ISSN(print) 1226-5012 22(1):23-31, March 2017 < 초청논문 > http://dx.doi.org/10.14479/jkoos.2017.22.1.23 Evaluation of Fading Rate of Photochromic Lenses in Domestic Market Dong-Sik Yu*, Hyun Gug Cho, and Byeong-Yeon Moon Dept. of Optometry, Kangwon National University, Samcheok 25949, Korea (Received February 1, 2017: Revised February 20, 2017: Accepted March 30, 2017) Purpose: This study aimed to evaluate the fading rate and factors affecting the performance of photochromic lenses. Methods: Thirty six brands of photochromic lenses were collected from 14 companies in domestic market. Transmittances (T%) of the lenses depending on time were measured within visible wavelength after activated (colored) state by UV irradiation. An UV/VIS spectrometer was used to obtain the transmittance. Fading rates were evaluated by half-life time (t 1/2 ), and fading time to the 80% transmittance (T 80% ). Results: The performance of photochromic lenses was better expressed as the difference between colorless and colored state (ΔT%) than the change of optical density (ΔOD) and optical blocking % ratio (block %). For the t 1/2 of photochromic lenses, coating method was significantly faster than those of imbibition and casting method (one-way ANOVA, p=0.001). For the T 80% of the lens with high index was significantly faster than middle index (student s t-test, p=0.034), and the lens with gray color was significantly faster than brown color (student s t-test, p=0.005). But the T 80% had no significant correlation with t 1/2. The photochromic action had a wide variety of 14.9% to 48.9% for ΔT%, 44 sec to 217 sec for t 1/2, and 127sec (2 07 ) to 3,523 sec (58 43 ) for T 80%. Conclusions: The performance of photochromic lenses based on fading rate had a large difference among brands. Therefore, the manufacture companies should provide consumer and agent with correct photochromic information (ΔT%, t 1/2, T 80% ) in relation to fading rate. Key words: Photochromic lens, Fading rate, Half-life time, Transmittance, Domestic market 서론광변색렌즈는자외선을흡수하면무색상태에서유색상태 (color state 또는 activated state) 로변하고, 빛을차단하면무색상태 (inactivated state 또는 colorless state) 로되돌아온다. [1] 이러한광변색렌즈는야외에서선글라스로, 실내에서는무색안경렌즈로사용할수있기때문에편리하다. 여름휴가철이나야외활동이증가하는시기에선글라스수요가많아지고이와더불어광변색렌즈의수요도늘어난다. 이에광변색렌즈제조사들은시장공략을위한저마다의기술력을강조해왔다. [2] 제조사들이강조하는비교대상의기술력의항목은변색속도 (activating rate 또는 darkening rate), 퇴색속도 (fading rate), 실내투명도 (transparency) 등이다. 이러한항목에대한제조사들의평가는자체브랜드제품이우수하다는것이다. 그러나각제조사간의상대적평가는찾아보기힘들고명확하지않아제품별특성을찾기힘들다. 유통되고있는광변색렌즈는대부분플라스틱렌즈로광변색물질 (photochromic dye) [3] 과플라스틱에적용시키는방 식, 즉캐스팅 (casting 또는 in-mass) 법, [4] 침투 (imbibition) 법, [5] 코팅 (coating) 법 [6] 에따라변색의특성에서차이를보이게된다. 그러나유통되는대부분의광변색렌즈는안경렌즈의광학적특성, [7] 즉굴절력, 굴절률, 중심두께, 투과율과색상에대한정보외에광변색에대한특성을파악하기힘들다. 이러한상황에서유통되고있는수종의광변색렌즈에대한광변색특성을비교할필요가있다. 지금까지의광변색렌즈의변색이나퇴색에관한연구에서 Jeong 등 [8] 은유통되고있는광변색렌즈의변색속도가 60~260 sec이며자외선의파장과렌즈종류에따라다르다고하였다. Kim 등 [9] 은광변색렌즈의광감성평가에서유색상태와무색상태의시간의존성에관한식을제시하였으나다양한광변색렌즈제품에대한평가는하지않았다. Yu [10] 는코팅방법으로제조한광변색렌즈의퇴색속도는코팅성분보다광변색물질이갖는고유의퇴색속도가중요하다고제기하였다. 그러나현재유통되고있는광변색렌즈는변색속도보다느린퇴색속도를보인다. 즉실내에서무색으로되돌아가는속도가느리다. 이러한느린퇴색속도는광변색렌즈의일반안경렌즈나선글라스기능 *Corresponding author: Dong-Sik Yu, TEL: +82-33-540-3415, E-mail: yds@kangwon.ac.kr 23
