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What Are Trifocal Eyeglasses?

Eyeglass lenses have developed over time from single-vision focal lenses to more advanced trifocal lenses. If you have vision problems, especially for perceiving near and far objects or if you find yourself constantly holding the newspaper farther away to be able to read it, you may be a candidate for trifocal lenses.

  1. Trifocal

    • Trifocal eyeglasses have lenses with three focal points. While many vision-impaired people only need single-vision lenses, some have more advanced eye prescriptions requiring multifocal lenses. This type of lens helps correct several vision problems with just one pair of eyeglasses. Trifocal lenses typically have focal points for distance, intermediate and near vision, which are separated by segments on the lens. The segments come in a variety of shapes and widths.

    Types

    • Different types of trifocal lenses are characterized by the way the focal segments are arranged on the lens. Common types of trifocals include flat top, double-D and E-D. Flat top trifocals are also called D segment because they have a D-shaped segment on the lower part of the lens, usually 28 millimeters wide. The "D" is upside down with the curve part of the D parallel to the bottom of the frame. The small top portion of the "D" has a separate focal segment.

    Progressive

    • Instead of clearly defined and visible segments, many trifocal lenses are progressive. This feature allows the segments to blend seamlessly so that your glasses do not appear so thick. Progressive, trifocal lenses gradually change in power from the top half portion to the bottom part of the lens. This is often considered more aesthetically pleasing than visible line segments. Aside from being discreet, progressive lenses also provide a comfortable power transition instead of three separate lens powers, making them a better visual aid.

    Presbyopia

    • Eye care patients who need trifocals are suffering from a condition called Presbyopia. This condition makes it difficult for patients to see objects closely because the lens of the eye have lost their elasticity and ability to focus. Presbyopia is an age-related condition that usually occurs around the age of 45.

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