Dioptric powers

• from 40 to 45 yrs :
  reading glasses +1.00
• from 45 to 50 yrs :
  reading glasses +1.50
• from 50 to 55 yrs :
  reading glasses +2.00
• from 55 to 60 yrs :
  reading glasses +2.50
• more than 60 yrs :
  reading glasses +3.00