Ptosis

Cranial nerve 3 palsy (dilated or normal pupil), eg, diabetic neuropathy, posterior inferior cerebellar artery (PICA) aneurysm
Horner’s syndrome (constricted pupil)
Myasthenia gravis
Botulism
Age-related (sagging eyelid)
Eyelid inflammation or deformity
Congenital
Progressive external ophthalmoplegia (mitochondrial myopathy)