How many types of glasses are there?  

• Single lens (Single Vision) lens is used to solve any long term vision.
• Four multi-lens collection (Multifocal) is a lens that allows users to see multiple stages. both near and far. The top lens will help to see the distance vision more clearly. And the lens below will help to look at close objects such as reading a book. or sewing.

Four multi-lens eyewear collection is used to adjust the sight of people with presbyopia by age discernible objects near the focus. It is divided into several types of lenses with different properties as follows:   

• Double lens (Bifocals) consists of parts that can be seen in the near term. which is below the lens and the part that can be seen in the distance which is at the top of the lens. There is also a special type of bifocal lens with a joint on top. For those who need to look at objects at a close distance or in the middle at a high angle.
• Three-layer lens (Trifocals) is a three-stage lens in the lens is long-term and near-term.
• Progressive lenses ( Progressive the) features a two-layer optical lenses and three floors. But users can see objects from a distance to a close continuous seamlessly. The focusing area of ​​this lens is quite small. This is because most of the lens area is used to connect the field of vision. But progressive lenses can cause eye discomfort. and dizziness while wearing more than other types of lenses This lens is therefore the type that people use less frequently.