Bilateral ptosis is not seen in:
Ptosis does not occur in Marfans syndrome. Ref: Management of Genetic Syndrome By Suzanne B, 3rd Edition, Page 509 ; Clinical Ophthalmology By Kanski, 3rd Edition, Page 493 and 4th Edition, Page 180-1, 376-77 3. Comprehensive Ophthalmology By A K Khurana, 4th Edition, Page 202
Marfan's syndrome
Myaesthenia gravis
Myotonic dystrophy
Kearns sayre syndrome