Multicenter clinical outcomes of hole implantable collamer lens implantation in middle-aged patients

Abstract

To assess the multicenter clinical outcomes of the implantation of hole implantable collamer lens (Hole ICL, ICL KS-AquaPORTTM; STAAR Surgical, Nidau, Switzerland) in patients of 45 years or more. We retrospectively assessed the surgery’s safety, efficacy, predictability, stability, and adverse events before surgery and after the surgery at 1 week; 1, 3, and 6 months; and 1 year, followed by once every year for approximately 2.2 years. A total of 118 eyes of 65 patients aged 45–65 years with myopic refractive errors ranging from − 2.13 to − 18.75 diopters (D) underwent hole ICL implantation and routine postoperative examinations. The average observation period was 2.2 ± 1.0 years. The safety and efficacy indices were 1.08 ± 0.21 and 0.87 ± 0.25, respectively. Manifest refraction changes of − 0.20 ± 0.43 D occurred from 1 month to the final visit after ICL implantation. Eight eyes (6.8%) developed asymptomatic anterior subcapsular cataract (ASC) immediately after surgery, and three eyes (2.5%) developed clinically significant symptomatic nuclear cataracts during the follow-up period. According to our experience, hole ICL implantation offered favorable outcomes in all measures of safety, efficacy, predictability, and stability, even in middle-aged patients, during the 2.2-year observation period.

Full text

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Multicenter clinical outcomes
of hole implantable collamer
lens implantation in middle‑aged
patients
Akihito Igarashi1*, Kazutaka Kamiya2, Kazuo Ichikawa3, Yoshihiro Kitazawa4,
Takashi Kojima5, Tomoaki Nakamura6 & Kimiya Shimizu1
To assess the multicenter clinical outcomes of the implantation of hole implantable collamer lens
(Hole ICL, ICL KS‑AquaPORTTM; STAAR Surgical, Nidau, Switzerland) in patients of 45 years or
more. We retrospectively assessed the surgery’s safety, ecacy, predictability, stability, and adverse
events before surgery and after the surgery at 1 week; 1, 3, and 6 months; and 1 year, followed by
once every year for approximately 2.2 years. A total of 118 eyes of 65 patients aged 45–65 years with
myopic refractive errors ranging from − 2.13 to − 18.75 diopters (D) underwent hole ICL implantation
and routine postoperative examinations. The average observation period was 2.2 ± 1.0 years. The
safety and ecacy indices were 1.08 ± 0.21 and 0.87 ± 0.25, respectively. Manifest refraction changes
of − 0.20 ± 0.43 D occurred from 1 month to the nal visit after ICL implantation. Eight eyes (6.8%)
developed asymptomatic anterior subcapsular cataract (ASC) immediately after surgery, and three
eyes (2.5%) developed clinically signicant symptomatic nuclear cataracts during the follow‑up
period. According to our experience, hole ICL implantation oered favorable outcomes in all measures
of safety, ecacy, predictability, and stability, even in middle‑aged patients, during the 2.2‑year
observation period.
e posterior chamber phakic intraocular implantable collamer lens (ICL) with a central port (Hole ICL, ICL
KS-AquaPORT, STAAR Surgical, Nidau, Switzerland) was rst implanted by Kimiya Shimizu in 20071, and the
number of ICL surgeries has signicantly increased since then due to improved safety. e conventional ICL
(before V4 models) had two major problems: (1) Iridectomy was required because the ICL interfered with the
intraocular aqueous circulation, and if the iridectomy was incomplete, pupillary block occurred in rare cases2.
(2) Risk of metabolic cataract progression due to poor circulation of aqueous humor, particularly in cases with
low vault (< 230μm)3, high levels of myopia4, and an advanced age (over 40years old)4.
