RAPID REVIEW Flashcards
(171 cards)
1
Q
A child is accidentally shot in the eye with a gun. What type of imaging procedure should be performed to localize the foreign body
A
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.
2
Q
How is levator function evaluated?
A
The patient is asked to look up and down and the excursion of the upper eyelid is measured.
3
Q
What is normal levator function?
A
Approximately 13 mm or more of eyelid excursion.
4
Q
What is good levator function?
A
Approximately 8 to 13 mm of movement.
5
Q
What is poor levator function?
A
Less than 4 mm of eyelid movement.
6
Q
Why is it important to know the levator function of an eyelid?
A
Levator function determines the type and amount of surgery that need to be performed.
7
Q
Eyelid sling procedures are generally used for what amount of levator function?
A
Less than 4 mm.
8
Q
In the transconjunctival approach to lower eyelid blepharoplasty, is the orbital septum incised?
A
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.
9
Q
What structures are encountered if one makes an incision 1 cm above the
upper tarsus?
A
Skin, orbicularis muscle, orbital septum, orbital fat, levator aponeurosis, Müller’s muscle, conjunctiva.
10
Q
Why is it important to incise the orbital septum when performing surgery on the levator aponeurosis for ptosis repair?
A
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.
11
Q
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
A fascia lata sling with either autogenous or banked fascia.
12
Q
What would be the procedure of choice if the levator function were 7 mm instead of 3 mm?
A
A levator resection.
13
Q
How is the amount of resection determined for ptosis cx?
A
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.
14
Q
What is the embryologic origin of the orbital bones?
A
Cranial neural crest cells.
15
Q
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?
A
Dehiscence of the levator aponeurosis. This is a classic presentation for age-related aponeurotic ptosis.
16
Q
When should skin sutures be removed from areas of good blood supply (i.e.
face and neck)?
A
Within 4 to 5 days.
17
Q
What is the absorption rate of chromic gut sutures?
A
20 days.
18
Q
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?
A
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.
19
Q
What are the most common complications of ptosis surgery?
A
Overcorrection, undercorrection, corneal exposure due to lagophthalmos, abnormal
eyelid crease, abnormal eyelid conformation and curve, eyelash loss.
20
Q
What is the most common cause of bilateral proptosis in adults?
A
Thyroid orbitopathy.
21
Q
What is the importance of the neosynephrine test in evaluating age-related ptosis?
A
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.
22
Q
What are the most common procedures to correct age-related ptosis with good levator function?
A
Aponeurosis repair and/or resection, Conjunctiva-M ̧llerís muscle excision, and tarsectomy (Fasanella-type procedure)
23
Q
What is the upper lid retraction produced by Grave’s disease due to?
A
Overreaction of Müller’s muscle.
24
Q
If a pin is inserted into the upper eyelid 4 mm above the lashes, what eyelid structures are encountered from anterior to posterior?
A
Skin, orbicularis muscle, levator aponeurosis, tarsus, and conjunctiva.
25
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.
26
Where is the valve of Hasner located?
Underneath the inferior turbinate of the nose.
27
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.
28
What innervates Müller’s muscle?
Müller’s muscle, which elevates the upper lid about 2 mm, is innervated by the sympathetic system.
29
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.
30
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.
31
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.
32
What infectious organism is the most common cause of chronic canaliculitis?
Actinomyces
33
What is the treatment for jaw-winking ptosis with fair levator function?
Excision of the levator aponeurosis and fascia lata sling ptosis correction.
34
What infectious organisms are the most common causes of acute dacryocystitis?
S. pneumoniae, staphylococcus and H. influenza
35
What are the main clinical features of an orbital blowout fracture?
1. Periocular signs, eg. Ecchymosis, edema and subcutaneous emphysema.
2. Infraorbital nerve anesthesia.
3. Enophthalmos.
4. Diplopia.
36
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.
37
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.
