Ptosis can be present from birth, Congenital Ptosis, as a result of the muscle that lifts the lid not developing properly. Occasionally ptosis can be inherited from family members with the condition. Causes of the, more common, Acquired Adult Ptosis can be divided into 5 categories:
Aponeurotic:
The levator muscle which lifts the lid is attached to the lid by a sheet of tissue, called the aponeurosis, which can be damaged by natural ageing, contact lens use or persistent eye rubbing.
Neurogenic:
The oculomotor nerve and the sympathetic nerves that control the eyelid muscles can be affected by various conditions including third nerve palsy and Horner’s Syndrome.
Myogenic:
The levator muscle can be weakened by systemic conditions such as myotonic dystrophy, muscular dystrophy, myaesthenia and chronic progressive external ophthalmoplegia.
Mechanical:
The lid can be too heavy for the levator muscle to lift as a result of blepharochalasis, orbital fat prolapse or eyelid tumours.
Traumatic:
Trauma to the eyelid can cause disinsertion, damage or scarring of the levator and its aponeurosis.
