A drooping eyelid or ptosis can be present at birth (congenital) or can occur later in life (acquired). Poor development of the levator palpebrae superioris muscle in the upper eyelid can lead to an inability to properly open the eye. It is the most common cause of congenital ptosis. Acquired ptosis has many possible causes. Ptosis can involve one or both upper eyelids, with or without symmetry [See figure 1].
One or more of the following abnormalities may accompany ptosis in childhood: astigmatism (refractive error), obstruction of the visual axis (the path that light takes into the eye), a chin-up head position, and amblyopia. The abnormal resting position of the eyelid on the cornea may result in astigmatism (a misshaping of the cornea) or other refractive errors, and is a risk factor for developing amblyopia (refractive amblyopia). Another risk factor for amblyopia is an eyelid drooping so low that it actually prevents light from entering the eye and creating an image on the retina at the back of the eye (deprivation amblyopia) Also, a chin-up head position may be present. This head position is adopted in order to be able to see beneath the edge of the drooping upper eyelid. Contraction of the frontalis muscle (in the forehead) to further elevate the upper eyelid is a very common compensatory mechanism.
Acquired ptosis can be caused by neurologic conditions that affect the nerves and/or muscles of the eye. These include myasthenia gravis, progressive external ophthalmoplegia, Horner syndrome, and third cranial nerve palsy. The ptosis may be combined with an eye movement disorder with resultant double vision. An eyelid mass can also cause ptosis.
The Eye M.D. typically inquires as to the time of onset, variability, and presence/absence of double vision, which may aid in determining the cause of the ptosis. A complete eye examination is performed with special attention given to the eyelid position, vision assessment, refraction, and the head position. Special tests such as radiographic exams (x-rays or CT scans) are not commonly ordered.
When amblyopia is present, appropriate treatment is initiated. When astigmatism is significant enough to potentially cause amblyopia, glasses are prescribed. Early eyelid surgery is usually indicated for a drooping eyelid that blocks vision (which may cause delayed vision development), or leads to a significant chin-up head position (which may cause neck problems and/or delay of developmental skills). Children are usually monitored regularly for vision abnormalities. Surgery may also be indicated during preschool years if the ptosis does not improve with normal growth and maturation of the face.
More technical information may be found on the EyeWiki Site.
Are you a medical professional, interested in joining AAPOS? Find out more here ▶