38
In which Le Fort fractures is CSF rhinorrhea commonly seen?
Le Fort II and III.
39
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.
40
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.
41
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.
42
What nerves pass through the superior part of the superior orbital fissure?
Lacrimal nerve.
Frontal nerve.
Trochlear nerve (CN IV).
43
How many millimeters above the superior tarsal border can Whitnall’s (superior transverse) ligament be visualized?
Approximately 15 to 20 mm.
44
What nerves pass through the inferior part of the superior orbital fissure?
Oculomotor nerve (CN III).
Abducens nerve (CN VI).
Nasociliary nerve (CN V).
45
What is acanthosis?
It is an increase in the prickle cell layer due to increase in mitotic activity of the basal cells.
46
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.
47
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.
48
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.
49
What is the most common type of rhabdomyosarcoma in children?
Embryonal rhabdomyosarcoma.
50
Which type of rhabdomyosarcoma has the worst prognosis?
Alveolar type.
51
Where are the most common locations for rhabdomyosarcoma in the orbit?
Retrobulbar followed by superior and inferior.
52
What part of the orbit does alveolar rhabdomyosarcoma usually present?
Inferiorly.
53
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.
54
What is the management for rhabdomyosarcoma?
Biopsy to confirm the diagnosis, followed by radiotherapy and chemotherapy.
55
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.
56
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.
57
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.
58
What is the cause of involutional ectropion?
Eyelid laxity.
59
What are the underlying pathologies for involutional lower eyelid entropion?
Horizontal eyelid laxity, dehiscence of the capsulopalpebral fascia, and pre-septal orbicularis muscle hypertrophy.
60
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.
61
Where is the most common location for an orbital meningocele?
Above the medial canthus.
62
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.
63
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.
64
What is the most common bacterial agent likely to lead to orbital cellulitis and CNS infection in infants and young children?
H. influenzae.
65
What is the most common bacterial agent implicated in orbital cellulitis in adults?
Staphylococcus.
66
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.
67
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.
68
What systemic disease may be associated with congenital encephaloceles?
Neurofibromatosis type 1.
69
What structures pass through the inferior orbital fissure?
Pterygopalatine ganglion.
Maxillary nerve.
Pterygoid nerve.
Inferior ophthalmic vein.
70
What structures pass through the optic foramen?
Optic nerve.
Ophthalmic artery.
Sympathetic fibers from the carotid plexus.
71
What is distichiasis?
It is an extra row of lashes present in the orifices of the Meibomian glands.
72
Where do dermoid cysts usually present in the orbit in children?
Anterior upper temporal orbit.
73
What is the most common benign orbital tumor in adults?
Cavernous hemangioma.
74
What are the ocular features of Crouzon’s syndrome?
1. Proptosis with shallow orbits.
2. Blue sclera.
3. Strabismus.
4. Congenital cataract.
5. Optic atrophy.
6. Hypertelorism.
75
Where is the most common location for sebaceous cell carcinoma?
Sebaceous gland carcinoma occurs more commonly in the meibomian glands of the upper eyelid. These can be extremely aggressive both locally and systemically.
76
What bone forms the lacrimal fossa?
Frontal
77
Where does Whitnall’s ligament insert in the orbit?
It inserts 10 mm above Whitnall’s tubercle.
78
What bones form the medial orbital wall?
Ethmoid, lacrimal, sphenoid and maxillary.
79
Which is the strongest wall of the orbit?
Lateral wall, made up by the zygoma and the greater wing of the sphenoid.
80
What is the embryonic origin of the lacrimal gland?
Surface ectoderm.
81
Where is Rosenmüller’s valve located?
Common canaliculus.
82
A 23-year-old burn victim presents with an ectropion of the lower eyelid. What is the most likely etiology for this?
This patient most likely has a cicatricial ectropion due to scarring of the anterior lamella of the eyelid.
83
Describe the course of the infraorbital nerve within the orbit.
