*Congenital *Aging creating loose skin and stretched and loose ligaments and muscles (senile<unk> . *Scarring (mechanical<unk>  *Spasm *An eye infection called trachoma is still common in North Africa and South Asia and this can cause scarring of the inner eyelid, which may cause friction and<unk> .
Entropion
Ectropion
Methylphenidate
Hydroxybupropion
Atomoxetine
Bupropion
Guanfacine
Mipomersen