Journal of Biomaterials and Nanobiotechnology, 2013, 4, 309-315
http://dx.doi.org/10.4236/jbnb.2013.44039 Published Online October 2013 (http://www.scirp.org/journal/jbnb) 309
Physical Properties of Ophthalmic Copolymers Containing
Vinylaniline and ZnO Nanoparticles*
A-Young Sung1#, Tae-Hun Kim2
1Department of Ophthalmic Optics, Sehan University, Jeonnam, South Korea; 2Department of Visual Optics, Baekseok University,
Chonan, South Korea.
Received May 25th, 2013; revised June 26th, 2013; accepted July 15th, 2013
Copyright © 2013 A-Young Sung, Tae-Hun Kim. This is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
The mixture of vinylanilin e and 2-h yd roxyeth yl mrthacrylate mix ed accord ing to the mixing ratio, was allowed to stir in
order to add functio nality. ZnO nanoparticles, dispersed for approximately 1 hr in an ultrasonic bench top cleaner, were
added to the mixture of monomers. Then the mixture at a mould was thermally polymerized to prepare high-perform-
ance hydrogel ophthalmic lens. The produced ophthalmic hydrogel lens was then put in 0.9% NaCl (normal saline solu-
tion) for 24 hrs for hydration, and various measurements were carried out. The surface analysis of ZnO nanoparticles
dispersed in the macromolecular polymer was conducted using AFM (XE-100, Parks System). The produced hydrogel
lens generally exhibited yellowish color, transparent and hydrophilic characteristics. Also, the contact lenses hydrated in
standard saline solu tion generally exhibited the ch aracteristics of flexibility and softness. The physical prop erties of the
ophthalmic hydrogel lens material were measured. The refractive indexes of 1.359 - 1.423, water content of 37% - 43%,
and visible transmittance of 74% - 82% were obtained.
Keywords: ZnO Nanoparticles; Vinylaniline; Spectral Transmittances; Contact Angles
1. Introduction
Recently, there has been active research on not only ba-
sic properties such as water content, wettability and ten-
sile strength, but also on functional properties such as
high oxygen permeability, antimicrobial quality and UV
protection, etc., in the study of contact lens materials
[1-6]. Research on the antimicrobial quality of contact
lens materials is booming, with an emphasis on nanopar-
ticles that are very widely applied in the industrial and
medicine areas [7-9]. As nano-composite materials have
unique electrical, magnetic, optical and engineering ap-
plicability due to their size-effect and quantum confine-
ment effect, they are being extensively studied in vari-
ous fields. Currently, research of applyi ng nano-composite
material to contact lenses is placing a disproportionate
emphasis on how to apply nano-silver and nano-gold for
antimicrobial quality. The optical features of nano-com-
posites, however, are one of the crucial characteristics
that have recently been brought into spotlight. The ultra-
violet blocking ability of contact lenses is recently in the
center of attention and is one of the very important opti-
cal properties. Ultraviolet rays can result in damage to
the cornea, the retina and the eye lens. Also, the dam-
age to the eye lens may cause cataracts and photic macu-
lopathy [10]. In regards to this, Duker-Elder [11], Zig-
man [12] and others revealed their research results
through animal tests under UV-B 280 - 320 nm, which
demonstrated that ultraviolet rays could cause eye lens
opacity. Various types of damage to cornea as well as the
eye lens can lead to degeneration. And if the damage is
acute, it can lead to keratitis [13-15]. Therefore, the sig-
nificance of ultraviolet reduction through contact lenses
is becoming more and more important. Research on ul-
traviolet blocking contact lenses revolved around benzo-
phenone-group substances, but recently it has been ex-
tended to other materials such as vinyl pyridine and vi-
nylanisole [16,17]. In addition, there has been research
on contact lens materials that are able to block not only
ultraviolet rays, but also infrared rays by using nano-
composites such as silicon 2,3-naphthalocyanine bis(tri-
hexylsilyloxide) and silicon 2,9,16,23-tetra-tert-butyl-
*This research was financially supported by Ministry of Trade, Industry
& Energy (MOTIE) and Korea Evaluation Institute of Industrial Tech-
nology (KEIT) through the Project of Standard Technology Develop-
ment.
