| Abstract |
Purpose: In this study, spectroscopic analysis of a series of ophthalmic lenses, sunglasses of different darkness and sunglasses of unknown darkness was performed. The purpose of the study was to investigate the assumption that the lenses (ophthalmic or for sun) placed on the market meet the certification requirements of the European Certification Standard (CE), which requires less than 5% transmissivity for wavelengths less than 380nm. For this test, spectroscopic measurement of transmissivity was performed on each lens sample.
Methodology: 32 lenses (from 4 companies with 5 different coatings and various refractive indices 1,50 , 1,60 and 1,67) were measured in this study. Additionally it should be noted that the ready-made glasses for presbyopia as well as the 2-color photo-chromic lenses were studied when they were discolored by 2% and 5%), 9 sunglasses with unknown darkness (from street vendors in different areas of Athens) and 15 sun-protective lenses (from 3 companies with 2 different coatings and different refractive indices of 1.50 and 1.60 in 2 different darkness levels of 50% and 90%). The lenses were measured with the Lambda 950 and Lambda 25 spectrometer (PerkinElmer, Shelton, USA). The transmissivity of each lens was measured separately to determine if the lenses meet the European certification standard, where the 380nm transmissivity of each lens is less than 5% or the American certification standard, where the 400 nm per transmissivity of each lens is less than 5%. In addition, the reduction in brightness sensitivity was studied in 2 different age groups of a) 20-29 years and b) 60-69 years, when sunglasses of unknown darkness or sunglasses of 50% and 90% darkness were used. The measurement data of each lens were analyzed separately through the database that was developed.
Results: The results showed that for the ophthalmic lenses of refractive index 1,50 and in all the coatings, no company meets the certification criteria for the European and American standards, except for the company (1) for their photo-chromic lenses. For the refractive index 1,60 only the coating 1 does not meet either of the two certification standards, while the other coatings meet only the European certification standard. In addition, the refractive index 1,67 of the company (1) and (2) concerning the 3 coatings, meets the European standard, while for the European standard only the company (1) in coatings 2 and 3 fulfills the criterion. For company (4), only one lens meets both certification standards. With regard to sunglasses with different darkness, the refractive index 1.60 with a 90% darkness meets the European certification standard in both coatings with respect to the refractive index 1.50, of 90% and 50% darkness in each coating. Finally, Class 4 sunglasses meet the European and American standards but greatly reduce visible light (400-700nm).
Conclusions: Companies should systematically check the eye protection level of the lenses against the ultraviolet radiation, as their use is not limited to indoor environments. Sun lenses with different darkness, should protect the eye 100% from ultraviolet radiation as long as their use is outdoors without greatly reducing the brightness in the visible spectrum (400nm-700nm). As for the sunglasses (of unknown darkness) from street vendors, even if they meet both the European and American CE certification standards, they provoke a great reduction in the visible spectrum, which in some cases makes them dangerous. Finally, we propose there should be a specialized lab in Europe, to examine all the ophthalmic lenses of each company before their launch into the sales market and to make the appropriate recommendations to the companies if necessary.
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Φασματοσκοπική ανάλυση φακών οράσεως και ηλίου