24 Dong-Sik Yu, Hyun Gug Cho, and Byeong-Yeon Moon 으로서장점을약하게하는요인이다. 이러한관점에서광변색렌즈는유통과정에서광변색렌즈의특성, 특히퇴색속도에관한정보를제공할필요가있을것이다. 따라서본연구의방향은국내유통되는광변색렌즈를중심으로제품별퇴색속도와제조방법, 색상, 굴절률차이에따른퇴색속도를중심으로퇴색의특성을파악하고자하였다. 대상및방법 1. 평가대상국내에유통되는렌즈중심으로 14개사 36개광변색렌즈를수집하였으며제품별명세서는 Table 1과같다. 색상은회색과갈색렌즈가각각 19개와 17개, 중굴절렌즈 22 개와고굴절렌즈 14개, 렌즈중심두께는 1.92~2.53 mm, 광변색렌즈의제조법은캐스팅 12개, 침투법 10개및코팅법 14개제품으로구성되었다. 2. 평가방법 1) 투과율측정광변색렌즈의투과율 (transmittance, T) 는 UV/Vis 분광광도계 (X-ma 2000, Human, Korea) 를사용하여 1 nm간격으로 380~780 nm까지측정하였고, 흡광도 (absorbance, A) 는일반적으로알려진투과율과의관계식, 즉 A=2-log(T) 으로환산하여사용하였다. 2) 퇴색속도결정광변색렌즈의퇴색속도를결정하기위해광변색전, 광변색후 0, 120, 240, 640 sec 간격으로투과율을측정하였다. 광변색렌즈는변색렌즈테스터기 (Quick, Nadokorea, Korea) 안에서 12초간 10회펄스 (pulse) 를가한후퇴색과정을평가하였다. 반감기 (half-life time) 결정은무색으로퇴색되는과정이분자내의폐환 (closed ring) 과정이며비가역단분자형 1차반응 [11,12] 으로다음반응속도에의해반감기를평가하였다. [10,13] ln A A t ------------- = kt A t 12 A 0 ln2 = ------- k (1) (2) 여기서 A t 는 t시간의흡광도 (absorbance after t), A 0 는초기흡광도 (absorbance in activated state), A는완전폐환된흡광도 (absorbance in colorless state), k는속도상수 (rate constant) 이고, t는반응시간이다. 따라서반감기는속도상수가결정되면식 (2) 에의해결정된다. 퇴색속도는가시광선영역에서최대흡광도를갖는파 Table 1. Specification of photochromic lenses with plano used in the study Photochromic lens Index CT, mm Manufacture process SWG5 gray 1.56 2.09 Casting SWG5 brown 1.56 2.09 Casting NKT5 gray 1.5 1.98 Imbibition NKT5 brown 1.5 1.92 Imbibition RDP5 gray 1.54 2.06 Casting RDP5 brown 1.54 2.07 Casting CVS5 gray 1.56 2.43 Casting CVS5 brown 1.56 2.45 Casting JAP5 gray 1.56 2.44 Casting JAP5 brown 1.56 2.50 Casting DMP5 gray 1.55 2.52 Casting DMP5 brown 1.55 2.53 Casting DMT5 gray 1.5 2.51 Imbibition DMT5 brown 1.5 2.50 Imbibition DMT6 gray 1.6 2.26 Imbibition DMT6 brown 1.6 2.36 Imbibition CMT6 gray 1.6 1.97 Imbibition CMT6 brown 1.6 1.98 Imbibition TOA5 gray 1.56 2.13 Imbibition YJG6 gray 1.6 2.00 Casting YJG6 brown 1.6 2.00 Casting OTS6 gray 1.6 1.98 Coating OTS6 brown 1.6 2.03 Coating HYS5 gray 1.5 2.25 Coating HYS5 brown 1.5 2.30 Coating HYS6 gray 1.6 2.04 Coating HYS6 brown 1.6 2.19 Coating CZP5 gray 1.5 2.17 Coating CZP5 brown 1.5 2.12 Coating CZP6 gray 1.6 2.16 Coating CZP6 brown 1.6 2.26 Coating SMS5 gray 1.5 2.06 Coating SMS5 brown 1.5 2.04 Coating SMS6 gray 1.6 2.04 Coating SMS6 brown 1.6 2.06 Coating Glass gray 1.52 2.47 Casting The first two characters mean initials of company names and the next one character indicates initials of brand names, a digit number indicate 5 for middle index and 6 for high index, the next words show colors of photochromic lenses. Index: middle index for 1.5-1.56 and high index for 1.6, CT: center thickness.
