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Evaluation of Pollen Adhesion to Verofilcon-A Soft Contact Lenses

Bentham Science
The Open Ophthalmology Journal
Authors:

Abstract and Figures

Purpose A new 1-day disposable soft contact lens (SCL), verofilcon-A, constructed of silicone hydrogel material, has recently become available in Japan. This SCL has a very smooth surface produced by using the SMARTSURFACE ® Technology, and it was expected that pollen particles and protein components would not adhere easily to its surface. We examined the degree of pollen adhesion to the surface of the verofilcon-A material SCL and compared the results with those of other 1-day disposable SCLs (1DSCL). Methods To determine the number of pollen grains attached to the surface of different types of SCLs, 0.01 mg/ml of cedar pollen solution was dropped onto the surface of 13 types of 1DSCL. After 24 h, each 1DSCL was rinsed in a shaker and washed five times with saline (n = 10 for each 1DSCL type). The number of pollen particles adhered to the 1DSCL and the percentage of surface area occupied by pollen was determined. Results The number of pollen particles on the 1DSCLs ranged from 0 to 185 in the 200 × 200 µm area. The number of particles was lowest in the delefilcon-A and verofilcon-A SCLs with 0 particles, and the number was higher in the other 11 1DSCLs. The number of pollen particles was negatively correlated with the water content (r = −0.48), oxygen permeability (Dk; r = −0.43), oxygen transmissibility (r = −0.42), and center thickness (r = −0.33) of the 1DSCLs. The pollen adhesion area ranged from 0.0% to 3.1% and was lowest in the delefilcon-A and verofilcon-A 1DSCLs. There were significant differences in the pollen adhesion area between colored 1DSCLs (2.73 ± 1.97%) and clear 1DSCLs (1.03 ± 1.01%, P<0.001) and between hydroxyethyl methacrylate-based 1DSCLs (1.84 ± 1.45%) and silicone hydrogel-based 1DSCLs (0.05 ± 0.16%, P<0.001). Conclusion These findings indicate that the verofilcon-A 1DSCL processed with SMARTSURFACE™ Technology is an excellent option for SCL users with allergic conjunctivitis during the high pollen season.
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305
DOI: 10.2174/1874364102115010305, 2021, 15, 305-313
The Open Ophthalmology Journal
Content list available at: https://openophthalmologyjournal.com
RESEARCH ARTICLE
Evaluation of Pollen Adhesion to Verofilcon-A Soft Contact Lenses
Tatsuya Mimura1,*, Hiroshi Fujishima2, Eichi Uchio3, Kazumi Fukagawa4,5, Yuji Inoue1, Makoto Kawashima1, Kazuma
Kitsu1 and Atsushi Mizota1
1Department of Ophthalmology, Teikyo University School of Medicine, Itabashi-ku, Tokyo, Japan.
2Department of Ophthalmology, Tsurumi University School of Dental Medicine, Tsurumi-ku, Yokohama, Kanagawa, Japan.
3Department of Ophthalmology, Fukuoka University School of Medicine, Jounan-ku, Fukuoka, Japan.
4Ryogoku Eye Clinic, Sumida-ku, Tokyo, Japan
5Department of Ophthalmology, Keio University School of Medicine, Shinjuku-ku, Tokyo, Japan
Abstract:
Purpose:
A new 1-day disposable soft contact lens (SCL), verofilcon-A, constructed of silicone hydrogel material, has recently become available in Japan.
This SCL has a very smooth surface produced by using the SMARTSURFACE ® Technology, and it was expected that pollen particles and
protein components would not adhere easily to its surface. We examined the degree of pollen adhesion to the surface of the verofilcon-A material
SCL and compared the results with those of other 1-day disposable SCLs (1DSCL).
Methods:
To determine the number of pollen grains attached to the surface of different types of SCLs, 0.01 mg/ml of cedar pollen solution was dropped onto
the surface of 13 types of 1DSCL. After 24 h, each 1DSCL was rinsed in a shaker and washed five times with saline (n = 10 for each 1DSCL type).
The number of pollen particles adhered to the 1DSCL and the percentage of surface area occupied by pollen was determined.