When compared to conventional ICLs (V4 and earlier models), hole ICL has a 0.36-mm hole in the center
of the lens, which is designed to allow the aqueous humor in the eye to circulate naturally. erefore, the above-
mentioned complications of conventional ICL have signicantly improved5. Due to the risk of cataracts and
presbyopia in conventional ICL, the surgical indication for ICL in Japan is 21–45years of age. However, there are
patients aged over 45years who wish to undergo ICL surgery. Since the extended depth of focus ICL (EVO Viva,
STAAR Surgical, Nidau, Switzerland) also obtained the CE mark in July 2020, it is expected that the number of
patients aged ≥ 45years will be increasing further in the future. erefore, in this multicenter study, we evaluated
the safety and ecacy of the clinical outcomes aer hole ICL implantation in patients aged ≥ 45years in Japan.
Results
Study population. Preoperative patient demographics are summarized in Table1. All patients were fol-
lowed up for more than 1year, and the observation period was 2.2 ± 1.0years (range 1–3years).
OPEN
1Department of Ophthalmology, Sanno Hospital, 8-10-16 Akasaka, Minato-ku, Tokyo 107-0052, Japan. 2Visual
Physiology, School of Allied Health Sciences, Kitasato University, Kanagawa, Japan. 3Chukyo Eye Clinic, Aichi,
Nagoya, Japan. 4Sapia-Tower Eye Clinic, Tokyo, Japan. 5Department of Ophthalmology, Keio University School of
Medicine, Tokyo, Japan. 6Nagoya Eye Clinic, Aichi, Nagoya, Japan. *email: iki0478@yahoo.co.jp
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Safety outcomes. e log MAR CDVA at 1week, 1month, 3months, 1year, and the nal visit (average:
2.2years) aer surgery was − 0.18 ± 0.08, − 0.18 ± 0.09, − 0.18 ± 0.10, − 0.017 ± 0.09, and 0.17 ± 0.09, respectively.
e safety index (mean postoperative CDVA/ mean preoperative CDVA) at 1week, 1month, 3months, 1year,
and the nal visit aer surgery was 1.10 ± 0.24, 1.10 ± 0.23, 1.11 ± 0.22, 1.08 ± 0.22, and 1.08 ± 0.21, respectively.
At the nal visit, 62 eyes (52.5%) showed no change in CDVA, 38 eyes (32.2%) gained one line, 1 eye (0.8%)
gained two lines, 17 eyes (14.4%) lost one line, and no eye (0%) lost two or more lines.
Eectiveness outcomes. To evaluate the ecacy of the procedure, we evaluated eyes in which the tar-
get refraction was emmetropia (N = 73 eyes). e log MAR UDVA at 1week, 1month, 3months, 1year, and
the nal visit (average: 2.2years) aer surgery was − 0.10 ± 0.18, − 0.10 ± 0.17, − 0.10 ± 0.17, − 0.09 ± 0.16, and
− 0.07 ± 0.17, respectively. e ecacy index (mean postoperative UDVA/ mean preoperative CDVA) was
0.95 ± 0.29, 0.94 ± 0.28, 0.93 ± 0.28, 0.91 ± 0.26, and 0.87 ± 0.25 at 1week, 1month, 3months, 1year, and the nal
visit aer surgery, respectively. At 1week, 1month, 3months, 1year, and the nal visit aer surgery, 96%, 97%,
96%, 96%, and 96% of eyes, respectively, had UDVAs of 20/40 or better, and 90%, 88%, 90%, 89%, and 86% of
eyes, respectively, had UDVAs of 20/20 or better.
Predictability. At 1week, 1month, 3months, 1year, and the nal visit (average: 2.2years) aer surgery,
80%, 82%, 83%, 80%, and 78% of eyes, respectively, were within ± 0.5 D, and 94%, 96%, 93%, 97%, and 93% of
eyes, respectively, were within ± 1.0 D of the attempted correction (Fig.1).
Table 1. Preoperative demographics of the study population. Log MAR logarithm of the minimal angle of
resolution, UDVA uncorrected distance visual acuity, CDVA corrected distance visual acuity.