The infraorbital nerve, which is a branch of the trigeminal nerve (CN V), travels via the infraorbital canal anteriorly from the infraorbital groove and exits the orbit about 4 mm below the inferior orbital rim.
84
What is a tripod fracture?
It is a fracture of the zygoma away from the face.
85
How do patients with a tripod fracture present?
They have a variably depressed lateral wall and cheek, depending on the degree of zygomatic rotation away from the face.
86
What symptom characteristically occurs in patients with tripod fractures?
Pain with mouth opening or chewing because of impingement of the zygomatic bone on the coronoid process of the mandible.
87
What bone forms the optic foramen and optic canal?
Lesser wing of the sphenoid.
88
What are the causes of entropion after ptosis repair?
Over aggressive excision of tarsus, improper suture placement, improper sling placement.
89
What is the most frequent cause of unilateral proptosis in adults?
Thyroid orbitopathy.
90
What is the most common cause of unilateral proptosis in children?
Orbital cellulitis.
91
What is the best view to obtain when requesting for a plain radiograph of a patient with orbital trauma?
Waters view is the single best method for demonstrating the maxillary sinuses, as well as fractures of the maxilla, inferior rim, floor and zygomatic arches.
92
Why is MRI a poor choice for imaging blowout fractures?
MRI clearly demonstrates soft tissue details of a blowout fracture better than CT, but the absence of a cortical bone signal makes it a poor choice for visualization of fractures.
93
Does an orbital floor fracture usually occur medial or lateral to the infraorbital nerve?
Medial to the infraorbital nerve.
94
What is the best way to distinguish a restrictive motility disorder from a paretic disorder following a blowout fracture?
Forced-duction testing.
95
What is the most common intracranial tumor to spread to the orbit?
Sphenoid wing meningioma.
96
What is the most common type of Le Fort fracture?
Le Fort II.
97
What kinds of ocular complications can result from a Le Fort II fracture?
Orbital emphysema, enophthalmos, optic nerve trauma and motility disturbances.
98
Which of these materials shrinks the most? The least?
Sclera shrinks the most and cartilage the least.
99
If there is a linear scar of the eyelid associated with eyelid retraction what repair option might be considered?
Scar excision with Z-plasty to correct the linear nature of the scar?
100
From which areas should eyelid skin grafts be obtained?
The upper eyelid skin is the thinnest in the body. The best match is from the opposite upper eyelid.
Second choice would be the post-auricular area.
Third choice would be the supraclavicular area or from the inner part of the arm.
101
What extraocular muscles are commonly involved in Graves’ disease?
The inferior recti are most commonly involved, followed by medial recti then the superior recti and lateral recti muscles.
102
What is the correct procedure for correcting a cicatricial entropion?
A horizontal blepharotomy with rotation sutures to rotate the eyelid segment away from the globe
103
What are the purposes of posterior lamellar grafts?
To replace lost posterior lamellar tissue and by doing so correct eyelid retraction or cicatricial entropion doe to inadequate tissue.
104
What is the most common disease causing eyelid retraction?
Thyroid-related orbitopathy.
105
Describe the appearance of the extraocular muscles affected by Graves’ disease with imaging studies.
In the early acute phase, muscle enlargement may be diffuse, and inflammation may extend anteriorly to involve the tendinous insertions. As the disease progresses, muscle enlargement is more confined to the muscle belly, and the tendon assumes a thinner contour.
106
What non-surgical interventions are available for managing post-traumatic or iatrogenic eyelid retraction?
Intralesional steroid injections and massage.
107
When performing a dacryocystorhinostomy, what bony structures are removed during the osteotomy
During the osteotomy, the lacrimal sac fossa and the superior nasal wall of the nasolacrimal duct are removed, which includes the entire lacrimal bone and part of the maxillary bone
108
What is epiblepharon?
It is a horizontal fold of skin and pretarsal muscle that overrides the lid margin, causing a misdirection of the eyelashes toward the globe.