Results:
The number of pollen particles on the 1DSCLs ranged from 0 to 185 in the 200 × 200 µm area. The number of particles was lowest in the
delefilcon-A and verofilcon-A SCLs with 0 particles, and the number was higher in the other 11 1DSCLs. The number of pollen particles was
negatively correlated with the water content (r = −0.48), oxygen permeability (Dk; r = −0.43), oxygen transmissibility (r = −0.42), and center
thickness (r = −0.33) of the 1DSCLs. The pollen adhesion area ranged from 0.0% to 3.1% and was lowest in the delefilcon-A and verofilcon-A
1DSCLs. There were significant differences in the pollen adhesion area between colored 1DSCLs (2.73 ± 1.97%) and clear 1DSCLs (1.03 ±
1.01%, P<0.001) and between hydroxyethyl methacrylate-based 1DSCLs (1.84 ± 1.45%) and silicone hydrogel-based 1DSCLs (0.05 ± 0.16%,
P<0.001).
Conclusion:
These findings indicate that the verofilcon-A 1DSCL processed with SMARTSURFACE™ Technology is an excellent option for SCL users with
allergic conjunctivitis during the high pollen season.
Keywords: Daily soft contact lens, Pollen, Silicone hydrogel, Verofilcon-A, Allergens, Conjunctivitis.
Article History Received: July 07, 2021 Revised: September 21, 2021 Accepted: November 15, 2021
1. INTRODUCTION
Seasonal allergic conjunctivitis is usually caused by
airborne allergens, such as the pollen of trees, grasses, and
weeds, and worsens during the high pollen season. The typical
* Address correspondence to this author at the Department of Ophthalmology,
Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo,
173-8605 Japan; Tel: +81-3-3964-1211; Fax: +81-3-3964-1402;
E-mail: mimurat-tky@umin.ac.jp
signs of seasonal allergic conjunctivitis are mild to moderate
itching, redness, and swelling of the conjunctiva [1, 2]. Soft
contact lenses (SCLs) also cause giant papillary conjunctivitis
(GPC), a subtype of allergic conjunctivitis. However, contact
lens-induced GPC is not real allergic conjunctivitis, but is
considered a chronic ocular inflammation [1, 3]. During wear,
the SCLs accumulate tear film deposits3 including proteins [4,
5], lipids [6], and mucins [7]. The Food and Drug
306 The Open Ophthalmology Journal, 2021, Volume 15 Mimura et al.
Administration Groups II and IV SCLs are high water content
SCLs that accumulate more tear film components than Groups
I and III low water content SCLs [5, 6]. The SCLs can easily
trap various aeroallergens including tree and grass pollen, dust,
smog, and cosmetic makeup. These allergens worsen the
symptoms of allergic conjunctivitis and may cause conjunctival
inflammation [8 - 10].
An earlier study suggested that the rate of adhesion Cryj 1,
a major Japanese cedar pollen allergen, to SCLs was higher in
the monthly replacement SCLs than the daily disposable SCLs
or the 2-week frequent replacement SCLs [11]. Another study
demonstrated that the pollen adhesion to daily disposable SCLs
was higher on the colored SCLs than on the clear SCLs [12].
Additionally, pollen adhesion was lower in the silicone
hydrogel SCL than in hydroxyethyl methacrylate (HEMA) CLs
[12]. These results suggest that the daily disposable silicone
hydrogel type of SCL may be better for patients with AC,
especially during the pollen season.
Recently, a new 1-day disposable SCL (1DSCL) made of
silicone hydrogel called verofilcon-A (PRECISION1™, Alcon
Japan Ltd. Tokyo, Japan) was introduced to Japan. Verofilcon-
A is made from a new high oxygen permeability (Dk; 90 ×
10−11 barriers) material with a 2–3-µm-thick surface with more
than 80% water content and is a Class 1 ultraviolet blocker (≥
90% of UVA, ≥ 99% of UVB) [13]. The verofilcon-A SCL has
a smooth surface with the smoothing produced by
SMARTSURFACE® Technology, and it is expected that
pollen and protein components will not adhere to this type of
surface as easily. However, whether there is less pollen
adherence to verofilcon-A SCLs than other types of 1DSCLs
has not been determined.
We examined the degree of pollen adhesion to the surface
of verofilcon-A SCLs and compared the degree of pollen
adhesion to verofilcon-A daily disposable SCLs to that of other
major 1DSCLs available in Japan.
2. MATERIALS AND METHODS
2.1. Research Design
This study performed a nonclinical and comparative
analysis. This study was reviewed and approved by the Ethics
Committee of Teikyo University.
Thirteen different types of −4.0 diopter 1DSCL were tested
(n = 10 each) (Table 1). A total of 130 1DSCLs were used in
this study. Japanese cedar pollen (Cryptomeria japonica) was
purchased from the Yamizo Pollen Study Group (Daigo-cho,
Ibaraki Prefecture, Japan). According to the manufacturer’s
instructions, pollen was collected from naturally dried male
cedar flowers and purified using a filter.
