<P> Ptosis occurs due to dysfunction of the muscles that raise the eyelid or their nerve supply ( oculomotor nerve for levator palpebrae superioris and sympathetic nerves for superior tarsal muscle ) . It can affect one eye or both eyes and is more common in the elderly , as muscles in the eyelids may begin to deteriorate . One can , however , be born with ptosis . Congenital ptosis is hereditary in three main forms . Causes of congenital ptosis remain unknown . Ptosis may be caused by damage / trauma to the muscle which raises the eyelid , damage to the superior cervical sympathetic ganglion or damage to the nerve ( 3rd cranial nerve ( oculomotor nerve ) ) which controls this muscle . Such damage could be a sign or symptom of an underlying disease such as diabetes mellitus , a brain tumor , a pancoast tumor ( apex of lung ) and diseases which may cause weakness in muscles or nerve damage , such as myasthenia gravis or Oculopharyngeal muscular dystrophy . Exposure to the toxins in some snake venoms , such as that of the black mamba , may also cause this effect . </P>
<P> Ptosis occurs due to dysfunction of the muscles that raise the eyelid or their nerve supply ( oculomotor nerve for levator palpebrae superioris and sympathetic nerves for superior tarsal muscle ) . It can affect one eye or both eyes and is more common in the elderly , as muscles in the eyelids may begin to deteriorate . One can , however , be born with ptosis . Congenital ptosis is hereditary in three main forms . Causes of congenital ptosis remain unknown . Ptosis may be caused by damage / trauma to the muscle which raises the eyelid , damage to the superior cervical sympathetic ganglion or damage to the nerve ( 3rd cranial nerve ( oculomotor nerve ) ) which controls this muscle . Such damage could be a sign or symptom of an underlying disease such as diabetes mellitus , a brain tumor , a pancoast tumor ( apex of lung ) and diseases which may cause weakness in muscles or nerve damage , such as myasthenia gravis or Oculopharyngeal muscular dystrophy . Exposure to the toxins in some snake venoms , such as that of the black mamba , may also cause this effect . </P>
damage to this nerve can cause a drooping eyelid
damage to this nerve can cause a drooping eyelid
oculomotor nerve
oculomotor nerve