Characteristic Mean ± SD
Observation period (years) 2.2 ± 1.0years (range 1 to 3years)
Age (years) 48.9 ± 4.2years (range 45 to 65years)
Gender (% female) 47.5%
Manifest spherical equivalent (D) − 9.15 ± 3.59 D (range − 2.13 to − 18.75 D)
Manifest cylinder (D) 1.11 ± 1.25 D (range 0.00 to 6.00 D)
Log MAR UDVA 1.41 ± 0.26 (range 0.52 to 2.00 )
Log MAR CDVA − 0.15 ± 0.10 (range − 0.30 to 0.22 )
White-to-white distance (mm) 11.7 ± 0.4mm (range 10.9 to 12.8mm)
Anterior chamber depth (mm) 2.99 ± 0.27mm (range 2.51 to 4.19mm)
Mean keratometric readings (D) 43.9 ± 1.4 D (range 39.6 to 47.1 D)
Central cornea thickness (μm) 541 ± 39μm (range 452 to 651μm)
Intraocular pressure (mmHg) 13.6 ± 2.5mmHg (range 8 to 21mmHg)
Endothelial cell density (cells/mm2)2752 ± 263 cells/mm2 (range 2153 to 3401 cells/mm2)
Figure1. Percentages of eyes within ± 0.5 and ± 1.0 D of the attempted correction (spherical equivalent) aer
hole implantable collamer lens (ICL) implantation.
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Stability. At 1week, 1month, 3months, 1year, and the nal visit (average: 2.2years) aer surgery, the mean
manifest spherical equivalent was − 0.35 ± 0.69, − 0.40 ± 0.65, − 0.37 ± 0.68, − 0.48 ± 0.68, and − 0.61 ± 0.71 D,
respectively (ANOVA, p = 0.03). Multiple comparisons revealed signicant dierences between measurements
made at 1week aer surgery and at the nal visit aer surgery (Tukey–Kramer test, p = 0.03). e changes in
manifest refraction from 1month to 1year and from 1month to the nal visit were − 0.06 ± 0.31 and − 0.20 ± 0.43
D, respectively.
Intraocular pressure. e IOP showed no signicant change from 13.6 ± 2.5mmHg before the surgery
to 14.1 ± 3.2, 13.4 ± 2.4, 13.4 ± 2.6, 13.9 ± 2.8, and 13.9 ± 3.1mmHg at 1week, 1month, 3months, 1year, and
the nal visit (average: 2.2years) aer surgery, respectively (ANOVA, p = 0.21). No signicant increase in IOP
occurred in any case during the observation period.
Endothelial cell density. e endothelial cell density signicantly decreased from 2752 ± 263cells/mm2
preoperatively to 2700 ± 260 cells/mm2 at the nal visit (average: 2.2 years) postoperatively (Paired t-test,
p = 0.01). e mean percentage of endothelial cell loss was1.6 ± 8.1% (range from − 28.0 to + 25.6%) at the nal
visit (2.2years postoperatively).
Secondary surgeries/adverse events. ere were no intraoperative complications, and all implanta-
tions were uneventful. Of the 118 eyes examined, 8 eyes (6.8%) developed asymptomatic anterior subcapsular
cataract (ASC), but all eyes had a CDVA of 20/20 or better (Table2). In most cases, ASCs occurred immedi-
ately aer surgery. Case 1 developed ASC immediately aer ICL exchange due to an excessive high vault. ASC
occurred under the hole position of the ICL (Fig.2), possibly due to the excessive suction of the ophthalmic
viscosurgical device between the ICL and the crystalline lens through this hole using an irrigation and aspiration
tip. e ASC may have been caused due to the contact between the ICL and the anterior surface of the lens dur-
ing irrigation and aspiration. However, the ASC did not progress thereaer. Only three eyes (2.5%) developed
clinically signicant nuclear cataracts postoperatively, and these patients complained of poor visibility (double
vision and myopic change) (Fig.3). Simultaneous lens extraction and phacoemulsication with intraocular lens
(IOL) implantation were successfully performed in these three eyes, and the patients had improved vision and
no other complaints aer the surgery. All eyes had high myopia (long axial length) (Table3). In Table3, Case 1
Table 2. Asymptomatic anterior subcapsular cataracts (ASC) cases aer Hole implantable collamer lens (ICL)
implantation. SE spherical equivalent, CDVA corrected distance visual acuity, CT corneal thickness.