2.2. Adhesion of Pollen to SCLs
0.2 ml phosphate-buffered saline (PBS) containing 0.02
mg cedar pollen was dropped onto the surface of 1DSCLs.
After that, SCLs were maintained at room temperature for 24 h
[14]. The SCL was then placed in a dish containing 10.0 ml of
PBS and shaken five times for 1 min to remove the pollen from
the surface of the SCLs. The SCL was rinsed three times in
PBS. The central part of the SCL was photographed using a
microscope. The number of pollen particles adhering to a 200
µm × 200 µm area in the central part of the SCL and the
portion of the adhering area were calculated using ImageJ
analysis software (version 1.52a).
2.3. Statistical Analyses
Two-tailed unpaired Student’s t-tests were used to
determine the significance of the differences in the mean
number of pollens among the 13 groups of SCLs. The mean
values among three or more groups were compared by one-way
analysis of variance (ANOVA) using the Tukey-Kramer
method and the Kruskal-Wallis test. Correlation analysis was
performed using two-tailed Pearson correlation coefficients.
Factors affecting the adhesion of pollen to SCLs were
investigated using multivariate logistic regression analyses.
Data are expressed as mean ± standard deviation or percentage.
If the p-value is 0.05 or lower, the result is considered
significant.
3. RESULTS
3.1. Numbers of Pollen Particles Adherent to SCLs
Fig. (1) shows the pollen particles attached to the surface
of the SCLs/200 μm × 200 μm area. The number of pollen
particles adhering to the SCL was 98 ± 51 for CL1, 77 ± 36 for
CL2, 57 ± 46 for CL3, 33 ± 16 for CL4, 25 ± 8 for CL5, 21 ± 8
for CL6, 14 ± 9 for CL7, 9 ± 5 for CL8, 6 ± 5 for CL9, 4 ± 4
for CL10, 3 ± 2 for CL11, 0 ± 0 for CL12, and 0 ± 0 for CL13
(Fig. 2). There were significant differences among the 13
groups (P<0.001).
Table 1. Characteristics of the contact lenses.
SCL
No.
Water
Content (%)
Oxygen
Permeability
(Dk)
Oxygen
Transmissibility
(Dk/L)
Diameter
(mm)
Base
Curve
(mm)
CT
(mm)
Colored
SCL
Surface
(Ionic/
Non-ionic)
FDA
group
USAN
Nomenclature
Principal
Components
1 38.6 8.5 12.1 14.2 8.7 0.08 Yes Non-ionic I Polymacon 2-HEMA, EGDMA
2 38 12 24 14.5 8.7 0.05 Yes Non-ionic I Polymacon HEMA, EGDMA
3 42.5 11 13.75 14 8.6 0.08 Yes Non-ionic I Polymacon HEMA、NVP、MMA
4 38.5 10 14.3 14 8.7 0.07 No Non-ionic I Polymacon HEMA, EGDMA
5 38.5 10 20 14 8.7 0.05 No Non-ionic I Polymacon HEMA, EGDMA
6 38 8.5 12.1 14 8.7 0.07 No Non-ionic I Polymacon HEMA, EGDMA
7 58 25.68 36.7 14.2 8.6 0.07 No Non-ionic II Omafilcon A 2-HEMA
Pollen Adhesion to Verofilcon-A The Open Ophthalmology Journal, 2021, Volume 15 307
SCL
No.
Water
Content (%)
Oxygen
Permeability
(Dk)
Oxygen
Transmissibility
(Dk/L)
Diameter
(mm)
Base
Curve
(mm)
CT
(mm)
Colored
SCL
Surface
(Ionic/
Non-ionic)
FDA
group
USAN
Nomenclature
Principal
Components
8 59 22 24.2 14.2 8.6 0.09 No Non-ionic II Hilafilcon-B HEMA, NVP
9 58 28 33.3 14.2 8.75 0.084 No Ionic IV Etafilcon-A HEMA, MA
10 55 19.7 26.3 14.2 8.6 0.075 No Ionic IV Ocufilcon-D HEMA, MA
11 38 103 121 14.3 8.75 0.085 No Non-ionic V-I Senofilcon-A DMA, HEMA, PVP
12 Core33
/Surface80
140 156 14.1 8.7 0.09 No Non-ionic V-IV Delefilcon-A CE-PDMS,
DMA, TRIS
13 Core51,
/Surface80
90 100 14.2 8.5 0.09 No Non-ionic V-IV Verofilcon A mPDMS, GPDMS,
NVP
EWC=Equilibrium water content; CT=Center thickness of contact lens; FDA=Food and Drug Administration; USAN=United States adopted names; HEMA=2-
Hydroxyethyl methacrylate; EGDMA=ethylene glycol dimethacrylate; PVA=polyvinyl alcohol; NVP=N-vinyl-pyrrolidone; MA=methacrylic acid; DMA=N,N'-dimethyl
acrylamide; PVP=polyvinylpyrrolidone; CE-PDMS=chain-extended polydimethylsiloxane; TRIS=Tris(trimethylsiloxy)silyl methacrylamide; mPDMS=mono-methacrylate
poly dimethylsiloxane; GPDMS=Glycerol-functionalized polydimethylsiloxane; NVP=N-vinyl pyrrolidone.
