Saturday, February 7, 2009

Be Aware of Multifocal Glasses!

Some people have referred feeling dizziness or suffering from back/neck pain after wearing multifocal lenses. Some also referred having difficulties calculating spatial distances when going up or down the stairs.
Difficulty in going up or down the stairs is often thought to be related with the power of the lenses for near sight. The maximum power added for near sight in a multifocal lens is 3.50. This means that if the user uses the near focus by mistake, he temporarily suffers from a 3.50 diopters' myopia.
A 3.50 diopters' myopia does not cause difficulty in going up or down the stairs without glasses.
The reason for these symptoms must be related to the prismatic action of those lenses.
The solution is not to avoid multifocals but to eliminate the prisms that the factory is incorporating in order to get thinner lenses. Nowadays, this technique is not so useful as before for this prescription because the modern materials associated with the pre-calibration technique allows to obtain thin lenses.

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