?
anterior-posterior distance of the globe is too short
images that are close are blurred because focal point is behind retina
anterior-posterior distance of the globe is too long
focal point lies in front of retina
uneven curvature of refractive medium
activities after LASIK surgery
avoid activities requiring bending or kneeling for the first week after surgery
fragmentation of tissue by ultrasonic vibration
most common form of cataract removal
goal of cataract extraction
remove opaque lens and replace with an intraocular lens implant to restore vision
what is instilled into the eye during cataract prep for antibacterial effect?
what complication is most common in the first 2-3 days after cataract surgery?
blood in the anterior chamber of the eye
goal of anterior vitrectomy
to remove vitreous from anterior chamber, for example if vitreous is overhydrated during cataract surgery
major complication of vitrectomy
when is scleral buckling performed?
when sensory layer of retina becomes separated from pigment epithelial layer
what does a tear in the retina cause?
sudden, painless loss of vision or "shadowing" (like a curtain) with often light flashes and floaters
what is a tear in the retina called?
how is retinal detachment repaired?
adhesions are produced between the layers using cryotherapy or diathermy, followed by scleral buckling
what is involved in scleral buckling?
Silastic or foam band is attached to the sclera
synthetic buckles are placed over the band, causing it to indent and puts the tissue in close contact with retina during healing
what is done when vitrectomy is performed in conjunction with scleral buckling?
vitreous gel is replaced with Healon or gas through small puncture wound - used to eliminate traction and tearing on the retina
what does intravitreous gas injection do?
exerts pressure on the retina while subretinal fluid is reabsorbed
gases that are injected intravitreously
why is trabeculectomy performed?
to create a channel from which the aqueous humor may drain from the anterior chamber for the treatment of glaucoma
group of diseases characterized by optic nerve damage and visual field loss
IOP is normally maintained by what?
type of glaucoma with sudden rise in IOP caused by total blockage or obstruction of aqueous humor at root of iris
primary angle closure glaucoma
type of glaucoma that occurs in both eyes in which outflow of aqueous humor is obstructed in trabecular meshwork
primary open angle glaucoma
subtype of open angle glaucoma in which intraocular pressure is normal, there is retinal damage and visual field loss with migrain and optic disc hemorrhage
normal tension glaucoma
type of glaucoma in which the fluid drainage system is abnormal at birth - infant's eye distends and corneal haziness occurs
goal of argon laser trabeculoplasty
shrink collagen and stretch canal of Schlemm, expanding canal, increasing drainage and reducing IOP
most common complication of laser surgery for glaucoma
increase in pressure in the eyes
goal of orbital decompression
one or more bony sections of orbital cavity are removed to reduce pressure on optic nerve
indications for orbital decompression
to treat hyperthyroidism (Graves' disease)
to treat pressure on optic nerve caused by tumor or swelling
most common approach to orbital decompression
through the lower lid
complete removal of eyeball
procedure in which contents of the eye are removed, but outer shell of the sclera and muscle attachments are left intact
indications for enucleation
intraocular malignancy, penetrating ocular wound, painful blind eye, painless, disfigured blind eye
implant that is inserted to shape orbital cavity
placed over sphere and covers its surface
most common orbital implant materials
removal of entire eye and orbital contents, including eyelids, ocular muscles and orbital fat
indications for orbital exenteration
cancer, only after all other therapies have failed