Fig. (1). Pollen particles remaining on the surface of each SCL after rinsing with physiological saline. Bars = 100 µm.
Fig. (2). Number of pollen particles adhered to SCL in an area of 200 µm × 200 µm in the central part of SCL after rinsing with physiological saline.
FDA Group
Components
Lens Color
I
HEMA
Color
I
HEMA
Clear
II
HEMA
Clear
IV
HEMA
Clear
V
Silicon Hydrogel
Clear
SCL No.
CL1 CL4 CL7 CL9 CL11
SCL No.
CL2 CL5 CL8 CL10 CL12
SL No.
CL3 CL6 CL13
CL No. 1 2 3 4 5 6 7 8 9 10 11 12 13
FDA group I I I I I I II II IV IV V V V
308 The Open Ophthalmology Journal, 2021, Volume 15 Mimura et al.
Fig. (3). Percentage of a 200 x 200 µm surface area that pollen has adhered to for each SCL (%).
Table 2. Relationship between the numbers of pollen particles adhered to SCLs and SCL parameters, and the results of
multivariate analyses.
- Correlation Coefficients Multivariate Analysis
Variables R (95% CI) P Value OR P Value
Water Content (%) -0.48 (-0.60 – -0.33) <0.001 0.1 0.007
Oxygen Permeability (Dk) -0.43 (-0.56 – -0.27) <0.001 00.03
Oxygen Transmissibility (Dk/L) -0.42 (-0.55 – -0.26) <0.001 329.8 0.042
Diameter (mm) 0.14 (-0.03 – 0.31) 0.109 00.704
Base Curve (mm) 0.16 (-0.02 – 0.32) 0.075 >100 0.002
Center Thickness -0.33 (-0.48 – -0.17) <0.001 >100 0.023
SCL color (clear=0/color=1) - - - >100.0 <0.001
Surface charge (non-ionic=0/ionic=1) - - - 0<0.001
FDA classification - - - >100.0 0.002
3.2. Degree of Pollen Particles Adherent to SCL
The percentage of the 200 × 200 um surface area of a SCL
that was covered by pollen was 3.15 ± 2.55% in CL1, 2.65 ±
1.66% in CL2, 2.40 ± 1.43% in CL3, 2.38 ± 1.16% in CL4,
2.11 ± 0.66% in CL5, 1.76 ± 0.54% in CL6, 1.51 ± 0.90% in
CL7, 1.21 ± 0.23% in CL8, 0.72 ± 0.29% in CL9, 0.48 ±
0.31% in CL10, and 0.16 ± 0.25% in CL11. The percentage of
pollen adhered area was 3.16 ± 2.54% in CL1, 1.15 ± 1.11% in
CL2, 3.07 ± 2.02% in CL3, 1.44 ± 1.24% in CL4, 3.15 ±
1.43% in CL5, 2.77 ± 2.16% in CL6, 0.61 ± 0.39% in CL7,
0.04 ± 0.07% in CL8, 0.51 ± 0.40% in CL9, 1.24 ± 0.77% in
CL10, 0.66 ± 0.61% in CL11, 0.00 ± 0.00% in CL12, and 0.00
± 0.00% in CL13 (Fig. 3). There was a significant difference
among the 13 groups (one-way ANOVA, P<0.001).
3.3. Factors Affecting Adhesion of Pollen Particles to SCLs
There were significant negative correlations between the
number of pollen particles adhered to the SCLs and some
parameters of SCL, such as the water content (r = −0.48),
oxygen permeability (r = −0.43), oxygen transmissibility (r =
−0.42), and center thickness (r = −0.33) (Table 2).
