Orbits Flashcards
Treatment for Traumatic Hyphema
a) topical cycloplegics
b) carbonic anyhdrase inhibitors
c) beta blockers
d) Versed
e) A and B
Topical cycloplegics and carbonic anhydrase inhibitors to decrease intraocular pressure.
Long-term consequences of hyphema leading to blindness
Corneal staining and glaucoma
Cycloplegic drugs have what mechanism of action? Pleas provide examples of this class of drug
Cycloplegic drugs are generally muscarinic receptor blockers. These include atropine, cyclopentolate, homatropine, scopolamine and tropicamide
Distance from anterior lacrimal crest to…
Anterior ethmoidal foramen
Posterior ethmoidal foramen
Optic Canal
to anterior ethmoid foramen 24mm
to posterior ethmoidal foramen 36mm
to optic canal 42mm
Telecanthus is different from hypertelorism in that there is only an increase in once of the following
a) Outer canal distance
b) Inner canthal distance
c) Interpupillary distance
B) Inner Canthal distance is increased in telecanthus.
In Hypertelorism, the OCD, ICD, and IPD are all increased
Telecanthus is associated with syndromes such as
Down syndrome, FAS, Cri du Chat, Klinefelter, Turner, adnd Ehlers Danlos
Hypertelorism is not typically associated with syndromes, but rather with
Craniofacial clefts, craniofacial dysplasia, and craniosynostoses syndromes
Which of these is true lateralization of the orbit?
Telecanthus or Hypertelorism
Hypertelorism
A medial canthopexy is the treatment for
a) telecanthus
b) hypertelorism
Telecanthus, as this only involves inner canthal distance increase
Patient’s with a previous history of orbital floor reconstruction are at a (higher or lower) risk for globe rupture because the orbital floor is (more or less) likely to fracture
Patient’s with a previous history of orbital floor reconstruction are at a higher risk for globe rupture because the orbital floor is less likely to fracture
Consensual light reflex test is the best method for diagnosis of what?
Relative afferent pupillary defect, or Marcus-Gunn pupil.
Illumination of one eye that results in failure to constrict pupils of both eyes is suggestive of a RAPD
What is the instrument used to measure intra-ocular pressure?
A tonometer measures intra-ocular pressure
An extremely lower reading on a tonometer could suggest…
An extremely low reading on a tonometer could suggest a glob rupture
Normal tonometer range
11-20mm Hg is a normal IOP
An elevated tonometer reading could suggest…
An elevated IOP could suggest a retrobulbar hematoma
The red color saturation test is a measure of what?
The red color saturation test is the best measure of optic nerve function.
A red object is held in front of each eye separately and the patient is asked whether the object has the same hue (color) and intensity (brightness) in each eye.
Monocular diplopia is the anatomical result of…
Monocular diplopia is the result of retinal detachment or lens dislocation
Binocular diplopia is commonly seen secondary to…
Edema, neuromuscular paralysis, or extraocular muscle entrapment
The Hertel exophthalmeter utilizes what region of the face to measure globe position based on the surrounding bone
The Hertel exophthalmeter utilizes the zygomaticofrontal region
The Naugel exophthalmeter utilizes what region of the face to measure globe position based on the surrounding bone
The naugel exophthalmeter utilizes the frontal bone
Absolute indications for surgical repair of an orbital floor fracture
- Globe malposition with enophthalmos
- Muscle entrapement with resulting diplopia
- Obital floor “trap door” fracture that has elicited the occulocardiac reflex
Contraindications for surgical repair of an orbital floor fracture
- Any condition that puts the globe at injury (hyphema, retinal tears, lens displacement)
- The status of the noni-njured eye. What if the patient is blind in one eye or only has one eye?
Grading of hyphema
Vertical filling of anterior chamber of the eye Grading system Grade I: <1/3 Grade II: 1/3 - 1/2 Grade III: 1/2 to near total Grade IV: Total filling
What is the nickname for Grade IV hyphema
Eight ball (the anterior chamber of the eye is completely filled with blood
Clinical findings associated with superior orbital fissure syndrome
- Loss of forehead sensation
- Loss of corneal reflex
- Ophthalmoplegia
- Upper lid ptosis
- Edema (secondary to venous obstruction)
- Proptosis
What is the difference between superior orbital fissure syndrome and orbital apex syndrome?
Orbital apex syndrome involves the optic nerve, causing loss of vision. So, orbital apex syndrome has the same findings of superior orbital fissure syndrome, plus loss of vision.
- Loss of forehead sensation
- Loss of corneal reflex
- Ophthalmoplegia
- Upper lid ptosis
- Edema (secondary to venous obstruction)
- Proptosis
Average orbital volume
Slightly less than 30ml
Average globe volume
7ml
What level of enophthalmos can be expected with a 1cm3 increase in orbital volume?
3-4mm
What are the two types of ophthalmoplegia?
Chronic progress external and internal ophthalmoplegia
Chronic progressive external ophthalmoplegia (CPEO), is a type of eye disorder characterized by slowly progressive inability to move the eyes and eyebrows. It is often the only feature of mitochondrial disease, in which case the term CPEO may be given as the diagnosis.
Internal is impairment of horizontal eye movements caused by damage to certain connections between nerve centers in the brain stem
Define ophthalmoplegia
Paralysis or weakness of the eye muscles
What nerve provides motor function to the inferior rectus muscle?
The oculomotor nerve
What nerve provides motor functions to the lateral rectus muscle?
The abducens nerve (CN VI)
What nerve provides motor function to the superior oblique muscle?
The trochlear nerve (CN IV)
What is the Gray Line?
The gray line is the pretarsal orbicularis oculi muscle on the eyelid margin. When placing a Frost suture, the suture is passed through the gray line
What is another name for the Gray line
The muscle of Riolan
What is a meibomian gland?
Meibomian glands are the tiny oil glands which line the margin of the eyelids (the edges which touch when the eyelids are closed). These glands secrete oil which coats the surface of our eyes and keeps the water component of our tears from evaporating (drying out)