109
What non-surgical interventions are available for managing a chalazion?
Intralesional steroid injections, a tetracycline, hot compresses.
110
How many millimeters does Müller’s muscle normally elevate the upper eyelid?
2 mm.
111
What is the classic triad of Hand-Schüller-Christian disease?
1. Exophthalmos.
2. Lytic lesions of the skull.
3. Diabetes insipidus.
112
Of the different manifestations of histiocytosis X (Langerhans cell histiocytosis), which one has the worst prognosis and which has the best?
Letterer-Siwe disease results in systemic spread of abnormally proliferating histiocytes with rapid death; while eosinophilic granuloma, where disease is confined to isolated bony lesions, has the best prognosis.
113
A 54-year-old golfer presents with a 6mm necrotizing lesion of the eyelid. What is the most likely diagnosis?
Basal cell carcinoma although other forms of skin cancer cannot be excluded.
114
What does the grey line in the eyelid represent and what is its significance?
This represents the most posterior pretarsal orbicularis muscle fibers (muscle of Riolan). A vertical incision made here will split the eyelid into anterior (skin and orbicularis) and posterior (conjunctiva and tarsus) layers.
115
What are the signs of orbital apex syndrome?
1. Decreased visual acuity.
2. External and internal ophthalmoplegia.
3. Decreased sensation.
116
What is the horizontal length of the eyelid?
About 29 or 30 mm.
117
What is the vertical height of the upper eyelid tarsus and the lower eyelid tarsus?
10 mm and slightly less than 4 mm, respectively.
118
What would be diagnostic for orbital mucormycosis in biopsy specimens?
The presence of large, nonseptate branching hyphae in biopsy specimens of the orbit is pathognomonic for orbital mucormycosis. There is ischemic necrosis due to arteriolar invasion.
119
How does orbital mucormycosis spread to the intracranial cavity?
Via the ophthalmic artery.
120
Why is the treatment of pleomorphic adenomas or benign mixed tumor of the lacrimal gland complete excision without incisional biopsy?
Why is the treatment of pleomorphic adenomas or benign mixed tumor of the lacrimal gland complete excision without incisional biopsy?
121
What is the cause of congenital dacryoceles, and what is the treatment?
Congenital dacryoceles are due to an obstruction of the nasolacrimal duct with amniotic fluid or mucus filling the dilated lacrimal sac. Probing performed during the first year of life results in a cure rate of greater than 90%.
122
What are the most common clinical features of carotid-cavernous fistula?
Proptosis, chemosis, bruit, ocular motor nerve palsies, increased IOP and retinopathy.
123
What re the most common causes of painful external ophthalmoplegia?
Thyroid disease, TB, sarcoidosis, Wegener’s granulomatosis, metastatic breast, prostate or GI cancer, Tolosa-Hunt syndrome, diabetes mellitus, cavernous sinus thrombosis and mucormycosis.
124
What is the most common orbital tumor in childhood?
Capillary hemangioma, which is absent at birth, appears by one year of age, increases in size and disappears by age 5 years. It can produce occlusion or meridional amblyopia.
125
What is the most common orbital tumor in adults?
Cavernous hemangioma.
126
What is the treatment of choice for cavernous hemangiomas?
Surgical excision.
127
What does orbital CT scanning of an optic nerve glioma show?
Fusiform enlargement of the optic nerve.
128
What is the incidence of neurofibromatosis in a child with an optic nerve glioma?
25 to 50%.
129
How long do adult patients with optic nerve gliomas live after being diagnosed with the tumor?
Most of these patients die within 6-12 months. This tumor is benign in children, although it can involve the more posterior structures such as the optic chiasm and sella turcica.
130
What can be expressed from canaliculi infected with Actinomyces?
Yellow sulfur granules.
131
What is the normal position of the eyebrow in a male and in a female?
