Contact lenses are medical devices that are used in contact with eyeballs, and
they affect cornea significantly. With the recent increase in reduced visual
acuity due to long-term close range work and the use of computers/smart
phones, the usage of contact lenses has also increased. Accordingly, it has
induced many problems relevant to eye health such as dry eye syndrome. In
general, those with dry eyes need contact lenses with high wettability.
In this study, to develop materials for contact lenses with high wettability,
contact lenses using MPC(2-methacryloyloxyethyl phosphorylcholine) and
PEGMA(poly(ethylene glycol)methacrylate) monomers, which are biocompatible
and are expected to increase wettability, were manufactured, and the physical
properties were examined. Samples were manufactured by mixing
2-hydroxyethyl methacrylate(HEMA), which is a basic monomer for hydrogel
contact lenses, with MPC, PEGMA, and Styrene, and by copolymerizing them.
For the samples, nine types were utilized: eight types of contact lenses that
were manufactured depending on the ratio of constituent monomers and one
omafilcon A hydrogel contact lens, which contains MPC and is widely known to
have high wettability and which is available on the market. For comparison to a
case with a low moisture content, samples that mixed HEMA with MPC and
PEGMA and samples that mixed HEMA and styrene with MPC and PEGMA were used. To evaluate the physical properties of the copolymerized samples,
moisture content, refractive index, contact angle, and tensile strength were
measured.
As for the moisture content, the HMP sample that mixed HEMA with MPC
and PEGMA had the highest value, and the HS sample containing styrene and
PEGMA had the lowest value, compared to the contact lens made of HEMA.
As for the refractive index, HS and HSP had high values, while HM and HMP
had low values. The refractive index and the moisture content were found to
have an inversely proportional relationship. In the case of the tensile strength,
omafilcon A had an extremely low value, and HS had the highest value. As the
moisture content increased, the tensile strength showed a decreasing trend,
indicating that they have a close relationship. In the case of the contact angle,
HMP had the lowest value indicating high wettability, and HSMP had the
highest value indicating low wettability. Also, the contact angle of omafilcon A
was similar to that of HSMP. Therefore, it was found that omafilcon A had a
considerably high contact angle compared to the eight types of samples used in
this study. In addition, compared to basic MEMA, the samples containing MPC
had high moisture content and low refractive index, contact angle, and tensile
strength; and when PEGMA was added, the moisture content and refractive
index showed almost no change, but the contact angle and tensile strength
decreased. When MPC and PEGMA were mixed together, the highest moisture
content and the lowest contact angle could be obtained. Based on the above
results, it was found that the introduction of MPC and PEGMA monomers could
improve the wettability of hydrogel contact lenses.