Evaluation of Fading Rate of Photochromic Lenses in Domestic Market 25 Table 2. Spectroscopic data for photochromic lenses in visible range Photochromic lens λ max T max ΔOD Transmittance in 380-780 nm range Colorless state % Colored state % ΔT% PF Block % SWG5 gray 598 90.0 0.272 83.6 60.7 22.9 1.377 27.4 SWG5 brown 502 89.1 0.232 86.5 64.3 22.2 1.345 25.7 NKT5 gray 590 94.1 0.498 86.9 51.0 35.9 1.704 41.3 NKT5 brown 580 95.3 0.385 88.0 55.9 32.1 1.574 36.5 RDP5 gray 596 94.0 0.234 84.5 61.5 23.0 1.374 27.2 RDP5 brown 572 94.6 0.219 85.2 62.0 23.2 1.374 27.2 CVS5 gray 610 88.0 0.231 80.4 61.0 19.4 1.318 24.1 CVS5 brown 601 94.3 0.197 85.0 60.8 24.2 1.398 28.5 JAP5 gray 587 93.7 0.345 88.1 59.4 28.7 1.483 32.6 JAP5 brown 484 80.3 0.176 83.3 68.4 14.9 1.218 17.9 DMP5 gray 591 96.4 0.332 88.1 59.7 28.4 1.476 32.2 DMP5 brown 584 95.2 0.226 88.1 64.1 24.0 1.374 27.2 DMT5 gray 596 93.6 0.631 86.2 41.6 44.6 2.072 51.7 DMT5 brown 570 94.3 0.565 88.2 47.9 40.3 1.841 45.7 DMT6 gray 593 93.7 0.586 85.3 42.3 43.0 2.017 50.4 DMT6 brown 569 93.4 0.534 85.7 48.3 37.4 1.774 43.6 CMT6 gray 597 94.7 0.691 86.2 37.6 48.6 2.293 56.4 CMT6 brown 442 93.3 0.747 88.2 44.2 44.0 1.995 49.9 TOA5 gray 583 89.4 0.557 84.2 48.5 35.7 1.736 42.4 YJG6 gray 596 91.3 0.348 85.9 57.6 28.3 1.491 32.9 YJG6 brown 444 92.5 0.301 89.0 65.0 24.0 1.369 27.0 OTS6 gray 579 92.2 0.482 84.2 51.9 32.3 1.622 38.4 OTS6 brown 582 92.0 0.290 84.3 60.5 23.8 1.393 28.2 HYS5 gray 595 91.5 0.685 85.3 39.4 45.9 2.165 53.8 HYS5 brown 462 89.7 0.614 86.5 45.9 40.6 1.885 46.9 HYS6 gray 598 91.8 0.630 84.2 40.7 43.5 2.069 51.7 HYS6 brown 577 93.3 0.535 86.4 47.2 39.2 1.831 45.4 CZP5 gray 582 93.4 0.609 86.1 46.9 39.2 1.836 45.5 CZP5 brown 575 93.0 0.407 86.4 54.3 32.1 1.591 37.2 CZP6 gray 586 92.3 0.410 84.9 55.8 29.1 1.522 34.3 CZP6 brown 584 91.8 0.254 84.9 63.6 21.3 1.335 25.1 SMS5 gray 597 92.2 0.611 85.1 40.9 44.2 2.081 51.9 SMS5 brown 568 92.6 0.624 86.4 45.1 41.3 1.916 47.8 SMS6 gray 599 90.9 0.669 83.8 37.8 46.0 2.217 54.9 SMS6 brown 570 90.7 0.568 84.5 46.4 38.1 1.821 45.1 Glass gray 643 98.5 0.213 92.4 57.0 35.4 1.621 38.3 Mean±SD 92.4 ±3.0 0.442 ±0.177 85.9 ±2.1 52.6 ±9.0 33.2 ±9.2 1.681 ±0.300 ΔOD:ΔT%=0.940, ΔOD:PF=0.940, ΔT%:PF=0.981, ΔT%:Block%=0.997, Block%:PF=0.989, r Block%: ΔOD=0.951 (p<0.001 for all paired t-test) The first two characters mean initials of company names and the next one character indicates initials of brand names, a digit number indicate 5 for middle index and 6 for high index, the next words show colors of photochromic lenses. Photochromic factor was calculated as ratio of the colorless state to the colored state in transmittances. SD: standard deviation, λ max : wavelength of maximum absorbance, T max : maximum transmittance at λ max, ΔOD: change of optical density, ΔT%: difference between colorless and colored state, Block %: optical blocking % ratio of ΔT% to colorless state T%. r: Pearson s correlation coefficient. 38.7 ±10.6
