■ To be discharged, patients should be alert and oriented (or returned to age-
appropriate baseline), vital signs should be stable and patient should be
escorted by a reliable adult who will observe them after discharge. Absent
lower extremity injuries, patients who walk in should walk out.
OPHTHALMOLOGIC PROCEDURESLateral Canthotomy
INDICATIONS
■ Retrobulbar hemorrhage resulting in acute loss of visual acuity, increased
IOP, and proptosis
■ An IOP >40 mm Hg (normal IOP is 10–21 mm Hg)
■ In patients with retrobulbar hemorrhage with afferent pupillary defect,
ophthalmoplegia, cherry-red macula, optic nerve head pallor, or severe
eye pain
CONTRAINDICATIONS
■ Suspected globe rupture: Hyphema, irregular pupil, exposed uveal tissue,
and/or limited extraocular movements
■ Tonometry and globe palpation are also contraindicated in patients with
an open globe injury.
TECHNIQUE
■ Use local anesthesia and conscious sedation with or without paralysis so
that patient doesn’t move during procedure.
■ Clear debris with NS
■ Crimp skin at the lateral corner of patient’s eye with hemostat, pick up
skin of lateral orbit and use scissors to make a 1- to 2-cm incision from lat-
eral corner of the eye and extending laterally.
■ Visualize lateral canthus tendon by pulling down on inferior lid and with
scissors pointing away from the globe, dissect the inferior lateral canthus
tendon and cut it.
■ If IOP remains elevated (>40 mm Hg), cut the superior portion of the lat-
eral tendon.
COMPLICATIONS
■ Iatrogenic globe injury, bleeding, and infection
■ Irreversible vision loss can occur if retina ischemia time is >90–120 minutes.
INTERPRETATION OFRESULTS
■ The afferent pupillary defect, or Marcus Gunn pupil, is tested using the
swinging flashlight test. The test is positive when the affected pupil dilates
in response to light (the other normal pupil also dilates when light is
shone in the affected eye). Both pupils constrict when the light is shone in
the normal eye. The Marcus Gunn pupil results from injury to the affer-
ent fibers of cranial nerve II of the defective eye, while the efferent signals
from cranial nerve III to both eyes are uninjured.
■ A successful procedure is marked by improved visual acuity, resolution of
a previously detected afferent pupillary defect, and decrease in IOP to
below 40 mm Hg.
PROCEDURES AND SKILLSCauses of an afferent
pupillary defect: Glaucoma,
retrobulbar hematoma, retinal
pathology, optic neuritis/MS