Droopy eyelid (ptosis) explained

A drooping upper eyelid, and why it is often misunderstood

Ptosis, pronounced toe-sis, simply means a drooping of the upper eyelid. The eyelid margin, the edge where the lashes sit, rests lower than it should. It can affect one eye or both, and it ranges from a barely noticeable difference between the two sides to a lid that droops far enough to cover part of the pupil and get in the way of seeing.

The upper eyelid is held open by a muscle called the levator, which runs from deep in the socket to the eyelid, helped by a smaller muscle behind it. When this muscle, or more often the fine tendon that attaches it to the eyelid, stretches or works less well, the lid sits lower than normal. That, in essence, is ptosis.

The causes, from ageing to nerves and muscles

Age-related, by far the most common

In the great majority of people I see, ptosis develops slowly with age. The tendon that connects the lifting muscle to the eyelid gradually stretches or partly comes away from its attachment, so the muscle still works but no longer lifts the lid as high as it used to. This is called aponeurotic or involutional ptosis. A useful clue is that the eyelid crease often sits higher than normal. It is more common after cataract or other eye surgery, and in people who have worn contact lenses for many years, because both can stretch the same tendon over time.

Present from birth

Some children are born with a droopy eyelid because the lifting muscle did not develop fully. This matters more than it does in adults, because a lid that covers the pupil during the years when vision is developing can hold back the sight in that eye, a problem called amblyopia or lazy eye. For that reason a droopy eyelid in a baby or young child should always be assessed promptly, even if it seems mild.

Nerve-related causes

The eyelid muscles rely on their nerve supply, and several nerve conditions can cause drooping. A third nerve palsy tends to cause a more sudden droop, often with the eye turned down and out and sometimes an enlarged pupil, and can occasionally be due to a problem with a blood vessel that needs urgent attention. Horner’s syndrome causes a milder droop alongside a smaller pupil on the same side, and is occasionally a sign of a problem in the neck. Myasthenia gravis, a condition affecting the junction between nerve and muscle, causes drooping that comes and goes, is typically worse when you are tired or later in the day, and may be accompanied by double vision.

Muscle conditions, and lids weighed down

Less commonly, the muscle itself is affected by an inherited or acquired muscle condition, which tends to cause a slow, steady droop in both eyes over years. A droopy eyelid can also be purely mechanical, where a cyst, lump, or swelling simply weighs the lid down, in which case treating the lump resolves the droop.

How a droopy eyelid affects you

The most obvious sign is the appearance of the lid itself, but a droopy eyelid often does more than change how you look. As the lid drops into the upper part of your vision, it can narrow your field of view, particularly when you look up or read, so people describe missing things above them or feeling that the eye is half closed. Many find themselves lifting their eyebrows or tilting their head back to see more comfortably, which can lead to a persistent ache across the forehead by the end of the day. The eyes can feel heavy and tired, and the difference between the two sides is often more noticeable in photographs or when you are fatigued.

In children, the signs to look for are a lid that sits low over the eye, a chin-up head position, or a tendency to raise the brows to see, all of which are reasons to have the eyes checked.

The signs that deserve prompt attention

Most droopy eyelids come on slowly over months or years, are age-related, and are not dangerous. A smaller number come on quickly or carry other features, and these are the ones worth acting on sooner rather than later, because they can point to a nerve or muscle cause.

If none of these apply and the drooping has crept up gradually over a long period, it is very unlikely to be anything sinister. It is still worth having assessed, because identifying the cause means any treatment can be aimed at the right thing rather than guessed at.

How a droopy eyelid is assessed and treated

Assessment comes first, and it is more than a glance. In clinic I measure how low the lid sits and, importantly, how well the lifting muscle is working, because that single measurement largely determines which operation is appropriate. I also check the pupil and eye movements and ask whether the drooping varies, since these help separate a straightforward age-related droop from a nerve or muscle cause that needs treating in its own right.

For the common age-related ptosis, surgery is the reliable treatment. The principle is to tighten or reattach the stretched tendon so the lid is lifted to a more natural height. In many cases this is done through a fine incision hidden in the natural eyelid crease. Where the muscle is working well and the droop is mild, it can sometimes be corrected from behind the lid with no visible incision at all. Where the lifting muscle is very weak, which is more often the case in children, a different technique is used that harnesses the brow to raise the lid. These procedures are usually carried out under local anaesthetic as day cases, and the aim throughout is to restore a natural, symmetrical eyelid height while making sure the eye can still close and stay comfortable.

It is worth saying that not every droopy eyelid is treated with surgery. Where the cause is a condition such as myasthenia, treating that condition is what matters first. And ptosis is not the same as a blepharoplasty, which removes excess skin. The two are often confused and sometimes combined, but they correct different problems. If you would like to understand the distinction, I have written a separate guide on blepharoplasty versus ptosis repair.