When it comes to prescription glasses, the choices are many. Your prescription can depend on your eye disorder, your personal preference and your budget. Here are a few options to select from.
Single vision prescription glasses are all-purpose, and will suit most people with vision problems. They have a single field of focus. They either concentrate on distance vision, near vision or intermediate vision. Sunglasses are usually single vision glasses.
Though a bifocal seems to be a single lens, it is actually composed of two lenses that have been combined. You might have seen one of these, where a visible line separates two view zones. The part above the line is for distance vision and the part below facilitates near vision. Basically bifocals have two different optical powers in a single lens. It is usually used to treat presbyopia.
Trifocals have three different focal points for distance vision, near vision and intermediate vision. They have an added segment usually above the near zone, for viewing objects at an arm’s length. For example, a computer terminal may in the intermediate zone. But the use of trifocals is becoming rarer, because more and more people are shifting to the use of progressive lens. Trifocals are especially useful to motorists.
Progressive lenses are also known as multi-focal or varifocal lens. They have a characteristic increasing power gradient. The gradient begins at the top of the glasses and reaches a maximum reading addition at the bottom. Progressive are useful because they avoid image jumps that are characteristic of bifocals and trifocals. They are more aesthetic to look at and just by tilting your head to a particular angle you can adjust your vision to the vertical progression.