26 Dong-Sik Yu, Hyun Gug Cho, and Byeong-Yeon Moon 장 (λ max ) 기준의반감기 (t λ1/2 ) 와 380~780 nm의평균흡광도 [14] 를기준한반감기 (t m1/2 ) 로결정하였다. 3) 자료분석자료분석은 SPSS(Ver.21 for window) 를이용하여기술통계, 평균비교및상관관계분석을실시하였다. 모든분석에서신뢰구간은 95% 하였고유의확률 (p)<0.05일때통계적으로유의한차이를보이는것으로판단하였다. 결과및고찰 1. 광변색렌즈의광학적성능 14개사 36개제품의광변색렌즈에대한광학적변화의특성은 Table 2와같다. λ max 는가시광선영역 (380~780 nm) 에서변색전과후의투과율차이가최대값인파장을말하며, λ max 가 2개이상인경우단파장으로결정하였고변곡이일어나는지점으로하였다. λ max 에서최고의투과율을 T max 라하였다. 본연구에서변색렌즈테스터기에의한활성화된유색상태의투과율은 380~780 nm에서 37.6%~68.4%, λ max 에서 5.5%~40.0% 이다. 이는 Renzi-Hammond 등 [15] 의광변색렌즈가시각에미치는영향연구에서크세논 (xenon) 광을이용하여활성화된유색상태의투과율 63%~71% 보다낮다. 이러한낮은투과율은광변색렌즈의퇴색속도평가시높은활성화상태에서평가되었다는의미이다. 그러나조사대상에대한광변색렌즈의활성된상태, 즉정상상태투과율 (steady state transmittance) 는본연구에서확인하지않았다. 무색과유색상태의투과율은가시광선영역의평균투과율이며, 이들두투과율차이를 ΔT% 라하였으며이는변색의폭이크다는의미이다. 광밀도변화 (change in optical density, ΔOD) [16] 는광변색후일정한시간의경과에서투과율의변화를 ΔOD=log 10 (colorless state T%) -log 10 (colored state T%) 로나타낸다. ΔOD가높을수록색의밀도가높은것으로유색상태와무색상태의차이가확실하여명확한변색효과를볼수있다는의미로해석된다. 광변색인자 (photochromic factor, PF) [17] 는유색상태대한무색상태의투과율의비율을말하며, 광변색반응의동적범위 (dynamic range of photochromic reaction) 를나타낸다. PF는광밀도와유사하나시간경과에따른변화를고려하지않은차이점을갖고있다. 광변색렌즈의선글라스기능으로서광차단율 (block %) 은무색상태의투과율에대한가시광선영역에서광차단율 (ΔT%) 을나타낸것이다. 평가대상의광변색렌즈는 λ max 가 442~610 nm에서나타났으며회색에서 543~610 nm, 갈색에서 442~601 nm였 다. OTS6 gray와 OTS6 brown를제외하고동일사제품에서회색이갈색광변색렌즈보다긴파장을보였다. 이는 Yu 등 [18] 이플로우코팅 (flow coating) 으로제조한황색, 적색과검정색광변색렌즈에서 λ max 가각각 416 nm, 490 nm, 593 nm인것과유사한경향을보였다. T max 는 80.3(JAP5 brown)~98.5%(glass gray) 로나타났다. ΔOD는 0.176(JAP5 brown)~0.747(cmt6 brown) 이며, Yu 등 [18] 의플로우코팅 (flow coating) 의광변색렌즈에서의 ΔOD가 0.051~0.237인것보다크다. 유색과무색의투과율차이를나타내는 ΔT% 는 14.9(JAP5 brown)~48.6%(cmt6 gray) 였으며, PF 는 1.218(JAP5 brown)~2.293(cmt6 gray), 차단율은 17.9% (JAP5 brown)~56.4%(jap5 brown) 였다. ΔOD, ΔT%, PF 및 block % 간의상관관계에서 r=0.940(δod:δt%)~0.997 (ΔT%:block %) 로높게나타났다 ( p<0.001). 상관관계분석에서변색의차이를보여주는 ΔT% 항목과선글라스기능으로서차단율보여주는 block % 항목이광변색렌즈의특성을잘나타내었다. 이러한측면에서광변색렌즈의특성은 CMT6 gray와 SMS6 gray에서잘나타났다. 2. 광변색렌즈의퇴색속도평가가시광선영역의퇴색속도는평균투과율 [14,19] 과시감투과율 (luminous transmittance) [20] 로기준하여평가할수있다. 시감투과율에의한변색속도평가는시감효율함수와표준광 D65의분광분포를고려해야하므로변색렌즈의색상에따라가중치가다르다. 이와달리평균투과율에의한평가는가중치없이보다간단하고신속하게변색속도를평가할수있다. 본연구에서는광변색렌즈의퇴색속도를 λ max 기준으로한반감기 (t λ1/2 ) 와가시광선영역의평균투과율기준으로한반감기 (t m1/2 ) 이다. λ max 기준으로한방법은 Keum 등 [21] 이 spiropyran 광변색물질의퇴색속도를최대흡광도의변화를측정하고자연로그함수의농도와시간함수로부터 1차속도상수를계산하여구하는방법과같다. 평균투과율기준의방법은 λ max 대신가시광선영역전체에걸쳐광변색의특성을나타내는장점을갖는다. 이와같은방법으로조사대상의광변색렌즈의반감기평가결과는 Table 3 과같다. t λ1/2 은 45(CZP6 brown)~195 sec(swg5 gray), t m1/2 은 44(HYS5 brown)~217 sec(swg5 gray) 로 t λ1/2 보다 t m1/2 가넓은범위의분포도를보였다. 이러한분포의차이는 t λ1/2 의경우단일파장을반영한것이며, t m1/2 은가시영역전체를반영한것으로투과율 ( 흡수도 ) 의차이에서나타난결과로생각한다. 또한단일파장에서는 λ max 의위치에따라측정시간의시차를고려하지않은점이다. 앞으로이에관한추가적인연구가필요하다.
