RAPID REVIEW Flashcards
A child is accidentally shot in the eye with a gun. What type of imaging procedure should be performed to localize the foreign body
CT scan is the procedure of choice to locate an intraocular or intraorbital metallic foreign body.
A MRI scan is contraindicated if a metallic foreign body is suspected because the strong magnetic field could cause movement of the foreign body and additional injury.
How is levator function evaluated?
The patient is asked to look up and down and the excursion of the upper eyelid is measured.
What is normal levator function?
Approximately 13 mm or more of eyelid excursion.
What is good levator function?
Approximately 8 to 13 mm of movement.
What is poor levator function?
Less than 4 mm of eyelid movement.
Why is it important to know the levator function of an eyelid?
Levator function determines the type and amount of surgery that need to be performed.
Eyelid sling procedures are generally used for what amount of levator function?
Less than 4 mm.
In the transconjunctival approach to lower eyelid blepharoplasty, is the orbital septum incised?
The palpebral conjunctiva and lower eyelid retractors are incised. The orbital septum is anterior to the extraconal fat in the eyelid and is not incised.
What structures are encountered if one makes an incision 1 cm above the
upper tarsus?
Skin, orbicularis muscle, orbital septum, orbital fat, levator aponeurosis, Müller’s muscle, conjunctiva.
Why is it important to incise the orbital septum when performing surgery on the levator aponeurosis for ptosis repair?
The levator aponeurosis is posterior to the pre-aponeurotic fat. In order to adequately expose the aponeurosis, the septum must be incised and the pre-aponeurotic fat gently dissected from the anterior surface of the aponeurosis.
A 3-year-old patient present with unilateral congenital ptosis. The eyelid margin bisects the visual axis and the levator function appears to be 3 mm. What surgical procedure is indicated to correct this ptosis?
A fascia lata sling with either autogenous or banked fascia.
What would be the procedure of choice if the levator function were 7 mm instead of 3 mm?
A levator resection.
How is the amount of resection determined for ptosis cx?
It is based both on the amount of ptosis and the levator function. Tables exist for determining the exact amount of resection. In general, 6 to 7 mm of aponeurosis and muscle should be excised to correct each 1 mm of ptosis.
What is the embryologic origin of the orbital bones?
Cranial neural crest cells.
A 75-year-old patient presents with slowly progressive unilateral ptosis of unknown duration. Examination of the involved eye reveals a margin reflex distance-one of 0 mm, levator function of 17 mm, and a margin crease distance of 14. What is the origin of this ptosis?
Dehiscence of the levator aponeurosis. This is a classic presentation for age-related aponeurotic ptosis.
When should skin sutures be removed from areas of good blood supply (i.e.
face and neck)?
Within 4 to 5 days.
What is the absorption rate of chromic gut sutures?
20 days.
A 30-year-old patient complains of a bump in his left upper lid. An umbilicated, dome shaped nodule with multiple whitish inclusions is found on the lid, and a follicular conjunctivitis is present. What is the treatment and what will histopathology of the lesion show?
The patient has molluscum contagiosum. The treatment of choice is excision biopsy or curettage of the lesion. Antiviral agents are not effective in the treatment of these lesions. The histopathology will show large eosinophilic intracytoplasmic inclusion bodies.
What are the most common complications of ptosis surgery?
Overcorrection, undercorrection, corneal exposure due to lagophthalmos, abnormal
eyelid crease, abnormal eyelid conformation and curve, eyelash loss.
What is the most common cause of bilateral proptosis in adults?
Thyroid orbitopathy.
What is the importance of the neosynephrine test in evaluating age-related ptosis?
The neosynephrine test using either 2.5% or 10% neosynephrine is a test of Müller’s muscle (superior tarsal muscle) function.
A positive response (eyelid elevation) is essential if a conjunctiva-Müller’s muscle excision is to be utilized to repair the ptotic eyelid.
What are the most common procedures to correct age-related ptosis with good levator function?
