Ptosis (pronounced toe' sis), or drooping of the upper eyelid, may occur for several reasons such as: disease, injury, birth defect, previous eye surgery and age. In most cases, it is caused by either a weakness of the levator muscle (muscle that raises the lid), or a problem with the nerve that sends messages to the muscle.
Children born with ptosis may require surgical correction of the lid if it covers the pupil. In some cases, it may be associated with a crossed or misaligned eye (strabismus). Left untreated, ptosis may prevent vision from developing properly, resulting in amblyopia, or lazy eye.
Patients with ptosis often have difficult blinking, which may lead to irritation, infection and eyestrain. If a sudden and obvious lid droop is developed, an eye care practitioner should be consulted immediately.
The causes of ptosis are quite diverse. The symptoms are dependent on the underlying problem and may include:
When examining a patient with a drooping lid, one of the first concerns is to determine the underlying cause. The ophthalmic surgeon will measure the height of the eyelid, strength of the eyelid muscles, and evaluate eye movements and alignment. Children may require additional vision testing for amblyopia.
Ptosis does not usually improve with time, and nearly always requires corrective surgery by an ophthalmologist specializing in plastic and reconstructive surgery. In most cases, surgery is performed to strengthen or tighten the levator muscle and lift the eyelid. If the levator muscle is especially weak, the lid and eyebrow may be lifted. Ptosis surgery can usually be performed with local anaesthesia except with young children.
Illustrations by Mark Erickson
With acknowledgement to St. Lukes Eye Hospital.