Ptosis can be caused by the apneurosis of the levator muscle, nerve abnormalities, trauma, inflammation or lesions of the lid or orbit.
Dysfunctions of the levators might occur as a result of a lack of nerve communication being sent to the receptors due to antibodies needlessly attacking and eliminating the neurotransmitter.
Ptosis might be due to a myogenic, neurogenic, aponeurotic, mechanical or traumatic cause and it usually occurs isolated, but might be associated with various other conditions, like immunological, degenerative, or hereditary disorders, tumors, or infections
Acquired ptosis is most commonly caused by aponeurotic ptosis. This can occur as a result of senescence, dehiscence or disinsertion of the levator aponeurosis. Moreover, chronic inflammation or intraocular surgery can lead to the same effect. Also, wearing contact lenses for long periods of time is thought to have a certain impact on the development of this condition.
In this case, a mild ptosis might be associated with psilateral ptosis, iris and areola hypopigmentation and anhidrosis due to the paresis of the Mueller muscle. Acquired Horner syndrome might result after trauma, neoplastic insult, or even vascular disease.
Ptosis due to trauma can ensue after an eyelid laceration with transection of the upper eyelid elevators or disruption of the neural input.
Other causes of ptosis include eyelid neoplasms, neurofibromas or the cicatrization after inflammation or surgery. Mild ptosis might occur with aging.