1. Single vision glasses
This is the simplest glasses for the degree of the whole lens remains all the same and thus can only be used for reading other than see things far away or in the medium. So if a person suffers from both myopia and hyperopia at the same time, then he needs to pairs of glasses: one for myopia and the other for hyperopia. In the daily life, he needs to taking off and putting on glasses often in order to see things clearly. The advantages the single vision glasses (http://www.finestglasses.com/
Target groups: are those who need to wear glasses for reading instead of seeing things far away for their vision is okay; especially for those whose occupation is writer, accountant, or draughtsman etc.
Note: although one can adjust to such glasses quickly, but the inconvenience lies in the fact that one cannot see things far away or nearby at the same time with wearing just one pair of single vision glasses.
As the name suggested, bifocal glasses (http://www.finestglasses.com/
Target groups: all the people who suffer from presbyopia, especially those who need to see things far away and nearby at the same time without taking off and putting on glasses frequently.
Note: the wearers need some time to adjust for their eyeballs need to move upward when they want to see far away and move downward when they want to see things nearby.
3. Progressive glasses
There are four parts in a progressive lens, namely the distance part, the mid-range, the near part and the edge part. The four parts enable the wearers to see things clearly at different distance with only one pair of glasses. Progressive glasses meet both the physical and psychological requirements of modern senior citizens.
Target groups: all the presbyopia sufferers especially those who need to see thing in all distance frequently and who pursue life with high quality, those who are over 55 when wearing glasses for the first time, or those who suffer from serious astigmatism or anisometropia.
Note: to wear progressive glasses, one needs some time for adjustment and training, each for about 1 to 2 weeks. When see things at different distance, one need to turn his/her eyeballs to different part in order to see clearly. And when see things from right to left, one also needs to turn his/her head from right to left. Therefore, those who suffer from disease, like cervical spondylopath, or inner ear disease, that makes him/her unable to move the head with flexibility are not recommended to wear progressive glasses (http://www.finestglasses.com/