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describe the type of drape used to fit the eye
adhesive backed, clear, aperture or incisable drapes
describe a loop
an instrument used by the surgeon that are mounted on a pair of glasses and are used for magnification
what is the purpose of Weck-Cel sponges
to help suck up fluid/blood in eye surgery
why are powder free gloves typically used for eye surgery
the powder from the gloves can create corneal irritation
what is a caliper used for
measuring the incision or open the incision more in preparation of placing a lens
to measure the distance from the original point of insertion to the new one
to verify the correct size of the cornea
describe how draping is completed for a procedure that enters the ocular orbit
adhesive-backed, clear, aperture or incisable drape that covers the patients head and upper body
how can you prevent damage or lint when placing microinstrumentation on your Mayo stand
covering the Mayo stand with a clear, plastic, sterile x-ray cassette cover reduces dust on the instruments as well as reduces the risk of microinstrument damage
how is the eye stabilized while the surgeon works on it
a Flieringa ring is sutured on the patient's eye with a 5-0 or 6-0 nylon
4-0 sutures
4-0 silk sutures are placed in the superior rectus muscle for traction
glaucoma: what fluid is affected and where
glaucoma-raised intraocular pressure or IOP
the inability of the aqueous fluid to exit the eye at the correct angle due to blockage by the iris which can damage the optic nerve and retinal blood supply, resulting in loss of vision
glaucoma: what canal is blocked, causing an increase in intraocular pressure (IOP)
the canal of Schlemm (or a weakening of the trabecular meshwork)
glaucoma: why does the increase in IOP lead to blindness
it applies pressure to the optic nerve and damage to the retinal blood supply which leads to ischemia and death of the nervous layer
iridectomy
the surgical removal of a portion of the tissue of the iris: it creates a small hole in the peripheral portion of the iris to connect the posterior and anterior chambers of the eye, permitting the iris to fall back away from the trabecular meshwork, opening the angle of the anterior chamber to allow the outflow of the aqueous fluid through the Schlemm canal
trabeculectomy
surgical creation of an opening that allows aqueous humor to drain out of the eye to underneath the conjunctiva where it is absorbed
describe Tenon's capsule, the purpose of the capsule, and how it is incised
a thin membrane which envelops the eyeball from the optic nerve to the limbus, separating it from the orbital fat and forming a socket in which it moves
the Tenon capsule, also known as fascia bulbi or bulbar sheath, functions as an extraocular muscle pulley. it also provides a socket which separates the globe from the surrounding fat and allows free movement
Tenon's capsule is dissected free from the sclera with forceps and Westcott scissors toward the limbus to create a Tenon capsule-conjuctiva flap
what are the drugs 5-FU and mitomycin used for? how are they used?
5-FU and mitomycin are antimetabolites and must be disposed of as hazardous waste due to their toxicity
5-FU is fluorouracil (a chemotherapy agent)
mitomycin is an antibiotic
the surgeon may use a soaked sponge left in place 1-5 minutes then removed
describe what happens when a retinal detachment occurs
the liquid in the vitreous cavity passes through a retinal tear, separating the retina from the choroid
identify and describe the procedure used to treat retinal tears
scleral buckling procedure
a) diagram
b) diathermy to mark area
c) sponge sutured in place
d) silastic band to support buckle
e) incisions in sclera and choroids to facilitate drainage of subretinal fluid
how are cryotherapy and diathermy used in the treatment of a retinal detachment
diathermy marks areas of tears
cryotherapy seals the tears
what intraocular gases may be used in the treatment of retinal tears
an intraocular gas may be injected to create pressure on the retina; long-acting gases require special head posture from a few days up to two weeks
types of gases include:
perfluoropropane (C3F8)
Sulfur hexafluoride (SF6)
what is the purpose of the intraocular gas that may be injected during the procedure for retinal tears
to create pressure on the the retinato push it back into place while subretinal fluid is reabsorbed and scars form
why would a vitrectomy be performed with this procedure (retinal detachment)
to remove the blood so that the surgeon can view whether a retinal tear or detachment has occurred
where is the incision for a vitrectomy made
a sclerotomy is performed into the globe through the pars plana aka vascular tunic
what else can be used to replace the vitreous humor
silicone oil, intraocular gases, viscoelastic agents (Viscoat, Healon)
gaseous or liquid
intraocular gases
silicone oil
endophotocoagulation
lensectomy
Sodium hyaluronate
saline
what is the vitrector used for
vitrector units can infuse, cut, and aspirate
a tool used to cut the vitreous humour for subsequent removal during a vitrectomy
list three indications for enucleation
an excision of an eye due to:
1. malignant neoplasm
2. penetrating wounds
3. extensive damage where no vision can be regained
describe the difference between enucleation and evisceration. identify which one has better cosmetic effects
enucleation is excision of the eye. attachments of the globe are seperated. optic nerve is transected
evisceration allows the retention of the sclera and extrinsic muscles of the eye. it eliminates corneal sensitivity and allows the patient to wear a prosthetic eye that will have mobility and a better cosmetic result
what types of implants may be used? why is a donor sclera sometimes used?
