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Durability of photometric and radiometric properties of non-prescription sun eyewear following simulated care

1 May 2003


Introduction. Consumers are presented with a vast array of available sunglass options. Choices for non-prescription sun eyewear include not only frame style, lens color, and tint density, but, most importantly for some consumers, cost, which may vary from under one dollar to over one hundred dollars. Yet all eyewear manufacturers claim to comply with standards designed to protect ocular health by reducing the amount of ultraviolet (UV) radiation to reach the eye. hTV absorbers can be applied to a lens as either a coating or a dye. Previous studies assessed characteristics of non-prescription sun eyewear at the point of sale and durability of UV absorbance of prescription eyewear following simulated care. The current study assessed the durability of UV absorbance and other photometric properties of typical non-prescription sun eyewear following one typical season of simulated cleaning with two conventional regimens, as well as one cycle of cleaning with two unconventional methods.

Methods. We purchased six pair of non-prescription sun eyewear marketed for bright outdoor conditions from each of three cost categories: under $1 5; $1 5 to $30; and over $30. During the first cleaning cycles, the left lens of each eyewear was cleaned with a water-based cleaner available at any optical dispensary, and dried with a soft cloth diaper. The right lens was cleaned with Ivory Liqui-Gel soft soap and warm water, and dried with a Puffs brand tissue. Lenses were cleaned for three cycles of care, each of which simulated 13 weeks. Lenses were then divided into two groups for one additional cleaning cycle. One group was cleaned with 70% isopropyl alcohol and the other group was cleaned with Windex, active ingredient ammonia. Spectrometry from 200 to 1100 nm, in 5-nrn increments, was conducted on each lens at baseline and after each cleaning cycle.

Results. At baseline, one pair of bargain-priced eyewear did not meet minimum requirements for UV absorption. Several other eyewear did not meet standards for other optical characteristics, such as suitability for driving and for color deficient individuals. However, 9 months of simulated cleaning with a recommended cleaner or soft soap did not alter UV absorbance of any of the eyewear. Likewise, 3 months of simulated cleaning with alcohol or glass cleaner had no affect on UV absorbance of any eyewear. For any cleaning regimen, changes to other photometric characteristics were typically within the measurement tolerance of the spectrophotometer and likely not clinically significant.

Conclusion. While there is considerable variability in optical characteristics of non-prescription sun eyewear at baseline, simulated cleaning did not affect the optical performance of any eyewear. Consumers should be confident that most name brand eyewear purchased from a reputable retailer complies with optical and ocular health standards, and that it will withstand a season of typical cleaning. In addition, dispensers should not be concerned about using alcohol to clean eyewear. Key Words: non-prescription


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