Aponeurosis repair and/or resection, Conjunctiva-M ̧llerís muscle excision, and tarsectomy (Fasanella-type procedure)
What is the upper lid retraction produced by Grave’s disease due to?
Overreaction of Müller’s muscle.
If a pin is inserted into the upper eyelid 4 mm above the lashes, what eyelid structures are encountered from anterior to posterior?
Skin, orbicularis muscle, levator aponeurosis, tarsus, and conjunctiva.
In unilateral congenital ptosis requiring a fascia lata sling, should any
procedure be performed on the opposite normal eye?
Either nothing, in which case the asymmetrical POP appearance and function should be explained to the patient and his/her family or a sling procedure can be placed in the normal side to achieve symmetry between the two sides.
Where is the valve of Hasner located?
Underneath the inferior turbinate of the nose.
Do pleomorphic adenomas of the lacrimal gland have a true capsule?
They are not truly encapsulated, but compression of surrounding orbital tissues occurs which can simulate a capsule.
What innervates Müller’s muscle?
Müller’s muscle, which elevates the upper lid about 2 mm, is innervated by the sympathetic system.
An ill-appearing patient presents with a fever of 104o F, bilateral chemosis, III nerve palsy and a history of sinusitis. What is the most likely diagnosis?
Cavernous sinus thrombosis.
If a pin is inserted into the upper eyelid 10 mm above the lashes in the area of the eyelid crease, what structures are encountered from anterior to posterior?
Skin, orbicularis muscle, levator aponeurosis, Müller’s muscle, and conjunctiva.
What are Touton giant cells?
Touton giant cells have a central zone of eosinophilic cytoplasm surrounded by an inner ring of multiple nuclei and an outer clear zone containing lipid. They are usually found in lipid granulomas or xanthomas of diseases such as juvenile xanthogranuloma and fibrous histiocytoma.
What infectious organism is the most common cause of chronic canaliculitis?
Actinomyces
What is the treatment for jaw-winking ptosis with fair levator function?
Excision of the levator aponeurosis and fascia lata sling ptosis correction.
What infectious organisms are the most common causes of acute dacryocystitis?
S. pneumoniae, staphylococcus and H. influenza
What are the main clinical features of an orbital blowout fracture?
- Periocular signs, eg. Ecchymosis, edema and subcutaneous emphysema.
- Infraorbital nerve anesthesia.
- Enophthalmos.
- Diplopia.
Are most medial wall orbital blowout fractures associated with a floor fracture?
Yes. Isolated medial wall fractures are relatively rare. Entrapment of the medial rectus can give rise to defective adduction and abduction.
What are the indications for surgical intervention in a patient with a blowout fracture?
Surgical repair is performed 10-14 days after the injury if the patient has persistent diplopia when looking straight ahead or when attempting to read, if he has unacceptable enophthalmos or if a large fracture involving half or more of the orbital floor is present.
In which Le Fort fractures is CSF rhinorrhea commonly seen?
Le Fort II and III.
What is the significance of visualizing a large vascular channel at the superior tarsal border during ptosis surgery from via a skin approach?
The vessel is the peripheral arterial arcade traveling beneath the levator aponeurosis and on the surface of Müller’s muscle. When this vessel is visualized, the levator aponeurosis is dehisced.
What sling materials should be considered in an adult with chronic progressive external ophthalmoplegia?
A silicone rod will allow the eyelid to close more easily. Patients with CPEO and similar diseases such as myasthenia gravis may have decreased orbicularis muscle function.
What other procedures can be used to elevate the eyelids in patients with poor levator function and decreased orbicularis function?
A Fasanella-type tarsectomy or a small levator resection is useful for minimally elevating the eyelids in these patients. Some surgeons advocate blepharoplasty alone so as not to compromise eyelid closure.
What nerves pass through the superior part of the superior orbital fissure?
Lacrimal nerve.
Frontal nerve.
Trochlear nerve (CN IV).
How many millimeters above the superior tarsal border can Whitnall’s (superior transverse) ligament be visualized?
