Flashcards in BCSC Plastics Deck (238)
Can MRI be safely performed with a BB in the orbit?
Should BBs be removed from the orbit when found?
Usually, they are best left in place
What are the 5 surgical spaces within the orbit?
1) subperiorbital (subperiosteal) space (a potential space); 2) extraconal space (outside the muscle cone, between the cone and the periorbita); 3) episcleral (sub-Tenon) space (between Tenon capsule and globe); 4) intraconal space (inside muscle cone); 5) subarachnoid space (between optic nerve and nerve sheath)
Which type of orbitotomy incision provides the best cosmetic result when attempting to access the supraorbital rim?
An upper eyelid crease incision (rather than an incision directly over the superior orbital rim)
What approach is now usually used to perform an orbital decompression?
Transconjunctival incision with lateral cnatholysis to disinsert and evert the lower eyelid for exposure of the inferior and lateral orbital rims. This incision can be extended superonasally with a transcaruncular approach to access the medial orbital wall for bone removal and decompression
If used in orbital surgery, how long is a drain generally kept in place
no more than 24-36 hours
Should visual acuity be checked frequently after orbital surgery?
Yes, especially in the first 12 hours after surgery
Should patching of the operative site be performed after orbital surgery?
No, since this can delay diagnosis of postoperative hermorrhage
In which situations is enucleation the anophthalmic surgery of choice?
If the nature of intraocular pathology is unknown or if ocular tumor is suspected
What is a benefit of enucleation over evisceration?
Lower likelihood of sympathetic ophthalmia, particularly with severely traumatized eyes
Which are the ocular tumors that most commonly require enucleation?
Retinoblastoma and choroidal melanoma
What are common indications for enucleation?
1) intraocular malignancy not amenable to alternative modes of therapy such as external-beam radiation or episcleral plaque brachytherapy; 2) blind eyes with opaque media and no known cause of ocular disease; 3) blind painful eyes; 4) severely traumatized eyes without hope for visual recovery
What surgical approaches can be used for obtaining exposure for enucleation?
lateral canthotomy or superomedial approach
What are the components of an acceptable enucleation?
1) orbital implant of sufficient volume; 2) socket lined with conjunctiva or other mucous membrane; 3) eyelids with normal appearance and adequate tone; 4) good transmission of motility from implant to prosthesis; 5) comfortable ocular prosthesis that looks similar to the normal eye
What is the value of a dermis-fat graft for an enucleation performed in a child?
The dermis-fat graft grows in children providing necessary pressure to promote orbital growth
What are the advantages of evisceration?
1) less disruption of orbital anatomy; 2) good prosthesis motility (EOMs remain attached to sclera); 3) preferred treatment in some cases of endophthalmitis; 4) technically simpler than enucleation; 5) lower rates of migration, extrusion, and reoperation than enucleation
What are the disadvantages of evisceration when compared to enucleation?
1) not indicated if ocular tumor suspected or in patients with severe pthisis; 2) theoretically increased risk of sympathetic ophthalmia; 3) provides less complete pathologic specimen than does enucleation
What are the functions of an orbital implant?
1) replace lost orbital volume; 2) maintain structure of the orbit; 3) impart motility to the overlying ocular prosthesis
What are the different classes of spherical orbital implants?
Inert (glass, silicone, MMA) and Biointegrated (hydroxyapatite, porous polyethylene)
What are possible locations for orbital implants?
Within the Tenon capsule or behind the posterior Tenon capsule in the muscle cone
When is an ocular prosthesis usually fitted after anophthalmic surgery?
What are common complications of anophthalmic surgery?
1) deep superior sulcus due to decreased orbital volume; 2) contracture of fornices; 3) exposure and extrusion of the implant; 4) contracted socket; 5) anophthalmic ectropion; 6) anophthalmic ptosis; 7) lash margin entropion
What are circumstances in which exenteration may be appropriate?
1) destructive tumors extending into the orbit; 2) intraocular melanomas or retinoblastomas extending outside the globe but without distant metastases; 3) malignant epithelial tumors of the lacrimal gland; 4) sarcomas not responding to nonsurgical therapy; 5) fungal infection (orbital zygomycosis)
What are the types of orbital exenteration?
Subtotal, Total, and Extended
What are the 5 structural planes of the face?
1) Skin; 2) Subcutaneous tissue; 3) Superficial musculoaponeurotic system (SMAS) and mimetic muscles; 4) deep facial fascia; 5) plane containing the facial nerve, parotid duct, and buccal fat pad
How are the mimetic muscles divided?
Upper face and lower face (superficial and deep)
Which muscles animate the forehead and glabella?
frontalis, corrugator, and procerus
Which muscle depresses the eyebrows and closes the eyelids?
Which muscle elevates the eyebrows?