Evaluation of Fading Rate of Photochromic Lenses in Domestic Market 27 Table 3. Fading rate of photochromic lenses according to measurement criteria k λ, 10 3 t λ1/2, sec R 2 k m, 10 3 t m1/2, sec R 2 sec (min/sec) Photochromic lens λ max criterion Mean transmittance criterion T 80% SWG5 gray 3.546 195 0.801 3.193 217 0.851 695 (11 35 ) SWG5 brown 3.649 190 0.859 3.882 179 0.870 2344 (39 40 ) NKT5 gray 9.900 70 0.963 9.467 73 0.972 222 (3 42 ) NKT5 brown 8.722 79 0.944 8.155 85 0.946 224 (3 44 ) RDP5 gray 6.054 114 0.934 5.670 122 0.930 207 (3 27 ) RDP5 brown 4.958 140 0.914 4.716 147 0.887 232 (3 52 ) CVS5 gray 5.904 117 0.898 4.555 152 0.914 387 (6 27 ) CVS5 brown 5.105 136 0.850 4.382 158 0.874 155 (2 35 ) JAP5 gray 6.713 103 0.948 6.571 105 0.960 254 (4 1 4 ) JAP5 brown 7.579 91 0.871 7.744 90 0.870 3523 (58 43 ) DMP5 gray 7.500 92 0.961 6.618 105 0.941 181 (3 01 ) DMP5 brown 8.543 81 0.958 5.789 120 0.867 146 (2 26 ) DMT5 gray 8.459 82 0.986 8.169 85 0.993 253 (4 13 ) DMT5 brown 8.338 83 0.986 7.907 88 0.993 270 (4 30 ) DMT6 gray 8.495 82 0.995 8.401 83 0.999 262 (4 22 ) DMT6 brown 9.993 69 0.986 9.984 69 0.995 225 (3 45 ) CMT6 gray 4.692 148 0.995 4.216 164 0.998 272 (4 32 ) CMT6 brown 6.136 113 0.997 5.426 128 0.999 263 (4 23 ) TOA5 gray 7.771 89 0.975 8.658 80 0.999 209 (3 29 ) YJG6 gray 5.489 126 0.946 5.203 133 0.955 191 (3 11 ) YJG6 brown 4.036 172 0.959 4.633 150 0.980 572 (9 32 ) OTS6 gray 10.677 65 0.984 10.695 65 0.991 162 (2 42 ) OTS6 brown 12.168 57 0.989 9.391 74 0.936 127 (2 07 ) HYS5 gray 9.176 76 0.996 9.019 77 1.000 265 (4 25 ) HYS5 brown 11.162 62 0.998 15.616 44 0.900 275 (4 35 ) HYS6 gray 9.390 74 0.988 9.122 76 0.994 251 (4 11 ) HYS6 brown 9.818 71 0.993 9.630 72 0.999 228 (3 48 ) CZP5 gray 8.600 81 0.986 7.916 88 0.986 160 (2 40 ) CZP5 brown 8.500 82 0.976 7.090 98 0.952 138 (2 18 ) CZP6 gray 11.016 63 0.960 10.705 65 0.962 168 (2 48 ) CZP6 brown 15.414 45 0.999 10.257 68 0.914 137 (2 17 ) SMS5 gray 4.659 149 0.981 4.300 161 0.988 257 (4 17 ) SMS5 brown 5.704 122 0.997 5.198 133 1.000 211 (3 31 ) SMS6 gray 5.360 129 0.997 4.925 141 0.999 261 (4 21 ) SMS6 brown 7.517 92 0.994 7.035 99 0.998 213 (3 33 ) Glass gray 5.245 132 0.905 4.227 164 0.894 233 (3 53 ) The first two characters mean initials of company names and the next one character indicates initials of brand names, a digit number indicate 5 for middle index and 6 for high index, the next words show colors of photochromic lenses. Fading time until the 80% transmittance at λ max is reached. λ max : wavelength of maximum absorbance, k λ and k m : fading rate constant for each criterion, t λ1/2 and t m1/2 : half-life time ln2/ k for each criterion, R 2 : coefficient of determination.
