504 Emergency Medicine
examination in the ED, patients with orbital blowout fractures should be
referred to an ophthalmologist for a repeat examination to rule out a trau-
matic retinal detachment. Ruptured globes (b)are more common with
penetrating trauma and clues to this diagnosis are shallow anterior cham-
ber, hyphema, irregular pupil, significant decrease in vision. If a ruptured
globe is suspected, a hard eye shield should be applied and ophthalmology
consulted. Do not check IOP in patients with suspected ruptured globes as
this can worsen the injury. Cranial nerve III palsy (d)presents with prob-
lems with medial gaze, upward gaze, downward gaze as well as ptosis. This
patient only has difficulty with upward gaze suggesting that cranial nerve III
is intact. Traumatic retrobulbar hemorrhage (e)is a displacement of the globe
and septum anteriorly caused by bleeding into the orbit. Since the globe has
limited capacity for expansion, continued bleeding puts pressure on ocular
structures. Optic nerve compression leads to decreased visual acuity and con-
tinued globe pressure leads to proptosis. Patients with a traumatic history and
clinical signs suggestive of retrobulbar hemorrhage require emergency orbital
decompression via lateral cantholysis.
458.The answer is c.(Knoop et al, p 67. Tintinalli, pp 1451, 1463.)This
patient has an afferent pupillary defect (APD),also known as a Marcus
Gunn pupil.In patients with an APD, light shined into the affected pupil
causes a small dilation with no constriction. APD is a result of a lesion in
the anterior visual pathway of the retina, optic nerve, or optic chiasm pre-
venting reception of the light in the affected eye. Neither pupil constricts
since constriction is centrally mediated in the midbrain. APDs are sensitive
for disease, but not specific. The differential diagnosis for an APD includes
central retinal artery or vein occlusion, optic nerve disorders, such as optic
neuritis, tumor or glaucoma, and lesions in the optic chiasm or tract.
Anisocoria(a)is unequal pupil size. Under normal room lighting, nor-
mal pupils may be 1 to 2 mm different in size. An Argyll Robertson pupil (b)
constricts during accommodation (as expected), but does not constrict in
response to light. This is usually seen in both eyes and is associated with neu-
rosyphilis. Horner syndrome (d)is decreased sympathetic innervation of the
eye from interruption of the sympathetic chain at any point from the brain-
stem to the sympathetic plexus around the carotid artery. Clinically, patients
with Horner syndrome have ptosis, miosis, and anhydrosis. (e)Normal
pupil response to light is pupil constriction followed by a small amount of
dilatation.