#Corresponding author.

Physical Properties of Ophthalmic Copolymers Containing Vinylaniline and ZnO Nanoparticles 310
29H31H-p ht halocyanine dihy dr o xy de [1 8] .
ZnO nanoparticles have a strong luminescence prop-
erty in the ultraviolet region due to the broadband gap
energy and high excitation binding energy at room tem-
perature. Hence, it is used for semiconducting, piezo-
electric, photoconducting, and other applications and is
widely applied to disp lay screens using optical prop erties,
the electrodes of photocells, light-emitting diodes, laser
diodes, photovoltaic devices, etc. For that reason, while
ZnO nanoparticles are regarded as an important material
for the future, it has not yet been applied as a contact lens
material.
In this research, contact lenses were polymerized by
using ZnO nanoparticles. The physical and optical char-
acteristics of these lenses were then examined. If a pale
pigment is added to a contact lens material, it helps to
distinguish the lenses better than transparent ones and
can be used for a wider variety of applications. Therefore,
4-vinylanilin e, which is used in the d ye comp osition , was
added to mixture as an additive to analyze its properties.
2. Experiments and Methods
2.1. Reagents and Materials
HEMA (2-hydroxyethyl methacrylate), which was the
main material of hydrophilic hydrogel lenses used in the
test, and AIBN (azobisisobutyronitrile), an initiator used
for polymerization, were purchased from JUNSEI. NVP
(n-vinylpyrrolidone) and EGDMA (ethylene glycol di-
methacrylate) were purchased from Acros whereas
MMA (methyl methacrylate) was purchased f rom Crown
Guaranteed Reagents. 4-Vinylaniline and ZnO (nano-
powder, 100 nm particle size) were purchased from Al-
drich.
2.2. Polymerization
For the polymerization of the contact lens materials,
HEMA, NVP, MMA, EGDMA were employed as the
basic combination after purification. The procedure in-
volved washing an aqueous solution of monomer with
hexanes, salting the monomer by addition of NaCl, dry-
ing and distilling under reduced pressure. AIBN was
used as the initiator. ZnO nanoparticles were added to the
basic combination in certain proportions, and 4-viny-
laniline was proportion ally added to each combination to
be agitated for about 30 minutes. ZnO nanoparticles were
added to the basically combined monomers and dispersed
before being polymerized in an ultrasonic benchtop
cleaner (Branson 2510) for about an hour.
The polymerization of the contact lens material was
conducted through thermal polymerization in 70˚C for
about 40 minutes and in 80˚C for about 40 minutes.
Lastly, it was sent for heat treatment in 100˚C for about
40 minutes. To produce contact lenses, a cast mould-
method was used. The produced contact lenses samples
underwent the pre-process by being hydrated in 0.9%
NaCl saline for 24 hours. Afterward, their physical and
optical properties were measured.
The samples used in the test were named VA-1, VA-2,
VA-3, VA-4, and VA-5, depend ing on the 4-vinylaniline
content. Combinations that contained ZnO nanoparticles
were designated by adding Z to their names. Table 1
summarizes the combination rates of the contact lens
samples used in the test.
2.3. Instruments and Analysis
All contact lens samples used in the test were stored in
standard saline (0.9% NaCl saline) for at least 24 hours,
and then were kept at the test temperature (room tem-
perature) for at least 2 hours to reach equilibrium before
the test. A total of five samples were produced for each
combination to test the individual properties, and the
average values we re used.