28 Dong-Sik Yu, Hyun Gug Cho, and Byeong-Yeon Moon Fig. 1. Determination of rate constant from linear regression of fading time (0, 120, 240, 360 sec) versus absorbance (SWG5 gray: an example with relative low R 2 =0.801 coefficient of determination, CZP6 brown: another example with relative high R 2 =0.999 coefficient of determination). 한편, 반감기는특정시간과흡수도 ( 투과율에서변환 ) 관계의선형회귀식 (linear regression equation) 으로부터속도상수를결정하여구한다. Fig. 1은반감기결정과정의한예이다. 여기서결정계수 (R 2 ) 는상관계수 (r) 의제곱으로결정계수가높은것은퇴색과정이 1차속도식에잘맞는것으로반감기의신뢰도가높다는의미이다. R 2 가 t λ1/2 에서 0.801(SWG gray)~0.999(czp6 brown) 이고, t λ1/2 에서 0.851(SWG gray)~1.000(hys5 gray, SMS5 brown) 로나타났다. 또한, 광변색렌즈의퇴색과정에서일정시간경과후의무색상태를 λ max 에서투과율이 80% 까지이르기까지의시간 (T 80% ) 으로측정하였다. 짧게는 JAP5 brown에서 127 sec(2 07 ) 부터길게는 JAP5 brown에서 3,523 sec(58 43 ) 까지다양하였다. 위결과에서보듯이반감기와 T 80% 는광변색렌즈에따라차이를보였다. 이러한퇴색속도에영향을주는요인을분석한결과는 Table 4와같다. 두반감기 t λ1/2 과 t m1/2 의평균은각각 102±37 sec와 110±40 sec 유의한차이를보였다 (paired t-test, p=0.001). 굴절률이나색상에따른차이는 t λ1/2 과 t m1/2 에서유의하지않았으나 (student s t-test, t λ1/2 : p=0.783과 0.619, t m1/2 : p=0.574와 0.619), T 80% 에서고굴절이중굴절렌즈보다더짧은시간으로유의성을보였고 (student s t-test, p=0.034), 회색렌즈가갈색렌즈보다빨랐다 (student s t-test, p=0.005). 제조방법에따른차이는 t λ1/2 과 t m1/2 에서모두유의하였고 ( 모두 Table 4. Comparative statistical data of factors influencing on fading rate Index Color Manufacture Process Total (N=36) t λ1/2, sec t m1/2, sec T 80%, sec r Middle 108±37 117±42 493±819 High 93±38 99±36 238±108 Student's t-test p=0.783 (t=1.118) p=0.619 (t=1.302) p=0.034 (t=1.152) Gray 105±35 113±43 257±118 Brown 99±41 106±38 546±928 Student's t-test p=0.574 (t=0.432) p=0.524 (t=0.549) p=0.005 (t = 1.346) Casting 130±37 a 142±35 a 702±1038 Imbibition 91±25 b 95±31 b 244±24 Coating 83±30 c 90±33 c 394±550 one-way ANOVA Paired t-test p=0.001 F(2,33)=8.089 a > b c p=0.001 F(2,33)=9.359 a > b > c 102±37 110±40 p=0.001 (t = 3.653) p=0.098 F(2,33)=2.490 394±650 t λ1/2 : t m1/2 = 0.946(p=0.000) t m1/2 : T 80% = 0.175 (p=0.308) t λ1/2 : T 80% = 0.277 (p=0.102) Data are mean±standard deviation (SD). p-values of less than 0.05 indicate statistically significant correlations. The results of Bonferroni Post-hoc. Fading time until the 80% transmittance at λ max is reached. t λ1/2 and t m1/2 : half-life time ln2/k for each criterion, r: Pearson s correlation coefficient.
Evaluation of Fading Rate of Photochromic Lenses in Domestic Market 29 Table 5. Comparison of fading rate among photochromic lenses Fast t λ1/2, sec Photochromic lens Factor t m1/2, sec Photochromic lens Factor T 80% Photochromic lens Factor 45 CZP6 brown co h b 44 HYS5 brown co m b 127 OTS6 brown co h b 57 OTS6 brown co h b 65 CZP6 gray co h g 137 CZP6 brown co h b 62 HYS5 brown co m b 65 OTS6 gray co h g 138 CZP5 brown co m b 63 CZP6 gray co h g 68 CZP6 brown co h b 146 DMP5 brown ca m b 65 OTS6 gray co h g 69 DMT6 brown im h b 155 CVS5 brown ca h b 148 CMT6 gray im h g 161 SMS5 gray co m g 387 CVS5 gray ca m g 149 SMS5 gray co m g 164 Glass gray ca m g 572 YJG6 brown ca h b Slow 172 YJG6 brown ca h b 164 CMT6 gray im h g 695 SWG5 gray ca m g 190 SWG5 brown ca m b 179 SWG5 brown ca m b 2344 SWG5 brown ca m b 195 SWG5 gray ca m g 217 SWG5 gray ca m g 3523 JAP5 brown ca m b The first two characters mean initials of company names and the next one character indicates initials