Do you have multiple vision problems? If you do, it's time for you to consider using multifocal glasses. Amongst the various lenses available, the most common ones are bifocals. Bifocals help in aiding the vision but using it means you need to use it every time. Usually bifocals are prescribed to those who are suffering from presbyopia which is caused due to gradual failure of the flexibility of the lenses inside the eye.

Trifocals fall in the category of multifocal lenses. Such lenses are followed by three different stages of prescription. This is applicable for vision problems of any distance. In trifocals there are three levels of correction long, middle and short distance. If someone is suffering from presbyopia seriously then trifocals prove to be immensely helpful as they are advised to use two or more diopters.

In case of intermediate addition, it is usually half the reading addition. If you are provided with a prescription of -4 diopter and reading addition of +3 then the trifocals reading part is going to have a power of -1. In this case, in between section is likely to be -2.5 diopters.

The near vision correction and the intermediate are together placed in a half circular space at the bottom of each lens. There is a this line of demarcation between the two as well as with half circle.

• The bottom segment of the half circle is for near vision. When the reader has to pay close attention on objects closer to his eyes, he or she will have to look through this segment.

• Above this lies the intermediate zone. This part of the lens is used when the reader has to look at objects placed at an arm's length. The intermediate range is the shortest but it can be enlarged if it is required by the reader.

• The top section of the lens is used to see anything beyond an arm's length. This section can be adjusted to cater to the person's other vision problems such as myopia and hyperopia.

Presbyopia sets in people after their midlife. This makes reading glasses an absolute necessity for them. Presbyopia is a condition that occurs due to aging of eyes. It is different from hyperopia or farsightedness. Although this type of eye disorder cannot be cured, however it can be treated through various options such as Lasik surgery, or by wearing reading glasses or contact lenses.

Trifocals are very helpful as they enable the reader to look at different ranges clearly. Thus there is no need to carry three different glasses for different ranges. However, many people don't like the lines that are present across reading lenses. For such individuals there are progressive lenses, better known as progressive addition lenses (PALS), progressive power lenses, varifocal or graduated lenses. Such lenses don't have any lines on them. Therefore these lenses offer maximum comfort along with clarity of vision for the wearer.

Before you go and buy a pair of glasses for yourself, be sure to consult an eye specialist who will be able to prescribe you the perfect lenses that would help you with your vision problems. Take care!