Efficacy and durability of ultraviolet tints in CR-39 ophthalmic lenses.
BACKGROUND
Ocular protection from solar ultraviolet (UV) radiation has been emphasized in recent years as a result of the thinning of the ozone layer in the atmosphere. The purpose of this study was to evaluate the absorptive properties of UV tints in CR-39 lenses.


METHODS
We used a spectrophotometer to measure the UV transmittance of three groups of UV tinted CR-39 lenses, including (1) lenses tinted by local optical laboratories: (2) lenses tinted by us, using commercially available dyes: and (3) stock UV lenses that have UV absorptive molecules throughout the lens. We also tested the durability of these tints to daily washing/drying by measuring their UV transmittance characteristics at 3, 6, and 12 months.


RESULTS
All the tested lenses absorbed all of the UV-B and at least 99% of UV-A. The durability of these UV tints when exposed to daily washing/drying was excellent: all lenses continued to absorb all of the UV-B and at least 99% of UV-A after 1 year.


CONCLUSIONS
These data suggest that UV tinted CR-39 lenses provide protection against UV radiation that meets the ANSI Z80.3-1996 Standard for non-prescription sunglasses and fashion eyewear. Furthermore, normal daily washing/drying for 1 year does not cause a significant decrease in the protective effect of the UV tint.
Lee
D Y
DY
Illinois College of Optometry, Chicago, USA.
Brown
W L
WL
Trachimowicz
R
R
D004389:Durable Medical Equipment / Q000592:standards*; D004781:Environmental Exposure; D005139:Eyeglasses / Q000592:standards*; D005374:Filtration; D006801:Humans; D007909:Lenses / Q000592:standards*; D008422:Materials Testing; D013053:Spectrophotometry; D014466:Ultraviolet Rays