To measure and calculate the water content, the gra-
vimetric method was implemented based on ISO 18369-
4:2006. For the refractive index, an ABBE Refractorme-
ter (ATAGO NAR 1T, Japan) was used based on ISO
18369-4:20 06. It maintained a temperatu re of 20˚C ± 2˚C
and measured the samples after removing the moisture
from the contact lens surfaces.
To measure wettability, the contact angle was meas-
ured by using a Phoenix-Mini from the S.E.O. For con-
tact angle measurement, the sessile drop method was
used to measure the angles of the surface of contact lens
samples after dropping pure distilled water at room tem-
perature.
Spectral transmittance was obtained by using the spec-
tral transmittance meter (TOPCON TM-2, Japan), and
Table 1. Percent compositions of samples. Unit: %.
HEMAMMANVP EGDMA
+4-VA ZnO
Ref. 93.90 0.94 4.69 0.47 - -
VA-193.02 0.93 4.65 0.47 0.93 -
VA-292.17 0.92 4.61 0.46 1.84 -
VA-391.32 0.91 4.57 0.46 2.74 -
VA-490.50 0.90 4.52 0.45 3.62 -
VA-589.69 0.90 4.48 0.45 4.48 -
Ref._Z93.68 0.94 4.68 0.47 0.00 0.23
VA_Z-192.81 0.93 4.64 0.46 0.93 0.23
VA_Z-291.95 0.92 4.60 0.46 1.84 0.23
VA_Z-391.12 0.91 4.56 0.46 2.73 0.23
VA_Z-490.29 0.90 4.51 0.45 3.61 0.23
VA_Z-589.49 0.89 4.47 0.45 4.47 0.22
+4-VA: 4-vinylaniline .

Physical Properties of Ophthalmic Copolymers Containing Vinylaniline and ZnO Nanoparticles 311
the transmittance of UV-B, UV-A and visible ray were
represented in terms of percentage.
To analyze the nano-particles contained in the poly-
mers, an atomic force microscope (XE-100, Parks Sys-
tem) and FE-SEM (JSM-7500F+EDS, Oxford) were
used.
3. Result and Discussion
3.1. Polymerization and Production
Basic combinations of contact lenses were used in the
test, and the Ref. combination produced colorless and
transparent contact lenses. Since it was hydrated in stan-
dard saline for 24 hours, it sho wed generally flexible and
soft properties. The combination with the addition of
ZnO nanoparticles tended to result in pale white-colored
transparent contact lenses. The combination to which
4-vinylaniline was added to the basic combination or the
Ref. combination generated a high performance poly-
merthat featured a transparent brown tint. Overall, the
greater the proportion of added substances, the more
visible their colors were. Since all the combinations were
soaked in standard saline for 24 hours, they were all
flexible and soft.
After analyzing the surface conditions and the combi-
nations with ZnO nanoparticles with an atomic force
microscope, it was found that the particles of about 50 -
70 nm were evenly distributed. The analysis results of
the atomic force microscope on hydrogel contact lenses
containing ZnO nanoparticles and the photos of the
manufactured contact lenses’ appearance and colors are
shown in Figures 1-3.
3.2. Water Content and Refractive Index
After measuring the water content of the produced con-
tact lenses, it was revealed that the average water content
of the Ref. that did not contain 4-vinylaniline and ZnO
nanoparticles was 38.95%. This water content value is
similar to normal hydrogel contact lenses. The average
water contents of the VA combination to which 4-viny-
laniline was added in different proportions were VA-1
(37.11%), VA-2 (35.72%), VA-3 (33.99%), VA-4
(33.18%), and VA-5 (31.10%). Overall, greater propor-
tions of 4-vinylaniline tended to result in less water con-
tent. It was deemed that the vinyl group that is suscepti-
ble to polymerization played a role in attaining the hy-
drophobic properties.