of brand names, a digit number indicate 5 for middle index and 6 for high index, the next words show colors of photochromic lenses. Fading time until the 80% transmittance at λ max is reached. t λ1/2 and t m1/2 : half-life time ln2/k for each criterion, co: coating, im: imbibition, ca: casting, m: middle index, h: high index, b: brown color, g: gray color. one-way ANOVA, p=0.001) 사후분석에서 t λ1/2 은코팅법과침투법이캐스팅법보다짧았으며, t m1/2 은코팅법, 침투법, 캐스팅법순으로반감기가짧았다. T 80% 에서제조방법에따른차이는나타나지않았다 (one-way ANOVA, p=0.098). t λ1/2, t m1/2 과 T 80% 의상관관계에서 t λ1/2 과 t m1/2 에서상관관계 (r) 가 0.946(p=0.000) 으로높았으나그외에서상관관계는 유의하지않았다 (t m1/2 : T 80% =0.175, p=0.308; t λ1/2 : T 80% =0.277, p=0.102). 이러한상관관계로부터반감기가짧을수록투과율 80% 까지도달하는시간도짧다고볼수없다. 한편, Ouyang 등 [17] 은광변색렌즈성능평가에미치는요인을기하학적구조에두고평가한결과, 렌즈의커브는투과율에영향이없고, 두께의경우 1.8 mm 이상에서최소의영향을갖지만광변색속도에영향을주지않은것으로보고하였다. 광변색렌즈 36개제품중에서두반감기와 T 80% 에서각각의퇴색속도가빠른것 5개제품과느린것 5개제품을선정하고그요인을분석한결과는 Table 5와 Fig. 2와같다. t λ1/2 은코팅법, 고굴절에서빨랐고, 캐스팅법에서느린경향을보였다. t m1/2 은코팅법과고굴절에서빨랐고, 중굴절과회색에서느린경향을보였다. T 80% 에서코팅법과갈색에서빨랐고, 캐스팅법, 중굴절에서느린경향을보였다. CZP6 brown와 OTS6 brown이퇴색속도빨랐고, SWG5 gray과 SWG5 brown가속도가느렸다. Klukowska 등 [22] 은코팅법에의해제조한광변색물질의반감기속도는코팅에사용된하이브리드 (hybrid) 의구조, 즉광변색물질의유동성 (mobility) 이클수록빠르다고하였다. 이러한해석은광변색물질의구조, 제조방법, 굴절률에따른변색속도의변화에적용할수있을것이다. 이를적용하면광변 Fig. 2. Photochromic lenses with fast (top 5 lenses) or slow (bottom 5 lenses) fading rate. 색렌즈의퇴색속도는코팅법, 침투법, 캐스팅법의순으로빠른이유를설명할수가있으나제품별개별분석에서고굴절광변색렌즈가중굴절보다빠른이유는설명되지않는다. 그러나앞서전체분석의결과에서반감기준한퇴색속도는굴절률과무관한것으로확인되었고, 또한렌즈재질내의침투법과캐스팅법보다표면위의코팅된광변색렌즈의퇴색속도가굴절률과무관하게대부분빠르게나타났다. 결 론 국내유통되는광변색렌즈를중심으로광학적성능을분석한결과로부터유색과무색상태의투과율을기준으로평가하는것보다선글라스기능과일반안경렌즈기능
30 Dong-Sik Yu, Hyun Gug Cho, and Byeong-Yeon Moon 을평가할수있는유색과무색상태의투과율차이 (ΔT%) 를기준으로평가하는것이바람직한것으로본다. 그이유는 ΔT% 가광밀도변화 (ΔOD), 유색상태에대한무색상태의투과율의비율로나타내는광변색인자 (PF) 및광차단율 (Block %) 과상관관계가높고광변색렌즈유통에서누구나쉽게알수있는요소이기때문이다. 반감기기준으로광변색렌즈의퇴색속도를평가한결과는코팅법이침투법과캐스팅법보다빨랐고, 굴절률, 색상에따른차이는없었다. 개별제품의퇴색속도를평가한결과는코팅법, 고굴절렌즈, 갈색의변색렌즈가빨랐고, 색상에관계없이캐스팅법이느렸다. 또한, 변색후무색상태를평가하는항목, 즉 λ max 에서투과율이 80% 에도달하는시간 (T 80% ) 은회색이갈색보다빠른것으로나타났다. 국내유통되고있는광변색렌즈의변색특성, 특히퇴색속도에서변동범위가넓었다. 이는제품에따라성능의차이가다양하다는의미이다. 따라서제조사들은유통과정에서광변색렌즈의특성, 즉유무색의투과율차이, 반감기및특정투과율에도달하는시간을표기하여렌즈취급자와소비자에게정확한정보를제공해야할것이다. 감사의글 2016년도강원대학교대학회계학술연구조성비로연구하였음 ( 관리번호-620160151). REFERENCES [1] Jalie M. Ophthalmic lenses and dispensing, 1st Ed. Oxford: Butterworth-Heinemann, 1999;90-93. [2] The Korea Optical News. Photochromic lens. 11 June 2015. http://www.opticnews.co.kr/news/articleview.html? idxno=25213(22 January 2017). [3] Crano JC, Flood T, Knowles D, Kumar A, Van Gemert B. Photochromic compounds: chemistry and application in ophthalmic lenses. Pure Appl Chem. 1996;68(7):1395-1398. [4] Fang Chen, Hallett Cove. Liquid casting compositions, production processes and photochromic optical elements. U.S. Patent 8576471, 2013. [5] Naour-Séné LL. Process of integrating a photochromic substance into an ophthalmic lens and a photochromic lens of organic material. U.S. Patent 4286957, 1981. [6] Sakagami T, Machida K, Fujii Y, Arakawa A, Murayama A. Photochromic lens. U.S. Patent 4756973, 1988. [7] Yu DS, Moon BY, Son JS. A comparative study of ophthalmic spectacle lenses standards. J Korean Ophthalmic Opt Soc. 2004;9(2):397-425. [8] Jeong JH, Sim SH. A study of optics and color difference of various photochromic lenses by UV lamp. Korean J Vis Sic. 2006;8(2):29-36. [9] Kim YG, Seong JS. Photochromic lens development to use nano particle (1): photochromic lens' estimation method and application. 