Case 1 Case 2 Case 3 Case 4 Case 5 Case 6
Right eye Le eye Le eye Le eye Right eye Right eye Le eye Right e ye
Age 50 50 59 54 46 53 53 47
Gender Female Female Female Female Female Male Male Male
Time of onset Immediately aer
surgery (ICL
exchange)
Immediately aer
surgery (ICL
exchange)
Immediately aer
surgery Immediately aer
surgery Immediately aer
surgery Immediately aer
surgery Immediately aer
surgery Post-Op
6months
Pre. SE (D) − 6.1 − 6.5 − 18.3 − 11.6 − 14.8 − 16.0 − 12.5 − 13.3
Pre. CDVA 30/20 30/20 20/20 12/20 40/20 24/20 20/20 24/20
CDVA (Final
Visit) 20/20 (2years) 20/13 (2years) 20/16 (1year) 20/25 (1year) 20/13 (3years) 20/16 (2years) 20/16 (2years) 20/13 (3years)
Vault (CT) 0.6 0.4 0.6 0.7 1.0 0.5 0.3 0.6
Figure2. Asymptomatic anterior subcapsular cataract (ASC) cases aer hole implantable collamer lens (ICL)
implantation.
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underwent binocular cataract surgery with a dierence of a few years. e le eye in Case 2 was not indicated for
ICL implantation because of a previous history of optic neuritis and poor corrected visual acuity. Subsequently,
Case 2 underwent cataract surgery in both eyes at the same time. Of the 46 cases in which toric ICL was used,
deteriorating UDVA, changing refraction, or an axis rotation of 10° or more occurred in two eyes (4.3%) post-
operatively, which required ICL repositioning. ree eyes (2.5%) underwent ICL exchange due to excessive high
vault. No pigment dispersion glaucoma, pupillary block, or any other vision-threatening complications were
seen throughout the follow-up period. Table4 shows the clinical outcomes based on each target refractive power.
e results were divided into three target refractive power categories, with no signicant dierences in the safety
and the predictability metrics.
Discussion
In this multicenter study, we conrmed excellent results in all measures of safety, ecacy, predictability, and sta-
bility of hole ICL implantation in patients older than 45years throughout the follow-up period of 1year or more.
Conventional ICLs (before V4 models) have been reported to have good long-term clinical outcomes9–12.
However, conventional ICL has two drawbacks. One is the need for iridectomy, and the other is the progression
of ASC aer ICL implantation. Inappropriate iridectomy rarely resulted in pupillary block2. e incidence of
ASC ranged from 1.1 to 5.9%5, and the probability of requiring cataract surgery for vision loss ranged from 0
to 1.8%5. e risk of cataract progression was particularly high in patients with an advanced age (over 40years
old)4, high myopia (less than − 12.0 D)4, and low vault (< 230μm)3. However, with the advent of the hole ICL,
these risks have been greatly reduced and safety has been improved13.
A meta-analysis of hole ICL13 reported a safety index of 1.15 (range: 1.01–1.42, average follow-up period:
13.2months) and that only 0.2% of eyes lost two or more lines of CDVA, while 95.5% maintained or gained
lines of CDVA; the change in CDVA before and aer surgery was also good. To date, only one case of pupillary
Figure3. Nuclear cataract cases aer hole implantable collamer lens (ICL) implantation.
