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Evaluation of the performance of spectacle lens "transmittance meters"
1College of Optometry, University of Houston, Texas.
Purpose:
Inexpensive transmittance meters have recently been developed for measuring of mean ultraviolet (UV) radiant transmittance and luminous transmittance of spectacle lenses. Our purpose was to determine how accurately these meters measured transmittance.
Methods:
The mean UV transmittance and the luminous transmittance of a series of lenses were determined using a spectrophotometer. Transmittance meters were then used to measure the same lenses.
Results:
In general, the meters overestimated total (mean) UV transmittance. Luminous transmittance was relatively accurately measured by those meters which had this capability.
Conclusions:
Although the meters do not measure UV transmittance accurately, they are still useful for determining if a lens transmits any UV radiation. The relatively narrow response range of the meters, centered at 360 to 380 nm, is responsible for the measurement error of mean UV transmittance.