Correlations between the number of pollen particles
adhered to SCLs and parameters of SCLs were calculated with
the two-tailed Pearson’s product moment formula. Independent
determinants of the number of adhered pollen particles were
investigated by multiple logistic regression analysis. R =
Pearson’s correlation coefficient; CI = confidence interval; OR
= odds ratio.
Fig. (4) shows the correlations between the portion of the
pollen adhesion area and each characteristic of the SCLs. The
area of pollen adhered to SCLs was significantly higher for
colored SCLs than for clear SCLs (2.73 ± 1.97% vs. 1.03 ±
1.01%, P<0.001). The area of pollen adhered to SCLs was
negatively correlated with water content (r = −0.51), oxygen
permeability (r = −0.54), oxygen transmissibility (r = −0.54),
and center thickness (r = −0.42).
CL No. 1 2 3 4 5 6 7 8 9 10 11 12
13
FDA group I I I I I I II II IV IV V V
V
Pollen Adhesion to Verofilcon-A The Open Ophthalmology Journal, 2021, Volume 15 309
y = -0.0508x + 4.0081
r = -0.51
0
1
2
3
4
5
010 20 30 40 50 60 70 80 90 100
Adhesion Area
of Pollen Particles (%)
Water content (%)
A
y = -0.0191x + 2.1436
r = -0.54
0
1
2
3
4
5
020 40 60 80 100 120 140 160
Adhesion Area
of Pollen Particles (%)
Oxygen Permeability (Dk)
B
C
310 The Open Ophthalmology Journal, 2021, Volume 15 Mimura et al.
y = -0.9146x + 14.373
r = -0.08
0
1
2
3
4
5
13.6 13.8 14 14.2 14.4 14.6
Adhesion Area
of Pollen Particles (%)
Diameter of SCL (mm)
D
y = 2.056x - 16.38
r = 0.14
0
1
2
3
4
5
8.4 8.6 8.8
Adhesion Area
of Pollen Particles (%)
Base Curve of SCL (mm)
E
y = -47.726x + 5.0382
r = -0.42
0
1
2
3
4
5
0 0.02 0.04 0.06 0.08 0.1 0.12
Adhesion Area
of Pollen Particles (%)
Center thickness of SCL (mm)
F
Pollen Adhesion to Verofilcon-A The Open Ophthalmology Journal, 2021, Volume 15 311
Fig. (4). Relationship between the portion of pollen adhesion area and various parameters of SCLs. (A) Water content (%). (B) Oxygen permeability
(Dk). (C) Oxygen transmissibility (Dk/L). (D) Diameter (mm). (E) Base curve (mm). (F) Center thickness (mm). (G) Comparison between colored
and clear SCLs by the unpaired t-test. (H) Comparison of chargeability on SCL surface among non-ionic (HEMA), non-ionic (silicon hydrogels), and
ionic SCLs by one-way analysis of variance. (I) FDA classification group.
0
1
2
3
4
5
Percentage of Particle
Attachment Area (%)
Color SCL Clear SCL
P<0.001
G
0
1
2
3
4
5
Percentage of Particle
Attachment Area (%)
Non-ionic Non-ionic Ionic
(HEMA)
P<0.001
(Silicone
Hydrogel)
H
0
1
2
3
4
5
Percentage of Particle
Attachment Area (%)
I II III IV
FDA classification group
P<0.001
Silicone
Hydrogel
I
312 The Open Ophthalmology Journal, 2021, Volume 15 Mimura et al.
The pollen adhesion area was smaller in the silicone
hydrogel SCLs (SCL11–13; 0.05 ± 0.16%) than in the
hydroxyethyl methacrylate HEMA SCLs (CL1 to CL10, 1.84 ±
1.45%, P<0.001). The portion of pollen adhesion area was
lowest in both silicone hydrogel SCLs made with delefilcon-A
(0.00 ± 0.00%) and verofilcon-A (0.00 ± 0.00%) (Fig. 4).
4. DISCUSSION
Our results showed that the number of pollen particles
adhered to 13 different 1DSCLs varied from 0 to 185 particles
per 200 × 200 µm area. Pollen adhesion was higher in the
colored SCLs and lower in the silicone hydrogel SCLs. These
results indicate that the degree of pollen adherence to the
surface of the new verofilcon-A clear silicon hydrogel SCLs
was very low.
In general, SCLs made of silicone hydrogel have the
advantages of high oxygen permeability and resistance to
drying [15]. However, some SCLs made of solid materials are
still not comfortable to wear. To overcome the weaknesses of
these silicone hydrogel materials, verofilcon-A SCL has
succeeded in improving the wearing comfort with its unique
technology called “SMARTSURFACE™ Technology” [16].
