본 연구에서는 소프트콘택트렌즈에 의한 각막염 유발균인 포도상구균과 칸디다균의 흡착이 소프트콘택트렌즈 재질 특성 및 착색여부에 따라 달라지는 지를 분석하였으며 균 흡착에 영향을 미치는 눈물에 함유되어 있는 항균단백질의 작용이 렌즈 재질 특성 및 착색여부에 따라 달라지는 지를 분석하여 각막염 유발균에 대한 안전성에 영향을 미치는 요인을 알아보고자 하였다.
Etafilcon A, hilafilcon B, nelfilcon A 재질의 투명소프트콘택트렌즈(이하 투명렌즈)와 etafilcon A, 습윤제(PVP)를 포함한 etafilcon A, hilafilcon B, nelfilcon A 재질의 써클소프트콘택트렌즈(이하 써클렌즈)에 포도상구균, 칸디다균을 각각 흡착시켰다. 콘택트렌즈 착색부와 투명부의 비교, 투명부의 중심부와 주변부의 비교를 통하여 착색여부에 따른 균 흡착의 차이를 알아보았다. 또한, 24시간동안 인공눈물을 침착시킨 후의 콘택트렌즈에 흡착되는 균 수를 분석하였으며, 인공눈물의 항균단백질의 항균력 유지기간을 알아보기 위해 인공눈물이 침착된 콘택트렌즈를 PBS에서 7일, 14일, 28일 동안 진탕시킨 후 흡착균 수를 측정하였다. 콘택트렌즈에 침착된 단백질은 전기영동한 후 band의 진하기를 측정하여 분석하였다.
투명렌즈 재질별 균 흡착양은 포도상구균과 칸디다균 모두 etafilcon A > hilafilcon B > nelfilcon A 순으로 흡착되었으며, 써클렌즈 재질별 균의 흡착양은 etafilcon A > 습윤제가 함유된 etafilcon A > hilafilcon B > nelfilcon A 재질 순으로 많이 흡착되었다. 투명렌즈와 써클렌즈는 재질별 균 흡착량이 통계적으로 유의하였다.
투명렌즈와 써클렌즈에 포도상구균과 칸디다균은 etafilcon A 재질의 렌즈에서는 투명렌즈보다 써클렌즈에, hilafilcon B 및 nelfilcon A 재질의 렌즈에서는 투명렌즈에 더 많이 흡착되는 경향을 보였다. 투명렌즈와 써클렌즈의 균 흡착은 통계적으로 유의한 차이가 없었다.
써클렌즈의 착색여부에 따른 포도상구균과 칸디다균의 흡착은 4가지 재질 모두에서 착색부의 흡착양보다 투명부의 흡착양이 많았으며, 포도상구균은 통계적으로 유의한 차이가 있었지만, 칸디다균 흡착은 유의한 차이가 없었다. 써클렌즈의 투명부의 중심부와 주변부에 흡착된 포도상구균의 흡착양은 중심부보다 주변부의 흡착양이 많았으며, etafilcon A 재질의 렌즈만이 통계적으로 유의성이 있었다.
Etafilcon A 재질에 흡착된 단백질은 대부분 라이소자임임을 확인 할 수 있었으며 인공눈물이 침착된 기간이 길어질수록 단백질량이 감소하였는데 28일 경과하였을 때의 단백질양은 습윤제가 함유된 써클렌즈 > 투명렌즈 > 써클렌즈 순이었다. 또한 etafilcon A 재질의 렌즈에 흡착된 균 수는 인공눈물이 침착된 지 28일 경과 후가 되서야 인공눈물 침착전과 비슷해져 인공눈물의 항균력이 없어짐을 알 수 있었다. 균이 흡착된 양은 써클렌즈 > 투명렌즈 > 습윤제가 함유된 써클렌즈 순으로 많았다. Hilafilcon B 재질 렌즈에서는 인공눈물 침착 후 7일이 경과 후에 인공눈물의 항균력이 없어졌으며 균의 흡착양은 투명렌즈 > 써클렌즈, 침착된 단백질량은 써클렌즈> 투명렌즈로 나타났다. Nelfilcon A 재질의 렌즈에서는 14일 경과하였을 경우 인공눈물의 항균력이 없어졌으며, 균의 흡착양은 투명렌즈 > 써클렌즈, 침착단백질량은 써클렌즈 > 투명렌즈로 나타났다. 이상에서 렌즈에 침착된 눈물단백질의 양과 경과기간에 따른 항균력의 변화는 렌즈의 재질, 착색여부, 투명부의 위치에 따라 달랐으며, 흡착된 균 수에 영향을 미침을 알 수 있었다.
주사전자현미경을 통해 콘택트렌즈 표면과 균의 흡착 양상을 관찰하였을 때 샌드위치공법으로 착색된 etafilcon A 재질은 표면적으로는 매끈하게 보이나 착색되어 있는 부분에서의 흡착 균 수가 많은 것으로 나타났다. Hilafilcon B와 nelfilcon A 재질의 써클렌즈은 착색부분이 표면에 돌출되어 있어 투명부분과 거칠기에서 차이가 있었으며, 착색부분에 흡착된 균 수가 적음을 확인 할 수 있었다.
