<prompt> Not a cause of pre-senile cataract:Diabetes mellitusMyotonic dystrophyPosterior polar cataractMarfans syndrome  <response>: Marfans syndrome is not a cause of pre-senile cataract. Pre-senile cataract Cataract onset before 50 years of age. Causes Diabetes Mellitus. Atopic dermatitis. Steroid Induced cataract. Posterior polar cataract. Myotonic dystrophy. 