Ptosis refers to drooping of an upper eyelid of one or both eyes. The droop may be hardly visible, or the lid can move down over the entire pupil. Ptosis can affect both children and adults, however more often than not happens for the reason that of aging. In some cases, droopy eyelid is caused by additional grim circumstances, such as a stroke, brain tumor, or cancer of the nerves or muscles. Neurological disorders that affect the nerves or muscles of the eyes , such as myasthenia gravis can also lead to ptosis.