Blepharoptosis is the medical term for an abnormally low-lying upper eyelid when the eye is in a primary, straight-ahead gaze. The condition can affect one or both eyes and varies in severity. For some, the droop is a subtle cosmetic concern, while for others, the eyelid descends far enough to obstruct vision. It can affect individuals of any age.
Causes and Classifications of Blepharoptosis
The origins of blepharoptosis are categorized by the age of onset: congenital, present at birth or within the first year, and acquired, which develops later. Congenital ptosis is most often myogenic, resulting from improper development of the levator palpebrae superioris muscle, the primary muscle for lifting the eyelid. In these cases, muscle fibers are often replaced by fibrous tissue, which diminishes the muscle’s ability to contract properly.
Acquired ptosis, the more common form, is classified by its cause. The most frequent type is aponeurotic ptosis, resulting from the stretching or detachment of the levator aponeurosis—the tendon connecting the levator muscle to the eyelid. This is often an age-related change but can be accelerated by long-term hard contact lens wear, frequent eye rubbing, or as a complication of eye surgery like cataract removal.
Neurogenic ptosis arises from problems with the nerve signals controlling eyelid muscles. This can be due to conditions affecting the third cranial nerve, which innervates the levator muscle, or issues with sympathetic nerves supplying the smaller Müller’s muscle. Specific causes include third nerve palsy, Horner’s syndrome, and multiple sclerosis.
Myogenic ptosis in adults stems from a muscle disorder that weakens the levator muscle. Myasthenia gravis, a condition affecting the neuromuscular junction, is a well-known cause and often presents with ptosis that worsens with fatigue. Mechanical ptosis occurs when the eyelid is weighed down by a mass like a cyst or tumor. Traumatic ptosis is the direct result of an injury that damages the muscle, its aponeurosis, or the controlling nerves.
Associated Symptoms and Potential Complications
The most direct symptom is the visible drooping of the eyelid, creating an asymmetrical or tired appearance. A primary complaint is a blockage of the upper field of vision, interfering with activities like reading or driving. To compensate, individuals may raise their eyebrows to lift the lids, which can lead to forehead strain and headaches. Another common posture is tilting the head backward into a “chin-up” position to see underneath the drooping lid.
These effects can lead to eye strain and a feeling of eyelid heaviness, particularly late in the day. The complications of ptosis differ between children and adults. For adults, the main concerns are the functional vision loss and cosmetic appearance, and the constant effort to see can cause discomfort.
In children with congenital ptosis, the risks are developmental. If a drooping eyelid covers the pupil, it can lead to amblyopia (lazy eye). Amblyopia occurs because the brain doesn’t receive clear images from the affected eye, preventing normal development of visual pathways. The pressure of the drooping lid on the cornea can also induce astigmatism, further contributing to this risk.
The Diagnostic Process
Diagnosing blepharoptosis involves a clinical examination to determine the cause and severity. An ophthalmologist will review the patient’s history, noting the onset and variability of symptoms. The physical assessment includes specific measurements, like the marginal reflex distance 1 (MRD1). This is the distance in millimeters from a penlight’s reflection on the cornea to the upper eyelid’s edge; a normal MRD1 is 4 to 5 mm.
To assess muscle strength, a levator function test is performed. This measures the distance the eyelid travels from extreme downgaze to upgaze while the examiner holds the patient’s brow to prevent assistance from forehead muscles. A function greater than 10 mm is excellent, while 5 mm or less is poor.
Visual field testing may be conducted to understand the functional impact. This test maps the superior visual field with the eyelid in its natural position and again with the lid manually lifted. The difference demonstrates how much peripheral vision is obstructed. If a neurogenic or myogenic cause is suspected, blood tests or imaging studies may be ordered to identify an underlying disease.
Treatment Approaches for Blepharoptosis
The management of blepharoptosis is tailored to the cause, severity, and levator muscle strength. Options are divided into non-surgical and surgical categories. Non-surgical approaches are for milder cases or for those who are not surgical candidates. One option is a “ptosis crutch,” a small bar attached to eyeglasses that supports the drooping eyelid.
A more recent non-surgical option is a prescription eye drop with oxymetazoline hydrochloride 0.1%. This medication stimulates the Müller’s muscle, a secondary eyelid elevator, causing it to contract and provide a temporary lift of 1 to 2 millimeters. It is most effective for certain types of acquired ptosis.
Surgery is the most common treatment for significant ptosis, and the procedure is chosen based on levator function. For patients with good muscle function, a levator resection is often performed. The surgeon makes an incision in the eyelid crease to access and tighten the levator aponeurosis, lifting the lid.
For severe ptosis with poor levator function (less than 5 mm), a frontalis sling surgery is the preferred technique. This procedure connects the eyelid to the frontalis muscle in the forehead using a suspensory material, like a silicone rod. This allows the patient to use their forehead muscles to elevate the eyelids, bypassing the weakened levator muscle entirely.