The average water content of the Ref._Z combination
made by adding the Ref. combination with ZnO nanopar-
ticles was measured as 38.45%. This water content value
is similar to normal hydrogel contact lenses, as well as
the Ref. combination. The average water contents of the
VA combination to which ZnO nanoparticles were added
were VA_Z-1 (37.06%), VA_Z-2 (34.88%), VA_Z-3
Figure 1. Photograph of tinted hydrogel lens.
(34.36%), VA_Z-4 (32.75%) and VA_Z-5 (30.62%).
Overall, greater proportions of 4-vinylaniline tended to
result in less water content. It was found that the varia-
tion in water content induced by the addition of ZnO
nanoparticles was not very significant. After measuring
the refractive index of the produced contact lenses, the
average refractive index for Ref. to which 4-vinylaniline
and ZnO nanoparticles were not added was 1.4352. The
average refractive index of the Ref. combination to
which 4-vinylaniline was added in different proportions
fell into the range of 1.4472 - 1.4780. In general, greater
proportions of 4-vinylaniline tended to result in greater
refractive index. The average water content of the Ref._Z
combination made by adding the Ref. combination with
ZnO nanoparticle fell into the range of 1.4450 - 1.4780.
Just like VA combination, greater proportions of 4-viny-
laniline resulted in greater refractive index. It was found
that the variation in refractive index by the addition of
ZnO nanoparticles was not very significant. Table 2 shows
the water content and refractive index of each sample.
3.3. Wettability
As the contact angle was measured to evaluate the wet-
tability of the produced contact lenses, it was found that
the average contact angle for the Ref. without 4-viny-
laniline and ZnO nanoparticles was 46.96˚. The average
contact angle of the Ref._Z combination made by adding
the Ref. combination with ZnO nanoparticles was meas-
ured as low as 42.02˚, indicating that the additio n of ZnO
nanoparticles influenced the contact angle. The average
contact angles of the VA combination to which 4-viny-
laniline was added in different proportions were VA-1
(54.95˚), VA-2 (58.57˚), VA-3 (64.68˚), VA-4 (71.45˚),
and VA-5 (76.67˚). In general, greater proportions of
4-vinylaniline tended to result in larger contact angles,
leading to a drop in wettability. This was apparently
caused by the hydrophobic properties of 4-vinylaniline,
which blocked the wettability on the surface.
The average contact angles of the VA_Z combination

Physical Properties of Ophthalmic Copolymers Containing Vinylaniline and ZnO Nanoparticles 312
Figure 2. Surface analysis of macromolecule by AFM images (Ref._Z).
made by adding 4-vin ylaniline to th e Ref._Z co mbination
in different proportions were VA_Z-1 (51.18˚), VA_Z-2
(54.37˚), VA_Z-3 (60.29˚), VA_Z-4 (73.60˚), and
VA_Z-5 (78.48˚). Just like VA combination, greater pro-
portions of 4-vinylaniline tended to result in larger con-
tact angles and decreased wettability. It was found that
the addition of ZnO nanoparticles reduced the overall
contact angle. Nevertheless, the combination with a high
proportion of 4-vinylaniline did not exhibit a drop in
contact angle. It can be conjectured that in a combination
with a large proportion of 4-vinylaniline, wettability was
influenced more by 4-vin ylaniline than by ZnO nanopar-
ticles. Figure 4 shows the variation in contact angle in
each sample while Figure 5 represents the measurement
results for contact angles.
Figure 3. SEM image of contact lens sample (Ref._Z).
Table 2. It presents the water content and refractive index
measuremen t results for each sample.
sample 2
*
HO

(%) Refractive index
Ref. 38.95 1.4352
VA-1 37.11 1.4472
VA-2 35.72 1.4578
VA-3 33.99 1.4662
VA-4 33.18 1.4704
VA-5 31.10 1.4780
Ref._Z 38.45 1.4332
VA_Z-1 37.06 1.4450
VA_Z-2 34.88 1.4590
VA_Z-3 34.36 1.4640
VA_Z-4 32.75 1.4702
VA_Z-5 30.62 1.4780
3.4. Spectral Transmittance
The average transmittance was 90.06% for visible rays of
the Ref. without 4-vinylaniline and ZnO nanoparticles.