In men, the eyebrow is usually at or just below the superior orbital rim, while in women it is above the superior orbital rim.
132
What is a reliable sign of penetration of the orbital septum during eyelid surgery or evaluation of eyelid trauma?
Presence of fat in the surgical field.
133
What bones form the orbital floor?
Maxillary, zygomatic and palatine bones.
134
What muscle separates the medial from the central fat compartment in the lower eyelid?
The inferior oblique muscle.
135
What is the most common cause of congenital obstruction of the nasolacrimal duct?
Membranous blockage at the valve of Hasner.
136
What is hypertelorism?
Increased distance between the medial orbital walls.
137
What is telecanthus?
Increased distance between the medial canthi of the eyelids as a result of abnormally long medial canthi tendons.
138
What is Horner’s syndrome?
It is produced by interruption in sympathetic innervation to the eye and is characterized by miosis, mild ptosis, anhidrosis, and enophthalmos.
139
What is the Fasanella-Servat procedure?
It is a transconjunctival resection of the upper border of the tarsus together with the lower border of Müller’s muscle used to correct mild ptosis due to Horner’s syndrome and very mild congenital ptosis.
140
How do you perform the Jones 1 test, and how do you interpret its results?
The Jones 1 test differentiates a partial obstruction of the lacrimal passages from hypersecretion of tears.
Fluorescein is instilled into the conjunctival sac. After 5 minutes, a cotton-tip bud moistened in 4% cocaine is inserted under the inferior turbinate at the opening of the nasolacrimal duct.
Fluorescein recovered from the nose indicates that the drainage system is patent, and the test is considered positive.
If no dye is recovered, there is either a partial obstruction somewhere along the lacrimal drainage passages or failure of the lacrimal pump mechanism. The Jones 2 test is then performed.
141
How do you do the Jones 2 test, and how do you interpret the results?
This test identifies the probable site of partial obstruction after a negative Jones 1 test.
Topical anesthetic is instilled into the conjunctival sac and any residual fluorescein is washed out. The drainage system is then irrigated with saline.
If fluorescein-stained saline is recovered from the nose, there is a partial obstruction to the nasolacrimal duct; and the test is considered positive.
If no fluorescein is recovered, the obstruction lies in the upper drainage system (punctum, canaliculi or common canaliculus) or there is a defective lacrimal pump mechanism.
142
What are the lengths of the various parts of the lacrimal drainage system in adults?
1. Ampulla (2 mm).
2. Canaliculus (8 mm).
3. Nasolacrimal sac (10 mm).
4. Nasolacrimal duct (12 mm).
143
What is the treatment for acute dacryocystitis?
Broad-spectrum systemic Ab and warm compresses. Irrigation and probing is contraindicated. A dacryocystorhinostomy may be necessary once the infection has been controlled.
144
When is insertion of a Jones tube indicated during a DCR?
A Jones tube is inserted when there is absence of canalicular function.
145
When should probing be performed in a child with congenital nasolacrimal duct obstruction?
Probing is not done until the child is 12-18 months old because spontaneous recanalization occurs in about 95% of cases.
146
What is the cure rate of congenital nasolacrimal duct obstruction with probing?
90% are cured after the first probing, and an additional 6% by the second probing.
147
If probing fails to cure the nasolacrimal duct obstruction, when should a DCR be performed?
Patients who fail two technically satisfactory probings and insertion of silastic tubes or balloon dilation of the nasolacrimal duct can be treated by DCR between the ages of 3 and 4 years.
148
What condition is epicanthus inversus associated with?
Blepharophimosis syndrome.
149
When do you suspect that lid retraction is present?
Lid retraction is suspected when the upper lid margin is level with or above the superior limbus of the eye.
150
What are the attachments of the medial canthal tendon?
The superficial head of the pre-tarsal and pre-septal portions of the orbicularis muscle tendon insert onto the anterior lacrimal crest while the deep heads of the tendons insert into the posterior lacrimal crest. The orbital portion of the orbicularis muscle inserts into the anterior lacrimal crest. The lacrimal sac is invested between the deep and superficial head of the tendon.