The surface of the verofilcon-A SCL has a high water content
of 80% or more, which is accomplished by covering the
surface of the SCL with a highly water-retaining hydrophilic
polymer. SMARTSURFACE® is based on a manufacturing
process in which the CLs are immersed in a liquid filled with a
water-soluble polymer containing a hydrogel polymer and
polyacrylic acid (PAA). PAA is a very hydrophilic polymer
capable of absorbing large amounts of water, producing a
“hydrogel.” PAA is a major contributor to the high water
content of verofilcon-A SCL, which has a 51% water core
wrapped in a gel-like outer layer that transitions to 80% at the
surface [16]. In the processing stage of SMARTSURFACE™
Technology, this hydrophilic polymer solution expands the lens
material to create small and narrow pores on the lens surface
that are 2–3 microns in diameter [16]. The water-loving PAA
polymer penetrates the open pores and is locked into place,
creating a micro-thin layer of moisture. In addition, the heating
process crosslinks the PAA polymer with a wetting agent
consisting of a copolymer of polyamide amine and
polyacrylamide-acrylic acid. This thin layer of PAA on the lens
surface provides long-lasting moisture, support for stabilizing
the tear film, and smoothness of the lens surface. These
properties lead to long-lasting comfort and clear vision,
according to the company’s literature [16]. The moderately
hard structure in the center of the SCL makes it easier for SCL
wearers to handle it when inserting and wearing these SCLs. In
fact, 82% of new SCL wearers have reported that verofilcon-A
SCLs are easy to place on the cornea and 72% agreed that they
are easy to remove at the end of the day [17]. Furthermore, in a
questionnaire survey of SCL wearers, verofilcon-A SCLs were
reported to provide high quality of vision, comfort of wearing,
and easy handling of wearing [18, 19]. SMARTSURFACE™
Technology is expected to not only improve the comfort of
wearing SCLs but also reduce the adhesion of proteins and air
dust on the SCL surface. In fact, our results showed that
verofilcon-A SCLs had lower pollen adhesion than the other
SCLs. As parameters for SCLs other than verofilcon-A, the
water content, oxygen permeability, and oxygen
transmissibility had a negative and significant correlation with
the number of pollen particles adhered to the SCLs (Table 2).
In addition, the colored SCLs and non-ionic HEMA SCLs had
a high pollen adhesion number (Table 2). Generally, SCLs
made with HEMA material have more protein adhesion than
silicone hydrogel SCLs [20]. Because the silicone materials are
hydrophobic and lipophilic, the silicone SCLs repel tears and
are prone to the adherence of lipid particles. Therefore, to
improve the wettability of the SCL surface, silicone hydrogel
SCLs are coated with a hydrogel-rich material [20]. SCLs are
coated with a variety of substances after being soaked in a
dispersion of positively charged particles (DOWEX™) [20].
Therefore, positively charged pollen particles do not easily
adhere to the SCLs treated with a positively charged material.
We used SCLs made of different materials: polymacon,
omafilcon A, hilafilcon-B, etafilcon-A, ocufilcon-D,
senofilcon-A, delefilcon-A, and verofilcon-A. All of these are
very popular SCLs available in Japan. Of the 13 types of
lenses, 11 lenses, excluding delefilcon-A and verofilcon-A,
were different types of SCLs from the SCLs examined in
earlier studies [12]. Nevertheless, the results regarding pollen
adhesion to the SCL surface were similar to those of earlier
studies using different lenses [12]. These results support the
idea that SCL materials are involved in the degree of pollen
adhesion to SCLs. That is, SCLs of non-ionic HEMA material,
low water content, low oxygen permeability, and low oxygen
transmissibility are those that pollen tends to adhere to.
The pollen adhesion area was not related to the base curve
of the SCLs (Fig. 4). We examined only the center part of the
SCL; therefore, the curvature of the entire surface of the SCLs
probably did not affect pollen adhesion. In addition, there were
only 4 types of lens curvatures, 8.5 mm, 8.6 mm, 8.7 mm, and
8.75 mm, which may have contributed to the absence of
statistical significance. The center thickness of the SCLs was
negatively correlated with the degree and area of pollen
adhesion (Fig. 4). The center thickness of SCLs ranged from
0.05 to 0.09 mm (Table 1). The thickness of silicone hydrogel
SCLs with less pollen adhesion was very thick (0.085–0.09
mm, CL11, CL12, and CL13; (Table 1). Therefore, the
relationship between SCL center thickness and pollen adhesion
may be influenced by the properties of the SCL material,
especially the silicone hydrogel material.