The transmittance ratio was 78.4% for UV-B and 85.0%
for UV-A. In general, the transmittance in all regions was
high, but it did not block ul t r aviolet rays .
In the VA combination in which 4-vinylaniline was
added in different proportions to the Ref. combination,
the visible ray transmittances were in the range of 81.6%
- 87.2%. Although, greater proportions of 4-vinylaniline
tended to be accompanied by lower visible ray transmit-
tance, it appeared that this was due to a decrease in per-
meability in 400 - 450 nm rather than a drop of trans-
parency. The average UV-B transmittance ratio of the
VA combination was measured as 0.4% - 6.0%, indicat-
ing that it completely blocked UV-B. For the UV-A
transmittance ratio, it was measured as 12.6% - 43.4%,
which meant that it blocked some UV-A. In general, it
2
*
HO

is the water content.

Physical Properties of Ophthalmic Copolymers Containing Vinylaniline and ZnO Nanoparticles 313
Figure 4. Effect of 4-vinylaniline on contact angle.
Figure 5. Contact angle photographs of contact lens samples
(a) Ref.; (b) Ref._Z; (c) VA-5; (d) VA_Z-5.
was found that greater proportions of 4-vinylaniline re-
sulted in smaller visible ray transmittance ratios. This
proves that 4-vinylaniline has ultraviolet ray blocking
properties. Figure 6 depicts the comparison graphs for
the Ref. combination and VA-5 combination.
In the Ref._Z combinatio n in which ZnO nanoparticles
were added to the Ref. combination, the transmittance
ratio was 83.4% for visible rays. The transmittance ratio
was 40.0% for UV-B and 45.8% for UV-A. In general,
the visible ray transmittance in comparison to the Ref.
combination fell in all reg ions, especially in the ultravio-
let ray region. In case of the ZnO nanoparticles, it was
found that it has some ultraviolet block ing ability. Figure
7 represents the spectral transmittance comparison graphs
of the Ref. combination and Ref.-Z combination.
In the VA_Z combination made by adding 4-viny-
laniline to the Ref._Z combination in different propor-
tions, it was revealed that the visible ray transmittance
was in the range of 71.8% - 77.8%. Overall, greater pro-
portions of 4-vinylanilin e tended to result in smaller visi-
ble ray transmittance. The UV-B transmittance was mea-
sured as 0.2% - 2.0%, signifying complete UV blocking,
whereas that of UV-A was from 5.8% to 17.6%, which
shows a significant ability to block UV-A. The VA_Z
Figure 6. Spectral transmittances of samples (Ref. and
VA-5).
Figure 7. Spectral transmittances of samples (Ref. and
Ref._Z).
combination, compared to the VA combination to which
ZnO nanoparticles were not added, had a sizably low
spectral transmittance for UV-A, which seemed to be
attributable to the influence of the ZnO nanoparticle.
Furthermore, the visible ray transmittance was also low,
which could be due to the overall decrease in transmit-
tance, rather than a specific region. Figure 8 presents the
spectral transmittance comparison graphs for the VA-3
combination and VA_Z-3 combination. The spectral
transmittance results in all combinations are shown in
Table 3.
4. Conclusions
In th i s r es e arch , the hydrogel contact lens es mat er i al s t h at
contain ZnO nanoparticles with luminescence property in
the ultraviolet region were prepared and their physical
and optical properties were investigated. 4-Vinlyaniline
which is used as an ingredient of dyes and ZnO nanopar-
ticles was added in different proportions to analyze the
variations in their physical and optical properties.