2002; 7(2):169-174. [10] Yu DS. Evaluation of the fading rate of photochromic lenses by coating. Korean J. Vis. Sci. 2015;17(1):1-8. [11] Tivadar F, Bojana V. Organic nanoparticulate photochromes. Current Organic Chemistry. 2013;17(16):1771-1789. [12] Bouas-Laurent H, Dürr H. Organic photochromism. Pure Appl Chem. 2001;73(4):639-665. [13] Crano JC, Guglielmentti. Organic photochromic and thermochromic compounds volume 1: main photochromic families. New York: Kluwer Academic Publishers, 1999; 235-236. [14] Owczarek G, Gralewicz G, Skuza N, Jurowski P. Light transmission through intraocular lenses with or without yellow chromophore (blue light filter) and its potential influence on functional vision in everyday environmental conditions. Int J Occup Saf Ergon. 2016;22(1):66-70. [15] Renzi-Hammond LM, Hammond BR. The effects of photochromic lenses on visual performance. Clin Exp Optom. 2016;99(6):568-574. [16] Guo K, Chen Y. A strategy for the design of photochromic naphthopyrans with large optical density at photosteady state and fast fading speed at ambient temperature in the dark. J Mater Chem. 2010;20:4193-4197. [17] Ouyang L, Huang H, Tian Y, Peng W, Sun H, Jiang W. Factors affecting the measurement of photochromic lens performance. Coloration Technology. 2016;132(3):238-248. [18] Yu DS, Moon BY, Ha JW. Preparation and characteristics of photochromic plastic lenses by hard coatings. J Korea Academia-Industrial cooperation Society. 2009;10(7):1635-1641. [19] ANSI Z80.1-2015: Ophthalmics-prescription spectacle lenses-recommendations. [20] ISO 8980-3:2013 Ophthalmic optics-uncut finished spectacle lenses. part 3: transmittance specifications and test methods. [21] Keum SR, Hur MS, Kazmaier PM, Buncel E. Thermoand photochromic dyes: Indolino-benzospiropyrans. part 1. UV VIS spectroscopic studies of 1,3,3-spiro(2 H-1- benzopyran-2,2 -indolines) and the open-chain merocyanine forms; solvatochromism and medium effects on spiro ring formation. Can J Chem. 1991;69:1940-1947. [22] Klukowska A, Posset U, Schottner G, Jankowska-frydel A, Malatesta V. Photochromic sol-gel derived hybrid polymer coatings: the influence of matrix properties on kinetics and photodegradation. Materials Science-Poland. 2004;22(3): 187-199.
Evaluation of Fading Rate of Photochromic Lenses in Domestic Market 31 국내유통광변색렌즈의퇴색속도평가 유동식 *, 조현국, 문병연 강원대학교안경광학과, 삼척 25949 투고일 (2017 년 02 월 01 일 ), 수정일 (2017 년 02 월 20 일 ), 게재확정일 (2017 년 03 월 30 일 ) 목적 : 광변색렌즈의성능에영향을주는퇴색속도와요인들을평가하고자하였다. 방법 : 14 개회사로부터 36 개제품의국내유통광변색렌즈를수집하였고, 자외선조사로변색시킨후가시광선영역에서시간에따른투과율을측정하였다. 투과율은 UV/VIS 분광광도계로측정하였다. 퇴색속도는반감기 (t 1/2 ) 와투과율 80% 까지퇴색되는시간 (T 80% ) 으로평가하였다. 결과 : 광변색렌즈의성능은광밀도변화 (ΔOD), 광차단율 (block %) 보다투과율차이 (ΔT%) 에서더잘드러났다. t 1/2 에서코팅법이침투법과캐스팅법보다빨랐다 (one-way ANOVA, p=0.001). 광변색렌즈의 T 80% 은중굴절보다고굴절에서, 갈색보다회색에서유의하게빨랐다 (student s t-test, 각각 p=0.034, p=0.005). 그러나 T 80% 은 t 1/2 와상관관계는없었다. 광변색작용은 ΔT% 에서 14.9%~48.9%, t 1/2 에서 44 sec~217 sec, T 80% 에서 127sec(2 07 )~3,523 sec(58 43 ) 로다양하게나타났다. 결론 : 퇴색속도에근거한광변색렌즈의성능은각제품마다큰차이를보였다. 따라서제조사들은퇴색속도와관련된정확한광변색의정보 (ΔT%, t 1/2, T 80% ) 를소비자와취급자에게제공해야할것이다. 주제어 : 광변색렌즈, 퇴색속도, 반감기, 투과율, 국내시장