ocular implant
hydroxyapatite implant
donor sclera is used to create a flap in glaucoma filtering procedures. this simple technique is helpful when the sclera is too thin to safely and effectively form an adequate scleral flap. the use of donor sclera allows the procedure to continue as a guarded procedure and prevents early postoperative hypotony.
describe three reasons for cataract formation
1) age
2) trauma
3) exposure to harmful chemicals
4) drugs
5) exposure to excessive sunlight
6) congenital disease
describe the formation of a cataract and the symptoms it causes
the lens gradually clouds, less light is able to pass through, blurring and distorting images received by the retina, vision is gradually impaired, untreated causes needless blindness
may be white or yellow or brown
may form in nucleus of lens, outer cortical region, or entire lens
describe two methods of cataract extraction
intracapsular cataract extraction: involves a large incision and the entire capsule is removed; suturing is required for closing the incision
extracapsular cataract extraction: performed through a small incision and only the lens is removed; incision is self-sealing with no sutures required
describe the incision made for cataracts that is self-healing
extracapsular cataract extraction: performed through a small incision and only the lens is removed; incision is self-sealing with no sutures required
where is the corneal limbus?
the border of the cornea and the sclera (the white of the eye). The limbus is a common site for the occurrence of corneal epithelial neoplasm. The limbus contains radially-oriented fibrovascular ridges known as the palisades of Vogt that may harbour a stem cell population.[1] The palisades of Vogt are more common in the superior and inferior quadrants around the eye.[2] Aniridia, a developmental anomaly of the iris, disrupts the normal barrier of the cornea to the conjunctival epithelial cells at the limbus.
phacoemulsification (PHACO) may be used. describe how the machine works
a variation of the irrigation/aspiration technique. the tip of the phaco handpiece is inserted through the small incision and ultrasonic energy fragments the lens while simultaneously irrigating and aspirating the fragments. after the nucleus of the lens is removed, the irrigating/aspirating unit is used to remove the remaining pieces of cortex
what is acetylcholine used for? what classification does that make acetylcholine?
injected into the anterior chamber through a fine cannula (30 gauge) at the graft margin (during a keratoplasty aka corneal transplant)
a compound that occurs throughout the nervous system, in which it functions as a neurotransmitter
describe the purpose of the cornea
the cornea allows light into the eye and bends the light rays to help the lens focus them upon the retina
describe four causes of corneal clouding
1) eye injuries
2) bacterial, biral, or fungal infections
3) corneal dystrophies
4) cataract or other eye surgery
what type of instrument is a trephine and what procedure is it used for
a cylindrical saw for cutting a circular piece of bone
used in corneal procedures
how long can the donor cornea be stored
up to 14 days
how can you ensure proper fit of the cornea during a keratoplasty
the donor cornea is sized 0.1 mm larger than the recipient opening to ensure proper fit. the surgeon may request a separate sterile table for donor cornea preparation
when might rejection of a donor cornea occur
rarely occurs within two weeks and may occur as late as 20 years following corneal transplant
what is the purpose of applying fluorescein to the cornea? what tool must be used in conjunction with fluorescein?
fluorescein is a diagnostic agent used topically to mark tissue
fluorescein is used for detection of corneal abrasion or to access lacrimal duct patency
a diagnostic tool used in diagnosing corneal abrasions, corneal ulcers and herpetic corneal infections.
Woods lamp (ultraviolet light) or black light aids in diagnosis