Differences between Trifocals and Bifocals

November 21st, 2009 by Arthur First Leave a reply »

Trifocals are a new group of special reading glasses which have three divisions on the lenses for correcting vision. It is different from traditional bifocals which have only two such divisions. The lower sections of the lens of trifocals are demarcated by a thin line which is a semi circular arc. One area is for near and the other for intermediate vision correction. And the part for intermediate rectification lies above the nearsighted correction area which is near the bottom of the lens. For those who used to wear bifocals may think it is strange to reading with glasses having three lines etched on it. As trifocals are new to most of people, it actually did need time for patient who uses this type of glasses to adjust to them. However, once you used to wear them, you will find it pretty easy to use and it is more convenient than bifocals.

After eye exam by the eye doctor, those people with extreme presbyopia, which means their net optical power with a special unit of diopter is very high, will be recommended to use trifocals. Because, unlike bifocals, trifocals can correct all ranges of vision, from nearby, intermediary to far distance, when bifocals can correct only two of them, either near vision or distance vision. Since trifocals can offer three levels of correction, it can give you a better vision. So, if you are one of the extreme presbyopia, you will get the better and more clarified vision when you use trifocals.

Trifocals are not only for those who have extreme presbyopia, it can also correct intermediate distance which can’t be provided by bifocals. For example, if your have a vision of -4 diopters, usually you will be recommended to use a glasses with a correction of 3 units, which means you vision is -1 diopter when you wear your reading glasses. The intermediate correction for such situation may be end up with a power of -2.5, which may take patients a little time to get used to it.

So with a single pair of trifocals, you can solve all problems that are related to presbyopia.


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