Ptosis

What Is Ptosis

Ptosis (pronounced TOE-sis) is an abnormally low position of the upper eyelid. When the levator muscle — the primary eyelid elevator — or Müller’s muscle weakens, stretches, or detaches from the eyelid, the lid drops in front of the pupil. Ptosis may affect one eye or both and ranges from barely noticeable to severe enough to obstruct vision entirely.

• Ptosis is also called blepharoptosis
• It differs from dermatochalasis (excess upper eyelid skin) — though both conditions frequently coexist
• A drooping lid that crosses the pupil reduces the superior visual field, causes eyebrow strain and headaches, and in children can lead to amblyopia (“lazy eye”)

Types & Causes of Ptosis

Ptosis is grouped by cause — age-related (aponeurotic), congenital, and neurologic. Recognizing the type guides both the work-up and the operation.

Acquired Ptosis

Most adult ptosis is aponeurotic — the levator muscle is intact and still strong, but the fibrous aponeurosis (tendon) that transmits the muscle’s pull to the tarsus has stretched, thinned, or detached. The lid sits low not because of muscle weakness but because the mechanical connection is lost.

Common Causes

• Aging: the most common cause by far — the aponeurosis disinserts from the tarsus gradually over decades. Levator function typically remains excellent (≥ 10 mm)
• Long-term contact lens wear: repeated mechanical trauma from lens insertion and removal stretches the aponeurosis; a common cause in younger adults
• Prior intraocular surgery: lid speculum use during cataract surgery is a well-recognized precipitant
• Chronic eye rubbing or inflammation: repeated lid traction weakens the aponeurosis over time
• Myasthenia gravis: a neuromuscular disorder producing variable, fatigable ptosis that characteristically worsens as the day progresses — must be excluded before planning surgery
• Third nerve (CN III) palsy: causes complete ptosis with a dilated, unreactive pupil; the pupil-involving form is a neurological emergency requiring urgent imaging

Congenital Ptosis

Congenital ptosis results from a developmental dystrophy of the levator muscle itself — fibrosis replaces normal striated muscle fibers, leaving the muscle stiff and underpowered. Unlike aponeurotic ptosis, the levator function is poor from birth.

Clinical Features

• Ptosis ranges from mild (lid partially covers pupil) to severe (pupil completely occluded)
• Lid lag on downgaze is characteristic: because the fibrotic muscle cannot fully relax, the lid stays high when looking down — the opposite of acquired ptosis
• Associated findings: amblyopia in up to 20% of cases, strabismus in ≈ 31%, and astigmatism
• Children may tilt the head back into a “chin-up” posture to see under the drooping lid

When to Operate

Surgery is deferred until age 3–5 (“pre-school years”) when possible, so intraoperative cooperation is better and the child has had time for amblyopia treatment. However, when the lid occludes the visual axis and threatens vision development, correction must be performed earlier — even in infancy.

Horner’s Syndrome

Horner’s syndrome is caused by interruption of the sympathetic nerve pathway supplying the eye. Because sympathetic fibers innervate Müller’s muscle (the secondary upper lid elevator) and the inferior tarsal muscle, their loss produces a mild but distinctive ptosis of 1–2 mm.

Classic Triad

• Ptosis (upper lid, 1–2 mm) — Müller’s muscle denervation
• Inverse ptosis / lower lid elevation — inferior tarsal muscle denervation
• Miosis (small pupil) with dilation lag in dim light

Localizing the Lesion

The three-neuron sympathetic pathway is disrupted at different levels depending on the cause:

• First-order (central): hypothalamus to spinal cord — stroke, tumor, demyelination, syringomyelia
• Second-order (preganglionic): spinal cord to superior cervical ganglion — Pancoast tumor of the lung apex, carotid or subclavian artery pathology, cervical rib
• Third-order (postganglionic): superior cervical ganglion to orbit — carotid artery dissection, cavernous sinus mass, cluster headache

New-onset Horner’s syndrome requires urgent MRI/MRA to rule out carotid dissection or intracranial mass. In infants and children, Horner’s syndrome can cause heterochromia (lighter iris on the affected side) because sympathetic tone is needed for normal melanin development in the iris stroma.

Marcus Gunn Jaw Wink

Marcus Gunn jaw-wink ptosis is an example of synkinesis — an abnormal neural connection between two muscle groups that are normally unrelated. A branch of the trigeminal nerve (CN V, which supplies the pterygoid jaw muscles) misdirects into the branch of the oculomotor nerve (CN III) that lifts the upper eyelid. The result: the ptotic lid rises whenever the jaw opens or moves laterally.

Use the slider in the animation above to simulate the jaw-wink synkinesis — the eyelid rising as the jaw opens.

Key Features

• Occurs in 2–13% of patients with congenital ptosis
• Levator function is typically poor (≤ 4 mm)
• Does not improve spontaneously, though children learn to minimize visible jaw movement over time
• Associated strabismus in ≈ 60%, amblyopia in ≈ 35%

Treatment

The surgical approach is guided by the severity of both the ptosis and the jaw-wink:

• Mild jaw-wink with significant ptosis: unilateral frontalis sling may achieve acceptable symmetry
• Significant jaw-wink: bilateral levator muscle disinsertion followed by bilateral frontalis sling — this eliminates the synkinesis entirely and allows symmetrical correction

Explore Ptosis

From diagnosis to the right operation, explore each part of ptosis care in depth: