What condition is characterized by a drooping eyelid?

The condition characterized by a drooping eyelid is known as ptosis. Ptosis can occur due to various reasons, including weakness of the muscle that raises the eyelid, nerve damage, or as a result of aging. It can affect one or both eyelids and may impact vision if the droop is severe enough to obstruct the visual field.

In contrast, blepharitis refers to inflammation of the eyelids, which typically manifests with symptoms like redness, irritation, and flaking but does not directly cause the eyelid to droop. Strabismus involves misalignment of the eyes and does not typically cause eyelid drooping either, although it may be associated with other visual problems. Myasthenia gravis is a neuromuscular disorder that can cause muscle weakness, including that of the eyelids, which can lead to ptosis. However, ptosis specifically describes the drooping itself, highlighting why it is the most direct answer to the question about drooping eyelids.