Single Vision
A progressive eyeglass wearer needs a frame with
- A minimal vertex distance
- Adequate pantoscopic tilt
- Sufficient vertical depth in the nasal portion of the frame shape
A minimal vertex distance is necessary because of the relatively narrow viewing areas afforded by the progressive lenses for intermediate and near distances.The closer the progressive viewing zone is brought to the eye, the wider the intermediate and near viewing areas will be
Using a frame with an adequate pantoscopic tilt will also help bring the lower half (reading half) of the lens closer to the eyes. When the eyes are turned downwarded for near viewing, the reading width will be increased.
The Shapes of frame is important with progressive addition lenses. When the lens is too narrow vertically, much of near viewing area will be consumed (See Image Below). If the lens has too much of the lower nasal area cut away as with the classic aviator shape, the reading area is severly reduce. A good frame shape for progressive lens has a sufficient vertical depth and not much nasal cut. The design for a progressive addition lens is one that has extra vertical depth in inferior, nasal portion of the shape.
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