본 연구를 통해서 콘택트렌즈의 재질 및 착색여부, 투명부의 위치, 엣지디자인은 균의 흡착에 영향을 미치지만 재질 특성이 균의 흡착에 가장 많은 영향을 주는 것을 알 수 있었다. 또한, 눈물단백질의 침착에 따른 균 흡착량 차이도 재질 특성에 따라 달라지며, 항균단백질의 변성 정도는 재질 특성에 따라 달라짐을 알 수 있었다. 이에 따라 콘택트렌즈 재질 특성, 착색여부, 착색공법에 따라 콘택트렌즈 착용이 원인이 되는 세균성 염증의 발생비율이 달라질 수 있으며, 콘택트렌즈 관리방법에도 차이를 두어야 함을 제안한다.

This study was conducted to analyze whether adhesion of Staphylococcus aureus and Candida albicans, causative bacterial species of keratitis, by soft contact lens wear differs according to the characteristics of lens materials and pigmentation of soft contact lens. The factors affecting on the stability of causative bacterial species of keratitis were further investigated by analyzing whether the effect of antibacterial proteins contained in human tear, which affects bacterial adsorption differs according to the characteristics of lens materials and pigmentation of lens.
S. aureus and C. albicans were adsorbed, respectively, onto clear soft contact lenses made of etafilcon A, hilafilcon B and nelfilcon A (hereafter, clear lenses) and circle soft contact lenses (hereafter, circle lenses) made of etafilcon A, etafilcon A with a wetting agent (PVP), hilafilcon B and nelfilcon A. The difference of bacteria adhesion according to the pigmentation was investigated through a comparison between the pigmented and the non-pigmented areas of the contact lenses and a comparison between the central and the peripheral areas of the non-pigmented part. In addition, the number of bacteria adsorbed onto the contact lenses after the incubation with artificial tears for 24 hours was analyzed. The number of the adsorbed bacteria was also measured after further incubation of the contact lenses deposited with artificial tear in phosphate buffered saline for 7, 14 and 28 days to examine the time for keeping their antibacterial activity of antibacterial protein in artificial tears. The proteins deposition on the contact lenses were analyzed by estimating the density of electrophoretic bands.
The amount of bacterial adsorption by the materials of clear lenses was shown as the order of etafilcon A > hilafilcon B > nelfilcon A in both S. aureus and C. albicans, and the amount of bacterial adsorption by the materials of circle lenses was revealed as the order of etafilcon A > etafilcon A with a wetting agent > hilafilcon B > nelfilcon A. In the clear lenses and circle lenses, the difference in amount of bacterial adsorption by the lens materials was statistically significant.
S. aureus and C. albicans tended to be adsorbed more to circle lenses than to clear lenses in the lenses made of etafilcon A, while they were adsorbed more in clear lenses in the lenses made of hilafilcon B and nelfilcon A. However, there was no statistically significant difference in bacterial adsorption between clear lenses and circle lenses.
As for the adsorption of S. aureus and C. albicans according to the pigmentation of circle lenses, the adherent amount was more in the non-pigmented area than in the pigmented area in all four materials. There was a statistical significant difference in the adsorption of S. aureus, while there was no significant difference in the adsorption of C. albicans. The adherent amount of S. aureus onto the non-pigmented part of circle lenses was more in the peripheral area than in the central area, while there was a statistically significant difference only in the lens made with etafilcon A.
Lysozyme was identified as the protein mostly adsorbed onto etafilcon A lens. With the longer time after the deposition of artificial tears, the amount of proteins became less, and the amount of proteins was detected as the order of circle lens with a wetting agent > clear lens > circle lens when 28 days passed. In addition, the number of adherent bacteria onto the lens made of etafilcon A became similar to the number before the deposition of artificial tears just 28 days after the deposition of artificial tears, so it was found that the antibacterial activity of artificial tear disappeared. The amount of adherent bacteria was determined as the order of circle lens > clear lens > circle lens with a wetting agent. In the lenses made with hilafilcon B, it turned out that the antibacterial activity of artificial tears disappeared 7 days after the deposition of artificial tears and the amount of adherent bacteria was more in clear lens than in circle lens, while the amount of the deposited proteins was more in circle lens than in clear lens. In the lens made of nelfilcon A, it turned out that the antibacterial activity of artificial tears disappeared when 14 days passed, and the bacteria adsorption was higher in clear lens than in circle lens, while the amount of the deposited proteins was more in circle lens than in clear lens. From the results, it was found that the change of antibacterial activity, according to the amount of the tear protein deposited on the lens and the elapsed time was differed depending on the lens material, pigmentation and the position of the clear part, which affected the number of the adsorbed bacteria.
When the surface of the contact lens and the aspect of bacterial adsorption were observed by the scanning electron microscopy, the surface of etafilcon A pigmented by the sandwich process was smooth however, a lot of adsorbed bacteria in the pigmented part was observed. The pigmented area of circle lenses made of hilafilcon B and nelfilcon A had uneven surface, so the roughness was different from that in the non-pigmented area, and it was found that there were fewer bacteria adsorbed in the pigmented area.
From these results, it was found that the material characteristics had the greatest impact on bacterial adsorption though the materials and pigmentation of contact lens, the position of the non-pigmented area and edge design affected on bacteria adsorption. In addition, it was known that the difference in the amount of bacteria adsorption according to the deposition of tear protein varied depending the material characteristics, and the denaturation degree of antibacterial proteins also differed depending on the material characteristics. Accordingly, the incidence of the bacterial inflammation caused by contact lens wear may differ depending on the material characteristics, pigmentation and pigmentation method of the contact lenses, and thus, it is suggested that the contact lens caring method should be differentiated according to those properties.