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KMID : 1159320150170010001
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Korean Journal of Vision Science
2015 Volume.17 No. 1 p.1 ~ p.8
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Evaluation of the Fading Rate of Photochromic Lenses by Coating
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Yu Dong-Sik
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Abstract
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Purpose: The aim of this study was to investigate and compare optical properties focussing on the fading rate of photochromic lenses, which were prepared by in situ hard and photochromic coating.
Methods: Photochromic dyes with red, yellow and blue were mixed in the hard coating solutions,which were composed by tetraethyl orthosilicate and 3-glycidoxypropyltrimethoxysilane. Photochromic coatings were prepared on plastic ophthalmic lenses by flow coating and cured thermally. The optical properties and surface characteristics of the coated lenses were evaluated.
Results: The photochromic lenses by coating showed good adhesion, stronger surface hardness than uncoated lenses. Maximum absorbances (λmax) for photochromic lenses with red, yellow and blue dye were 499, 418, 606 nm, respectively. Fading rates based on half-life time at λmax were 204, 416, 670 sec in order of blue, red and yellow photochromic lenses. The fading rate of blue dye with spironaphthoxazines was faster than that of red and yellow dye with naphthopyrans, and that of the same classes was fast with increase of thermal stability in colorless state.
Conclusions: Fading rates of the photochromic lenses by coating depend on characteristics of photochromic dyes involving thermally reversible stable form. Therefore, in photochromic coatings, the intrinsic fading rate of photochromic dyes may be considered prior to coating compositions.
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KEYWORD
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Photochromic lenses, Photochromic dyes, Coating, Fading rate
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