The most common cause of drooping eyelid is old age. The normal aging process can weaken the muscles around the eye that keep the lid open. In addition, the skin around the eyelid loses elasticity. Both of these processes can lead to drooping eyelid.

Temporary swelling of the eyelid can cause drooping eyelid.

Conditions that cause swelling of the eyelid include:

• Blepharitis
• Chalazion
• Conjunctivitis
• Hordeolum
• Subconjunctival hemorrhage

The eyelids are held open by muscles in the face. The brain sends signals to nerves that stimulate the muscles. If these signals are interrupted, the muscles become weak and drooping eyelid can occur.

Conditions that can interrupt these signals include:

• Brain tumor
• Diabetes
• Facial nerve injury
• Horner's syndrome
• Migraine headache
• Multiple sclerosis
• Myasthenia gravis
• Spinal cord injury
• Stroke