Hi Cataract is an aging lens of eye. So the way you can't avoid aging..same way you can't avoid cataract .But if you follow good life style , diet , avoid UV rays, take supplements, don't have other illnesses  ..May be you will get little later in life. How do kings n all tackle cataract..Will have to look in history books. But I am guessing same way as common men but in fancier set ups and by  costlier surgeons?  But no need to worry..we have very good treatment for it.