Approximately 15 to 20 mm.
What nerves pass through the inferior part of the superior orbital fissure?
Oculomotor nerve (CN III).
Abducens nerve (CN VI).
Nasociliary nerve (CN V).
What is acanthosis?
It is an increase in the prickle cell layer due to increase in mitotic activity of the basal cells.
In the immediate postoperative period what are the appropriate management options for overcorrected ptosis?
Suture release, downward eyelid massage, and eyelid stretching over a Desmarres retractor.
In the late POP period what surgical procedure is usually performed to correct overcorrected ptosis?
Levator recession and scar release. These procedures can be performed either from a posterior or anterior approach.
How many extraconal fat compartments are present in the upper eyelid and how many in the lower eyelid?
There are two extraconal fat compartments in the upper eyelid and three in the lower. The lacrimal gland substitutes for the lateral fat compartment in the upper eyelid.
What is the most common type of rhabdomyosarcoma in children?
Embryonal rhabdomyosarcoma.
Which type of rhabdomyosarcoma has the worst prognosis?
Alveolar type.
Where are the most common locations for rhabdomyosarcoma in the orbit?
Retrobulbar followed by superior and inferior.
What part of the orbit does alveolar rhabdomyosarcoma usually present?
Inferiorly.
What does a CT scan of rhabdomyosarcoma reveal?
CT shows a poorly defined mass of homogeneous density, adjacent bony destruction and
invasion of paranasal sinuses.
What is the management for rhabdomyosarcoma?
Biopsy to confirm the diagnosis, followed by radiotherapy and chemotherapy.
Which is the weakest wall in the orbit?
The medial wall is the weakest orbital wall. It includes the lamina papyracea of the ethmoid bone, the thinnest bone in the orbit, which predisposes it to fractures and secondary orbital infections due to ethmoidal sinusitis.
What is the origin of the upper eyelid crease and fold?
Fibers of the levator aponeurosis inserting into the subcutaneous tissues just inferior to the orbital septum. The skin above the crease is less firmly attached to the underlying tissues than the skin below the crease allowing it to fold over the crease when the eyelid is open.
What is the surgical significance of the eyelid crease?
The normal adult crease is 10-12 mm above the eyelid margin and is where the upper eyelid incision should be made during ptosis and blepharoplasty procedures to hide the incision postoperatively. A high eyelid crease usually indicates a levator aponeurosis dehiscence.
What is the cause of involutional ectropion?
Eyelid laxity.
What are the underlying pathologies for involutional lower eyelid entropion?
Horizontal eyelid laxity, dehiscence of the capsulopalpebral fascia, and pre-septal orbicularis muscle hypertrophy.
Is bilateral inflammatory pseudotumor more common in children or in adults?
Unilateral involvement is the rule in adults, while in children bilateral involvement occurs in 30%. In adults, a careful evaluation should be performed to rule out a systemic vasculitis and lymphoma.
Where is the most common location for an orbital meningocele?
Above the medial canthus.
What is the most common form of congenital ptosis?
Myogenic congenital ptosis is the most common form and results in a fibrotic levator muscle with or without fat infiltration that is unable to function.
A child with a sinus infection presents with left proptosis, swollen eyelid and an inferolaterally displaced globe. What is the most likely diagnosis?
Orbital cellulitis and abscess associated with ethmoid sinusitis.
What is the most common bacterial agent likely to lead to orbital cellulitis and CNS infection in infants and young children?
H. influenzae.
What is the most common bacterial agent implicated in orbital cellulitis in adults?
Staphylococcus.
What are the potential complications of orbital cellulitis?
Intracranial complications: cavernous sinus thrombosis, brain abscess, and meningitis.
Subperiosteal abscess.
Ocular: exposure keratitis, optic nerve inflammation, increased IOP, retinal vascular occlusion.
At what age group does capillary hemangioma usually present?
During the first year of age. More than 50% are present by the first two months of life.
What systemic disease may be associated with congenital encephaloceles?
Neurofibromatosis type 1.
