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Progressive addition lenses--matching the specific lens to patient needs
1Vision Ergonomics Laboratory, USA. jsheedy@optometry.osu.edu
Background:
The objective of this study was to use state-of-the-art methods to measure the optical characteristics of commonly available progressive addition lenses (PALs) and to develop derivatives of the optical measurements that can be used as guidelines in selection of lenses based on patients' visual needs.
Methods:
The optics of 28 PALs currently on the market were measured with a Rotlex Class Plus lens analyzer. PALs were specified with plano distance power and a near add of +2.00 D. Data were normalized to plano at the location specified by each manufacturer and acquired from each data file in 1-mm vertical steps with respect to the fitting cross.
Results:
The variance across lenses was greater than 2:1 for most measurements. Ratings were calculated based on equal weighting of zone width and area for distance, intermediate, and near zones, and also for magnitude of unwanted astigmatism.
Conclusions:
The results demonstrate wide ranges of optical characteristics across the PALs tested in this study. Ratings of the distance, intermediate, and near zones, as well as rating of unwanted astigmatism can be used in selection of appropriate lenses to match patient visual needs.