This study has several limitations. First, the amount of
pollen used was much higher (approximately 2,500 pollen/mm2
dropped on the surface of SCLs) than the general amount of
pollen floating in the air (approximately 100 particles/cm2/day
in Tokyo from March to April 2021). Second, the pollen
adhesion experiments were only verified using 1DSCLs. The
properties of 2-week and monthly replacement SCLs or
conventional SCLs deteriorate over a long period of use and
easily adsorb proteins. Therefore, rather than the 1DSCLs, a
study of pollen adhesion to the 2-week frequent replacement
SCLs or conventional SCLs may be useful for CL users.
CONCLUSION
In conclusion, the adherence of pollen and protein to SCL
was lowest for verofilcon-A processed with SMART
Pollen Adhesion to Verofilcon-A The Open Ophthalmology Journal, 2021, Volume 15 313
SURFACE™ Technology. Thus, verofilcon-A, like the
delefilcon-A, maybe the best SCL for users with hay fever or
allergic conjunctivitis.
ETHICS APPROVAL AND CONSENT TO PARTI-
CIPATE
This study was reviewed and approved by the Ethics
Committee of Teikyo University, Tokyo, Japan (#Teirin
20-166).
HUMAN AND ANIMAL RIGHTS
No animals were used in this research. All human research
procedures were followed in accordance with the ethical
standards of the committee responsible for human
experimentation (institutional and national), and with the
Helsinki Declaration of 1975, as revised in 2013.
CONSENT FOR PUBLICATION
Not applicable.
AVAILABILITY OF DATA AND MATERIALS
The data that support the findings of this study are
available from the corresponding author [T.M], upon
reasonable request.
FUNDING
This work was supported in part by a Grant-in-Aid for
Scientific Research from the Ministry of Education, Culture,
Sports, Science and Technology of Japan (grant number
20H04347) and an unrestricted investigator-initiated grant from
Alcon Japan Ltd. to Tatsuya Mimura, MD.
CONFLICT OF INTEREST
Dr. Tatsuya Mimura is the Editor-in-Chief of The Open
Ophthalmology Journal.
ACKNOWLEDGEMENTS
We would like to thank Editage (www.editage.com) for
English language editing.
REFERENCES
La Rosa M, Lionetti E, Reibaldi M, et al. Allergic conjunctivitis: a[1]
comprehensive review of the literature. Ital J Pediatr 2013; 39: 18.
[http://dx.doi.org/10.1186/1824-7288-39-18] [PMID: 23497516]
Wong AH, Barg SS, Leung AK. Seasonal and perennial allergic[2]
conjunctivitis. Recent Pat Inflamm Allergy Drug Discov 2009; 3(2):
118-27.
[http://dx.doi.org/10.2174/187221309788489733] [PMID: 19519588]
Leonardi A, Motterle L, Bortolotti M. Allergy and the eye. Clin Exp[3]
Immunol 2008; 153(Suppl 1): 17-21.
[http://dx.doi.org/10.1111/j.1365-2249.2008.03716.x]
Lin ST, Mandell RB, Leahy CD, Newell JO. Protein accumulation on[4]
disposable extended wear lenses. CLAO J 1991; 17(1): 44-50.
[PMID: 2007285]
Luensmann D, Jones L. Albumin adsorption to contact lens materials:[5]
a review. Cont Lens Anterior Eye 2008; 31(4): 179-87.
[http://dx.doi.org/10.1016/j.clae.2008.05.004] [PMID: 18603467]
Jones L, Evans K, Sariri R, Franklin V, Tighe B. Lipid and protein[6]
deposition of N-vinyl pyrrolidone-containing group II and group IV
frequent replacement contact lenses. CLAO J 1997; 23(2): 122-6.
[PMID: 9108978]
Berry M, Pult H, Purslow C, Murphy PJ. Mucins and ocular signs in[7]
symptomatic and asymptomatic contact lens wear. Optom Vis Sci
2008; 85(10): E930-8.
[http://dx.doi.org/10.1097/OPX.0b013e318188896b] [PMID:
18832968]
Uno T, Fukuda M, Ohashi Y, et al. Survey of severe contact lens-[8]
associated microbial keratitis in Japan. Nippon Ganka Gakkai Zasshi
2011; 115(2): 107-15.