151
How would you treat a patient with blepharophimosis syndrome?
Correction of the epicanthus and telecanthus followed a few months later by bilateral frontalis suspension for the ptosis.
152
What are the attachments of the lateral canthal tendon?
The lateral canthal tendon is in fact a raphe or interdigitation of muscle fibers. It is attached to the lateral orbital tubercle on the inner surface of the lateral orbital wall, slightly posterior to the lateral orbital rim.
153
What is the margin-reflex distance (MRD), and what is the normal value?
It is the distance between the upper lid margin and the light reflex of the pupil with the patient looking directly at a penlight held by the examiner. The normal MRD is about 4 mm.
154
How often is the eye involved in myasthenia gravis, and what are the eye manifestations?
The eye is involved in 90% of cases and is the presenting feature in 60%. Ocular manifestations include ptosis, diplopia, and nystagmoid movements on extremes of gaze.
155
What tests can you do to evaluate a patient for myasthenia gravis?
Tensilon (edrophonium) test.
Electromyography.
Presence of antibodies to acetylcholine receptors.
CT or MRI of the anterior mediastinum to rule out a thymoma.
156
Does a negative Tensilon test result eliminate the possibility of myasthenia gravis?
NO
157
How often are antibodies to acetylcholine receptors present in patients with myasthenia gravis?
90% of cases
158
How much of an eyelid can be removed via a wedge resection allowing the resulting defect to be closed primarily?
About one-fourth to one-third of the eyelid, depending upon the amount of eyelid laxity that is present. In some older individuals as much as 40 percent of an eyelid can be removed and the defect closed primarily.
159
If slightly extra eyelid tissue is needed to close a defect what is the simplest option?
A canthotomy and cantholysis of the eyelid tendon with allow closure of a defect involving as much as 50 percent or more of an eyelid.
160
When is a Tenzel flap used to close eyelid defects?
A Tenzel semicircular flap is used to close defects involving more than a third but less than half of the eyelid.
161
What is the Hughes procedure?
This is a procedure used to correct lower eyelid defects greater than 50% that involves taking a tarsoconjunctival flap from the upper eyelid, leaving behind 3 to 4 mm of the upper tarsus intact, and advancing the flap to correct a lower eyelid defect.
162
How do you define hyperkeratosis?
Hyperkeratosis is a thickening of the stratum corneum or keratin layer, usually by too rapid growth and maturation of the epidermis.
163
What is acanthosis?
Thickening of the squamous cell layer.
164
What is dyskeratosis?
Occurrence of keratin in the basal cell layer or deeper layers of the prickle cell layer.
165
What is the treatment for the nevus flammeus of Sturge-Weber syndrome?
Yellow dye laser (wavelength 577 or 585 nanometers).
166
What are the ocular side effects of botulinum toxin therapy for essential blepharospasm?
Ptosis, strabismus, lagophthalmos, and ectropion or entropion depending on tone of the eyelids prior to injection.
167
What radiologic and clinical findings would suggest a malignancy of the lacrimal gland?
Bone destruction, pain, calcification of the mass and irregular borders of the mass are all suggestive of a malignant process.
168
When excising a basal cell carcinoma, how much normal tissue around the lesion should be removed?
At least a 3 mm area of normal appearing tissue should be removed as well as the obvious tumor.
169
How often does neuroblastoma metastasize to the orbit?
40% of cases, which typically presents with abrupt onset of proptosis accompanied by lid ecchymosis.
170
What are the ocular features of Crouzon’s syndrome?
V ery shallow orbits with proptosis. Optic atrophy.
Blue sclera.
Strabismus.
Congenital cataract.
171
What are two methods for correcting epicanthal folds?
Either an Y to V plasty or Mustard’s double opposing Z-plasty.
