Glasses with Plus (+) Number (Long-sight)
A plus power with low number is required for close work. Where the higher powers of +2, +3, +4, etc., are required, glasses must be worn constantly. There are special plus (+) glasses for the middle-aged group 40-42 years for work only. They increase in power with advancing age up to 60 yrs. This condition is called presbyopia. A ‘bifocal’ may be required in these age groups.