The color of the produced high performance polymers
generally ranged from pale gray to yellowish brown due
to the ZnO nanoparticles and 4-vinlyaniline and their
color concentrations differed depending on the added
proportions. Larger proportion s of 4-vinlyaniline showed
a decrease in water content but an increase in refractive

Physical Properties of Ophthalmic Copolymers Containing Vinylaniline and ZnO Nanoparticles 314
Figure 8. Spectral transmittances of samples (VA-3 and
VA_Z-3).
Table 3. Spectral transmittances of samples.
sample UV-B UV-A Vis.
Ref. 78.4 85.0 90.6
VA-1 6.0 43.4 87.2
VA-2 2.0 28.6 85.4
VA-3 1.0 22.8 85.2
VA-4 1.0 21.4 83.6
VA-5 0.4 12.6 81.6
Ref._Z 40.0 45.8 83.4
VA_Z-1 2.0 17.6 77.8
VA_Z-2 0.6 11.0 74.0
VA_Z-3 0.4 11.0 76.8
VA_Z-4 0.2 6.8 73.8
VA_Z-5 0.2 5.8 71.8
index. And it was uncovered that the addition of ZnO
nanoparticles played a negligible role. The wettability of
contact lens tended to diminish with the increase in the
proportion of 4-vinlyaniline. The addition of ZnO nano-
particle was also shown to exert some influence over
contact angle.
In terms of spectral transmittance, the addition of ZnO
nanoparticles led to the decreasing in transmittance ratio
in the ultraviolet region. If 4-vinlyaniline was added, it
also reduced the transmittance ratio in the ultraviolet
region.
It is expected that the results would contribute to a
wider application of contact lenses containing ZnO nano-
particles which are to be used as ultraviolet ray blocking
contact lenses, and aniline-group materials can be employ-
ed to show pale colors in hydrophilic lenses and utilized
as an ultraviolet ray blocking contact lens material.
REFERENCES
[1] T. H. Kim, K. H. Ye and A. Y. Sung, “UV-Blocking Ef-
fect of Ophthalmic Material Containing Benzophenone,”
Journal of the Korean Chemical Society, Vol. 53, No. 3,
2009, pp. 391-398.
http://dx.doi.org/10.5012/jkcs.2009.53.3.391
[2] K. Diduch, R. Wubbenhorst and S. Kucharski, “Photo-
current Generation of Bi-Functional Carbazole Contain-
ing Polymers,” Synthetic Metals, Vol. 139, No. 2, 2003,
pp. 515-520.
http://dx.doi.org/10.1016/S0379-6779(03)00352-7
[3] V. A. Soloukhin, W. Postumus, J. C. M. Brokken-Zijp
and J. Loos, “Mechanical Properties of Silica-(Meth)-
Acrylate Hybrid Coatings on Polycarbonate Substrate,”
Polymer, Vol. 43, No. 23, 2002, pp. 6169-6181.
http://dx.doi.org/10.1016/S0032-3861(02)00542-6
[4] T. H. Kim and A. Y. Sung, “Copolymerization and Con-
tact Lens Application of HEMA-Substituted Polyphos-
phazene,” Journal of the Korean Chemical Society, Vol.
53, No. 3, 2009, pp. 340-344.
http://dx.doi.org/10.5012/jkcs.2009.53.3.340
[5] T. H. Kim, K. H. Ye, Y. S. Kwon and A. Y. Sung, “Study
on the Silicone Contact Lens Using AA and BMA,” Jour-
nal of the Korean Ophthalmic Optics Society, Vol. 11, No.
3, 2006. pp. 259-265.
[6] K. Vimala, M. M. Yallapu, K. Varaprasad, N. Narayana
Reddy, S. Ravindra, N. S. Naidu and K. MohanaRaju,
“Fabrication of Curcumin Encapsulated Chitosan-PVA
Silver Nanocomposite Films for Improved Antimicrobial
Activity” Journal of Biomaterials and Nanobiotechnol-
ogy, Vol. 2, No. 1, 2011, pp. 55-64.
http://dx.doi.org/10.4236/jbnb.2011.21008
[7] K. H. Ye, S. H. Choi and A. Y. Sung, “Study on the An-
tibiosis and Physical Properties of Copolymer Containing
Silver,” Journal of the Korean Chemical Society, Vol. 53,
No. 3, 2009, pp. 562-546.