Table 3. e cases of ICL extraction and cataract surgery aer Hole implantable collamer lens (ICL)
implantation. CDVA corrected distance visual acuity, SE spherical equivalent, CT corneal thickness.
Case 1 Case 2
Right eye Le eye Right eye
Age 46 46 52
Gender Male Male Female
Pre. CDVA 40/20 30/20 24/20
Pre. SE (D) − 12.3 − 13.0 − 11.8
Pre. vault (CT) 0.7 1.3 1.1
Pre. axial length (mm) 30.1 30.2 27.5
Time to cataract surgery 4.3years 2.1years 2.9years
CDVA (nal visit) 24/20 20/20 20/20
SE (D) − 0.25D − 2.50D − 1.75D
Types of cataracts Nuclear Nuclear Nuclear
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block has been reported aer hole ICL implantation14, but this case was unique in that the central port of the
ICL was blocked with viscoelastic and inammatory debris. Visually signicant cataract has not been reported
in patients implanted with hole ICL13. e incidence of asymptomatic ASC opacities was 0.49%, but none of the
reports had any cases of ICL removal and cataract surgery because of vision loss13.
In this multicenter study, the patients were aged 45years or older and were at a high risk of developing cataract
with conventional ICL4. ere are only a few reports6–8 on the postoperative outcomes aer hole ICL implantation
in middle-aged and older patients, which are summarized in Table5. All previous reports6–8 had short observa-
tion periods and small sample sizes. In this study, the mean observation period was 2.2years (cases with more
than 1year of follow-up), and the safety index was 1.08. None of the eyes lost two or more lines of CDVA, and
85.6% maintained or gained lines of CDVA. is multicenter study demonstrated a 6.8% (8/118) incidence of
secondary surgical intervention with an average follow-up period of 2.2years. Two eyes required rotation of a
toric ICL, and three eyes exchanged the ICL due to excessive high vault (> 1000μm). ree eyes (2.5%) developed
clinically signicant nuclear cataracts postoperatively, and simultaneous lens extraction and phacoemulsication
with IOL implantation were successfully performed. ese three eyes also had preoperative mild cataracts of
G1.5 to G2 (Emery–Little classication). All cases of nuclear cataract had CDVA > 20/20, but cataract surgery
was performed due to decreased UDVA. e prediction of IOL power for cataract surgery in ICL implanted eyes
is good15, and the patients are also satised with their vision. All patients with nuclear cataracts in this study had
high myopia with an axial length of ≥ 27.5mm, which may have inuenced the results16.
Asymptomatic ASC opacities occurred in 6.8% (8/118) of cases. is is a high rate compared to previous
reports17–19, but seven eyes developed ASC opacities immediately aer surgery. In these cases, the ASC was
localized just below the central port of the lens, suggesting that it was caused by an intraoperative irrigation
technique. e suction hole was vigorously directed toward the central hole during irrigation and aspiration, and
we thought that the ASC was caused by the contact of the anterior surface of the lens with the posterior surface of
the ICL during aspiration. Steinwender etal.20 reported similar cases and noted that aer changing the surgical
technique to a very gentle irrigation and keeping the cannula near the main incision, more than 90 phakic IOL
implantations were performed in the clinic during a follow-up period of 14months, with no further occurrence
of ASC. is may imply that ASC can easily occur by mechanical contact with the lens in older patients, since
no ASCs have been observed in young patients using this technique. In this study, patients with asymptomatic
ASC opacities did not have ASC progression or CDVA decline and did not require additional surgery.
As a limitation to this study, we believe that a longer follow-up is necessary. In addition, we could not measure
the objective postoperative vault because not all hospitals had anterior segment optical coherence tomography.
Table 4. Clinical outcomes by target refractive power. UDVA uncorrected distance visual acuity, CDVA
corrected distance visual acuity, SE spherical equivalent, DE dominant eye, NDE non-dominant eye.
