A to Z: Marcus Gunn Syndrome

May also be called: Marcus Gunn Phenomenon; Marcus Gunn Jaw-Winking Syndrome; Jaw Winking; Jaw-Winking Syndrome

Marcus Gunn syndrome is a congenital condition where a drooping eyelid briefly opens wider and appears to wink when the jaw is moved. (A congenital condition means a baby is born with it.)

More to Know

Many children are born with a condition called ptosis, or drooping of the upper eyelid. Ptosis usually doesn’t interfere with a child’s vision, but it can make one eyelid lower than normal. Marcus Gunn syndrome causes the eyelid to briefly open wider when the jaw is moved in a certain way. This “jaw winking” can happen when a child opens his or her mouth, thrusts the jaw to the side opposite the affected eye, sticks the jaw out, chews, smiles, or sucks. When the jaw is moved back to its normal position, the eyelid returns to place.

Marcus Gunn syndrome, named for the doctor who described the condition in 1883, is usually only found in one eye. But in rare cases, both eyes may be affected. Treatment for Marcus Gunn syndrome is not always needed, as it causes no complications and tends to get less noticeable with age. In some cases, however, Marcus Gunn syndrome can be associated with other eye and vision problems that can benefit from occlusion therapy (using an eye patch to strengthen a “lazy” eye), glasses, or surgery.

Keep in Mind

Marcus Gunn syndrome doesn’t cause any symptoms other than jaw winking, and it usually becomes less noticeable as a child ages. Treatment is only necessary if there is an eye or vision problem, although some people choose to have the condition corrected for cosmetic reasons. Treatment for Marcus Gunn syndrome usually corrects the condition with no long-term problems.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.