[PMID: 21400916]
Sapkota K, Lira M, Martin R, Bhattarai S. Ocular complications of[9]
soft contact lens wearers in a tertiary eye care centre of Nepal. Cont
Lens Anterior Eye 2013; 36(3): 113-7.
[http://dx.doi.org/10.1016/j.clae.2012.11.002] [PMID: 23238170]
Ozkan J, Rathi VM, de la Jara PL, Naduvilath T, Holden BA, Willcox[10]
MD. Effect of daily contact lens cleaning on ocular adverse events
during extended wear. Optom Vis Sci 2015; 92(2): 157-66.
[http://dx.doi.org/10.1097/OPX.0000000000000479] [PMID:
25951477]
Ueda K, Sahashi N, Takahashi Y, Abe E. Adherence of cedar pollen[11]
and the antigen of cedar pollen to soft contact lenses. J Jpn Cont Lens
Soci 2010; 52(2): 127-30.
Mimura T, Fujishima H, Uchio E, et al. Adhesion of pollen particles to[12]
daily disposable soft contact lenses. Clin Optom (Auckl) 2021; 13:
93-101.
[http://dx.doi.org/10.2147/OPTO.S297531] [PMID: 33790684]
Tyler’s quarterly soft contact lens parameter guide. Tyler’s Q soft[13]
contact lens Param Guid. 2019.
Mimura T, Sunaga T, Mizota A. Clinical Academic Topics. Cleaning[14]
effect of hydrogen peroxide solution on cedar pollen attached to
contact lens. (Japanese). Rinsho of Allergy 2020; 40(3): 70-9.
Stapleton F, Stretton S, Papas E, Skotnitsky C, Sweeney DF. Silicone[15]
hydrogel contact lenses and the ocular surface. Ocul Surf 2006; 4(1):
24-43.
[http://dx.doi.org/10.1016/S1542-0124(12)70262-8] [PMID:
16669523]
Precision 1 Lens with Smart Surface Technical File, Alcon Data on[16]
FilePrecision 1 Lens with Smart Surface Technical File. Available at:
https://us.alconscience.com/
Grant T, Tang A. A survey of contact lens wearers and eye care[17]
professionals on satisfaction with a new smart-surface silicone
hydrogel daily disposable contact lens. Clin Optom (Auckl) 2020; 12:
9-15.
[http://dx.doi.org/10.2147/OPTO.S233328] [PMID: 32021532]
Sulley A, Young G, Hunt C. Prospective evaluation of new contact[18]
lens wearer retention rates. Cont Lens Anterior Eye 2018; 41(Suppl.
1): S4.
[http://dx.doi.org/10.1016/j.clae.2018.04.090]
Cummings S, Giedd B, Pearson C. Clinical performance of a new[19]
daily disposable spherical contact lens. Optom Vis Sci 2019; 96
Eabstract 195375.
Thekveli S, Qiu Y, Kapoor Y, Liang W, Pruitt J. Structure-property[20]
relationship of delefilcon A lenses. Cont Lens Anterior Eye 2012;
35(Suppl. 1): e14.
[http://dx.doi.org/10.1016/j.clae.2012.08.044]
© 2021 Mimura et al.
This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is
available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the
original author and source are credited.
... Therefore, the SCL has characteristics that make it difficult for pollen and protein components to adhere to its surface. In fact, our previous paper demonstrated very little pollen adhesion to velofilcon A SCL. 15 This result raises the hypothesis that atmospheric particles, including Asian dust, may also be less likely to adhere to verofilcon A SCL. ...
... In order to understand why Asian dust particles are less likely to adhere to verofilcon A, the results of studies that have investigated the adhesion of pollen to verofilcon were reviewed. 13,15 Basically, SCLs made of silicone hydrogel material are nonionic, so the lens surface is electrically positive or negative zero. Ionic lenses, on the other hand, are charged with negative ions, so they easily attract proteins and stains that are charged with positive ions. ...
... Ionic lenses, on the other hand, are charged with negative ions, so they easily attract proteins and stains that are charged with positive ions. Previous studies have examined the adhesion of pollen particles to different types of contact lenses and the factors involved in particle adhesion to contact lens materials 13,15 The number of particles adhering to the SCL was lowest for delefilcon A and verofilcon A SCLs among the various SCLs. 13,15 The number of adherent pollen particles correlated with the SCL water content, oxygen permeability (Dk), and oxygen transmissibility 13,15 The water content, oxygen permeability, and oxygen transmission rate of verofilcon A are extremely high and meet all these requirements. ...
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