Pre-UDVA Pre-CDVA Pre-SE (D) Target ref (D) Post-UDVA Safety index Ecacy index Post-SE (D) Predictability
(± 1.0D)
Bilateral
Emmetropia
(N = 54eyes) 1.38 ± 0.27 − 0.15 ± 0.11 − 9.14 ± 3.70 − 0.10 ± 0.19 − 0.07 ± 0.18 1.11 ± 0.22 0.88 ± 0.26 − 0.40 ± 0.57 93%
Monovision
(N = 26eyes
DE:13/NDE:13)
DE 1.37 ± 0.22
NDE: 1.44 ± 0.24
DE: − 0.16 ± 0.06
NDE:
− 0.16 ± 0.07
DE: − 8.05 ± 3.65
NDE:
− 8.55 ± 3.84
DE: − 0.31 ± 0.24
NDE:
− 1.14 ± 0.41
DE:
− 0.03 ± 0.21
NDE:
0.21 ± 0.32
DE: 1.09 ± 0.17
NDE:
1.06 ± 0.18
DE: 0.80 ± 0.24
NDE:
0.52 ± 0.30
DE: − 0.37 ± 0.42
NDE:
− 1.10 ± 0.73
DE: 100% NDE:
100%
Bilateral
Intentional-
Undercorrection
(N = 26eyes)
1.46 ± 0.20 − 0.16 ± 0.09 − 10.17 ± 2.94 − 0.78 ± 0.33 0.08 ± 0.22 1.02 ± 0.20 0.65 ± 0.29 − 0.80 ± 0.63 92%
Table 5. e reports on Hole implantable collamer lens (ICL) implantation in patients over 40 years of age.
UDVA uncorrected distance visual acuity, CDVA corrected distance visual acuity, SE spherical equivalent,
endothelial cell density, DE dominant eye, NDE non-dominant eye, ASC anterior subcapsular cataract, NC
nuclear cataract, Log MAR logarithm of the minimal angle of resolution.
Author
Observation
period (number
of cases) Age (min, max) UDVA (log MAR) CDVA (log MAR) ± 1.0D (% of
eyes) Post.op SE (D) ECD (cells/mm2)
(% of loss) Cataract
Tañá-Rivero etal.61year (33 eyes) 43.5 ± 4.5 (40, 56) 0.88 ± 0.16 (deci-
mal) 0.96 ± 0.09 (deci-
mal) 93.9 − 0.09 ± 0.47 2516 ± 234 (2.04) 0%
Kamiya etal.76months (34 eyes) 46.1 ± 4.2 (40, 53) − 0.04 ± 0.18 − 0.19 ± 0.09 100 DE: − 0.08 ± 0.17
NDE: − 0.65 ± 0.29 – 0%
Takahashi etal.86months (42 eyes) 45.0 ± 3.8 (40, 53) − 0.03 ± 0.20 − 0.19 ± 0.08 100 – – 0%
Current study 2.2years (118
eyes) 48.9 ± 4.2 (45, 65) −0.07 ± 0.17 − 0.17 ± 0.09 93 − 0.61 ± 0.71 2700 ± 260 (1.6)
6.8%: Asympto-
matic ASC cases
2.5%: Sympto-
matic NC cases
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Further, we included some cases with shallow anterior chamber depth (> 2.5mm) based on previous reports21.
In the future, we believe that a more detailed investigation of the relationship between ICL size and postopera-
tive complications is desirable.
In conclusion, this multicenter study supports the view that hole ICL implantation oered good results in all
measures of safety, ecacy, predictability, and stability in patients over 45years old during the 2.2-year observa-
tion period. However, we must be careful of mechanical lens contact associated with intraoperative manipulation
in older patients. In addition, since nuclear cataracts may occur with aging in patients with severe myopia, prior
explanation is important. e number of ICL surgeries in middle-aged and elderly patients is expected to increase
in the future, and we hope that the results of this study will be of help to these patients.
