Standardization of Wettability Evaluation for Ophthalmic Hydrogel Lenses

안의료용 하이드로겔 렌즈의 습윤성 평가에 관한 표준화

본 연구는 콘택트렌즈의 물리적 특성 중 하나인 습윤성의 표준화 규격에 대한 필요성 평가하는 것을 목적으로 하였다. 렌즈의 습윤성에 대한 표준규격의 필요성을 분석하기 위해 기본 하이드로젤 콘택트렌즈 재료에 습윤성 정도가 다른 물질들을 첨가하여 제조된 콘택트렌즈의 물성을 비교하였다. 렌즈제조를 위해 기본적인 모노머인 HEMA (2-hydroxyethyl methacrylate)와 교차결합제인 ethylene glycol dimethacrylate (EGDMA), 개시제인 azobisisobutyronitrile (AIBN), 그리고 친수성 물질로 알려진 N-vinyl-2-pyrrolidone (NVP), methacrylic acid (MA)와 소수성 물질로 알려진 methyl methacrylate (MMA), butyl methacrylate (BMA)를 각각 첨가하여 공중합 하였다. 또한 제조된 콘택트렌즈의 기본 물성을 평가하기 위해 굴절률, 함수율, 접촉각, AFM 및 분광 투과율을 측정하였다. 본 연구의 결과, 함수율의 경우 REF에 비해 MMA와 BMA를 첨가한 하이드로젤렌즈는 각각 약 14%, 27% 감소하였고, NVP와 MA를 첨가한 하이드로젤렌즈는 각각 약 5%, 28% 증가하였다. 습윤성의 경우 REF에 비해 MMA와 BMA를 첨가한 하이드로젤렌즈는 약 6%감소하였고 NVP와 MA를 첨가한 하이드로젤렌즈는 각각 1%, 23%로 증가하는 것으로 나타나 MA를 첨가한 하이드로젤렌즈를 제외하고는 변화가 미미한 것으로 나타났다. 습윤성은 콘택트렌즈 착용감에 영향을 주는 중요한 요소이지만 현재 정확하게 표준화된 규격이 없는 상태이다. 또한 표준화규격에 있는 함수율의 결과와 습윤성의 결과는 비례하지 않는 것으로 나타났으므로, 습윤성을 표준화시켜 정확한 성능 평가를 위해 규격 제정이 필요하다고 판단된다.

The purpose of this study was to analyze the need for standardization of wettability, which is one of the physical properties of contact lenses. This study compared the physical properties of lenses fabricated by adding materials with different wettability levels to basic hydrogel materials to analyze the necessity of standardized specifications for the wettability of lenses. To fabricate lenses, HEMA (2-hydroxyethyl methacrylate), ethylene glycol dimethacrylate (EGDMA, a crosslinking agent), and azobisisobutyronitrile (AIBN, an initiator) were copolymerized by adding N-vinyl-2-pyrrolidone (NVP) and methacrylic acid (MA), which are known as hydrophilic substances, as well as methyl methacrylate (MMA) and butyl methacrylate (BMA), which are known as hydrophobic substances. The refractive index, water content, contact angle, atomic force microscope (AFM), and spectral transmittance were measured to evaluate the basic properties of the fabricated lenses. The results showed that the water content of the hydrogel lens with MMA and BMA decreased by 14 and 27%, respectively, and the water content of the hydrogel lens with NVP and MA increased by about 5 and 28%, respectively, compared to REF. In the case of wettability, that of the hydrogel lens with MMA and BMA decreased by about 6%, and that of the hydrogel lens with NVP and MA increased by 1 and 23%, respectively, compared to REF. Except for the hydrogel lens with MA added, the changes were minimal. Wettability is a major factor affecting the wearing comfort of contact lenses, but there are currently no standardized specifications for it. In addition, the result of the water content in the standardized specifications was not proportional to the wettability result. Therefore, it is necessary to accurately evaluate the performance of the contact lens by standardizing the wettability measurement method.