What Causes a Drooping Eyelid?

A drooping eyelid (ptosis) is when the upper eyelid sits lower than normal. There is no single cause; it may be present from birth or develop later with age, after an injury or due to a disease. Because treatment is planned according to the cause, identifying what is causing the droop is the first step.

Drooping Eyelid Present from Birth

A drooping eyelid present from birth is mostly caused by the muscle that lifts the eyelid (the levator muscle) not developing sufficiently in the womb. It can affect one eye or both. If the droop covers the pupil, it can affect visual development and lead to a lazy eye; for this reason early and regular eye examinations are important in children.

Drooping Eyelid That Develops Later

The main causes of a drooping eyelid that develops later are:

• Age-related loosening: the connective tissue by which the muscle that lifts the eyelid attaches to the lid loosens or thins over time. This is the most common cause.
• Contact lenses and eye surgery: long-term contact lens wear and eye operations such as cataract surgery can affect this connective tissue.
• Nerve damage: the nerve that controls the muscle that lifts the eyelid can be affected by diabetes, high blood pressure, blood vessel problems or pressure inside the skull. Conditions such as Horner syndrome can also cause a mild droop.
• Diseases of the muscles and of the nerve-muscle junction: in diseases such as myasthenia gravis, the droop may increase and decrease during the day and become more noticeable with fatigue.
• Mechanical causes: masses on the eyelid, swelling (oedema) or scar tissue can cause drooping by weighing the lid down or pulling it downwards.
• Injuries and medicines: blows to the eyelid can damage the muscle. A temporary droop can occur after botulinum toxin treatments around the eyes.

Unlike these, sagging eyelid skin or drooping eyebrows can also make the eyelid look as if it is drooping. This is called a false drooping eyelid; it is not a muscle or nerve problem.

How Is a Drooping Eyelid Diagnosed?

For diagnosis, the doctor first asks when the droop started, whether it has changed over time and what other complaints accompany it; old photographs can help determine when it began. At the examination, the height of the lid, the strength of the muscle that lifts the eyelid, eye movements and the pupils are assessed. If a muscle or nerve disease is suspected, additional tests such as a neurological assessment, blood tests or imaging may be requested.

Which Situations Require Urgent Assessment?

If a drooping eyelid starts suddenly and is accompanied by double vision, a difference in pupil size, a severe headache, restricted eye movements, or difficulty speaking or swallowing, a doctor should be seen urgently without waiting.

For the symptoms and treatment methods of a drooping eyelid you can read our article Drooping Eyelid (Ptosis): What Is It and How Is It Treated?, and for a droop affecting one eye our article Causes of a Drooping Eyelid on One Side.

Author: Op. Dr. Yücel Sarıaltın