Marcus Gunn Phenomenon: Causes, Symptoms, and Treatment
Medically reviewed by Harsha Moole, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Marcus Gunn Phenomenon?
An ophthalmologist, an eye doctor, usually diagnoses and treats Marcus Gunn Phenomenon. Because it often shows up in babies, a pediatric ophthalmologist, an eye doctor for children, is a common choice. If surgery is needed, an eye surgeon will do it. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is Marcus Gunn phenomenon?
Marcus Gunn phenomenon is a rare condition that is usually present from birth. One upper eyelid moves when the jaw moves. This often looks like an involuntary wink, or a lift of the eyelid, when a person chews, sucks, or moves the jaw in certain ways. Parents may first notice it when their baby is feeding.
It usually affects just one eye. In rare cases, both eyes are involved. It affects males and females equally.
Symptoms
The main sign is a droopy upper eyelid that lifts when the jaw moves. Common signs include:
- A mild to moderate droop of one upper eyelid, called ptosis.
- The eyelid lifts when the mouth opens, the jaw moves to the opposite side, or the person chews, sucks, pushes the jaw forward, clenches the teeth, or swallows.
- The wink gets worse when the person looks down.
Marcus Gunn phenomenon is sometimes linked to other eye problems. Strabismus, which means the eyes do not line up, occurs in about 50-60% of cases. Amblyopia, also called lazy eye, can also occur. It usually comes from crossed eyes or different vision between the eyes, and rarely from the droopy eyelid blocking vision.
Causes and who gets it
The muscle that lifts the upper eyelid is controlled by one nerve. The jaw muscles are controlled by a branch of a different nerve, the trigeminal nerve. In Marcus Gunn phenomenon, these nerves are miswired. Moving the jaw also moves the eyelid. Doctors call this synkinesis, which means movement that happens together.
It is not known why the miswiring happens. It likely happens early in the baby's development before birth. Most cases occur without a known genetic cause. Cases that run in families are very rare. Sometimes it is part of a syndrome, such as CHARGE syndrome, a condition with several birth defects.
How doctors diagnose it
Doctors diagnose Marcus Gunn phenomenon by watching the eyelid move when the jaw moves. They also check for related problems, such as lazy eye and misaligned eyes. A full eye exam usually includes:
- Vision testing to check for lazy eye.
- A pupil check to see how the eyes react to light.
- Eye movement tests to look for misaligned eyes or weak eye muscles.
- Eyelid tests to measure how much the eyelid moves and how severe the droop is.
Treatment
Many people with Marcus Gunn phenomenon do not need treatment. Treatment can be considered if the droopy eyelid is severe, causes vision problems, or is a cosmetic concern.
Lazy eye is treated first if it is present. This may involve patching the stronger eye to make the weaker eye work harder. It may also involve glasses or contact lenses to correct vision differences between the eyes.
Surgery is considered if the droop is severe, interferes with vision, or if the jaw-winking is very noticeable. Doctors usually wait until the child is at least 1 to 2 years old because anesthesia is safer after infancy. Surgeons may tighten the lifting muscle or connect the eyelid to the forehead muscle so the forehead helps lift it. If the wink is too severe, surgeons may disable or remove the lifting muscle to stop the abnormal movement.
Like any surgery, eyelid surgery has risks. The eyelid may still droop or be lifted too high. The eye may not close fully, which can lead to dryness. A small lump of tissue may form around the stitches.
When to see a doctor
See an eye doctor if your baby's eyelid moves with chewing or sucking. Early checks matter because lazy eye can develop, usually from misaligned eyes and rarely from a droopy eyelid that blocks vision. Close follow-up is essential to make sure a child's vision develops properly.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. Such a doctor can notice the eyelid movement, refer you to an eye specialist, and help coordinate follow-up visits.
Common questions
Is Marcus Gunn phenomenon dangerous?
Usually not. Most people with Marcus Gunn phenomenon have a good outlook. The main concern is lazy eye, which can be treated successfully with careful monitoring and treatment.
Does Marcus Gunn phenomenon need surgery?
No, many people with Marcus Gunn phenomenon do not need treatment. Surgery is considered if the eyelid droop is severe, interferes with vision, or if the jaw-winking is very noticeable.
Can Marcus Gunn phenomenon run in families?
Rarely. Cases that run in families have been described, but they are very rare. Most cases occur without a known genetic cause.
Does Marcus Gunn phenomenon affect both eyes?
Usually not. It usually affects just one eye, but in rare cases both eyes are involved.
Sources
- National Organization for Rare Disorders (NORD) - Marcus Gunn Phenomenon
- American Academy of Ophthalmology - EyeWiki: Marcus-Gunn Jaw Winking Ptosis
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
