Afferent Pupillary Defect

Marcus Gunn pupil (relative afferent pupillary defect)

is a medical sign observed during the swinging-flashlight test^[1] whereupon the patient's pupils constrict less (therefore appearing to dilate) when a bright light is swung from the unaffected eye to the affected eye.

The affected eye still senses the light and produces pupillary sphincter constriction to some degree, albeit reduced.

The most common cause of Marcus Gunn pupil is a lesion of the optic nerve (proximal to the optic chiasm) or severe retinal disease. It is named after Scottish ophthalmologist Robert Marcus Gunn.^[2]


  Look for an afferent pupillary defect (RAPD - also known as Marcus Gunn Pupil) by:

a.       The Swinging Flash Light Test

b.      The pupils must react to light in order to perform the test

c.       Not a test of the pupil per se—but we do the test when we look at the pupil

d.      Tests the optic nerve function

e.       Relies on a difference between the two optic nerves—one must be different from each other

 

 

Subperiosteal Abscess

Bilateral ethmoidal sinusitis with subperiosteal abscess of the left medial wall.

amaurosis fugax

Amaurosis fugax (Latin fugax meaning fleeting, Greek amaurosis meaning darkening, dark, or obscure) is a transient monocular visual loss.

The experience of amaurosis fugax is classically described as a transient monocular vision loss that appears as a "curtain coming down vertically into the field of vision in one eye;" however, this altitudinal visual loss is relatively uncommon. In one study, only 23.8 percent of patients with transient monocular vision loss experienced the classic "curtain" or "shade" descending over their vision.^[43]

Other descriptions of this experience include a monocular blindness, dimming, fogging, or blurring.^[44] Total or sectorial vision loss typically lasts only a few seconds, but may last minutes or even hours. Duration depends on the etiology of the vision loss. Obscured vision due to papilledema may last only seconds, while a severely atherosclerotic carotid artery may be associated with a duration of one to ten minutes.^[45] Certainly, additional symptoms may be present with the amaurosis fugax, and those findings will depend on the etiology of the transient monocular vision loss.

MANY CAUSES OF AMAUROSIS FUGAX

Cell and Flare

Cell and Flare

Physical exam finding often associated with acute iritis