[8] K. H. Ye and A. Y. Sung, “Synthesis of Poly mer Materi-
als Containing Platinum Nanoparticles and Their Appli-
cation for Contact Lenses,” Journal of the Korean Che-
mical Society, Vol. 54, No. 1, 2010, pp. 99-104.
http://dx.doi.org/10.5012/jkcs.2010.54.01.099
[9] K. H. Ye and A. Y. Sung, “Study on the Synthesis and
Physical Properties of Ophthalmic Polymer Containing
Gold Nanoparticles,” Journal of the Korean Chemical
Society, Vol. 54, No. 2, 2010, pp. 222-227.
http://dx.doi.org/10.5012/jkcs.2010.54.02.222
[10] R. W. Young, “Solar Radiation and Age-Related Macular
Degeneration,” Survey of Ophthalmology, Vol. 32, No. 4,
1998, pp. 252-269.
http://dx.doi.org/10.1016/0039-6257(88)90174-9
[11] W. S. Duke-Elder and P. M. Duke-Elder, “A Histological
Study on the Action of Short-Waved Light upon the Eye,
with a Note on ‘Inclusion Bodies’,” British Journal of
Ophthalmology, Vol. 13, No. 1, 1929, pp. 1-37.
http://dx.doi.org/10.1136/bjo.13.1.1
[12] S. Zigman, T. Yulo and J. Schultz, “Cataract Induction in
Mice Exposed to near UV Light,” Ophthalmic Research,
Vol. 6, No. 2-4, 1974, pp. 259-270.
http://dx.doi.org/10.1159/000264710
[13] M. Kennedy, K. H. Kim, B. Harten, et al., “Ultraviolet
Irradiation Induces the Production of Multiple Cytokines
by Human Corneal Cells,” Investigative Ophthalmology

Physical Properties of Ophthalmic Copolymers Containing Vinylaniline and ZnO Nanoparticles 315
& Visual Science, Vol. 38, No. 12, 1997, pp. 2483-2491.
[14] A. Podskochy, L. Gan and P. Fagerholm, “Apoptosis in
UV-Exposed Rabbit Corneas,” Cornea, Vol. 19, No. 1,
2000, pp. 99-103.
http://dx.doi.org/10.1097/00003226-200001000-00019
[15] C. X. Cai, D. E. Birk and T. F. Linsenmayer, “Nuclear
Ferritin Protects DNA from UV Damage in Corneal
Epithelial Cells,” Molecular Biology of the Cell, Vol. 9,
No. 5, 1998, pp. 1037-1051.
http://dx.doi.org/10.1091/mbc.9.5.1037
[16] T. H. Kim and A. Y. Sung, “Study on the High-Perfor-
mance Lens Material Containing 4-Vinylpyridine,” Jour-
nal of the Korean Chemical Society, Vol. 54, No. 4, 2010,
pp. 487-490.
[17] T. H. Kim and A. Y. Sung, “Study on the Opthalmic Lens
Materials with High Refractive Index Containing Vi-
nylanisole,” Journal of the Korean Chemical Society, Vol.
54, No. 6, 2010, pp. 755-760.
http://dx.doi.org/10.5012/jkcs.2010.54.6.755
[18] T. H. Kim and A. Y. Sung, “Study on the Ophthalmic
Optical Application of Poly(HEMA-co-FMA) Containing
2,3-Naphthalocyanine Bis(trihexylsilyloxide),” Journal of
the Korean Chemical Society, Vol. 55, No. 4, 2011, pp.
723-728. http://dx.doi.org/10.5012/jkcs.2011.55.4.723