An assigned period of time for an elected official

It's called a term. When a elected official serves an certain amount of time in office. That's called a term because they're serving for a given number amount of time in a certain period. 

It is a rice industry

True blindness may be caused by trauma to the eye, severe conjunctivitis due to  ibr (infectious bovine rhinoceros) or pink eye or other infections, leptospirosis, lead poisoning, selenium toxicity, fungal infections, vitamin a  deficiencies, rabies, vitamin b12 deficiency, neoplastic of the orbit or  conjunctiva, cataracts, congenital malformations, etc.