Methods
is was a multicenter study performed at Kitasato University, Nagoya Eye Clinic, Sapia Tower Eye Clinic, and
Sanno Hospital in Japan. A total of 118 eyes of 65 consecutive patients (males: 62eyes and females: 56 eyes) who
underwent implantation of hole ICL for the correction of myopia and myopic astigmatism and regularly returned
for postoperative examination were included in this retrospective observational study. In this study, 106 eyes
of 53 patients were operated on both eyes, and 12 eyes were operated on only one eye. e inclusion criteria for
this surgical technique were as follows: unsatisfactory correction with spectacles or contact lenses, ≥ 45years of
age, stable refraction for at least 6months, myopia ranging from − 2.0 to − 20.0 diopters (D), anterior chamber
depth ≥ 2.5mm, endothelial cell density ≥ 2000 cells/mm2, no history of ocular surgery, progressive corneal
degeneration, cataract, glaucoma or uveitis, and follow-up of ≥ 1year. Eyes with keratoconus were excluded from
the study by using the keratoconus screening test of Placido disk videokeratography (TMS-2, Tomey, Nagoya,
Japan). Before surgery, the horizontal white-to-white distance and anterior chamber depth (from the corneal
endothelium to the anterior surface of the lens) were measured using a scanning-slit topograph (Orbscan IIz,
Bausch & Lomb, Rochester, US), and the axial length was measured using partial coherence laser interferometry
(IOL Master; Carl Zeiss AG, Oberkochen, Germany). Before surgery and 1day; 1week; 1, 3, and 6months; and 1,
2, and 3years aer surgery, we determined the following: logarithm of the minimal angle of resolution (log MAR)
of uncorrected distance visual acuity (UDVA), log MAR of corrected distance visual acuity (CDVA), manifest
refraction (spherical equivalent), intraocular pressure (IOP), endothelial cell density, mean keratometric reading,
and axial length, in addition to the usual slit-lamp biomicroscopic and fundoscopic examinations. e size of
ICL was selected based on the nomogram provided by the manufacturer (STAAR Surgical).
e study was approved by the Institutional Review Board of International University of Health and Welfare
(21-S-10) and followed the tenets of the Declaration of Helsinki. Written informed consent was obtained from
all patients aer explanation of the nature and possible consequences of the study.
Implantable collamer lens power calculation. ICL power calculation was performed by the manu-
facturer (STAAR Surgical) using a modied vertex formula. In this study, we set the target refractive power
taking presbyopia into account, as described previously6–8. e target refractive power was emmetropia in 50.9%
(54/106), monovision in 24.5% (26/106), and intentional under-correction in 24.5% (26/106). e target refrac-
tive power was individually determined by contact lens simulation and the patient’s lifestyle. ese groupings by
the target refractive power were individually performed by each case in which both eyes were operated.
Implantable collamer lens surgical procedure. All ICL implantation surgeries were performed using
a standardized method in all surgical centers. Aer topical anesthesia, ICL was inserted through a 3-mm clear
corneal incision using an injector cartridge (STAAR Surgical) aer placement of a viscosurgical device (Opegan;
Santen, Osaka, Japan) into the anterior chamber. e ICL was placed in the posterior chamber, the viscosurgical
device was completely washed out of the anterior chamber with a balanced salt solution, and a myotic agent was
instilled. All surgeries were uneventful, and no intraoperative complication was observed. Aer surgery, steroids
(0.1% betamethasone; Rinderon; Shionogi, Osaka, Japan) and antibiotics (0.3% levooxacin; Cravit; Santen,
Osaka, Japan) were topically administered four times daily for two weeks, and the dose was gradually reduced
thereaer.
Statistical analysis. All statistical analyses were performed using StatView version 5.0 (SAS, Cary, NC,
USA). One-way analysis of variance (ANOVA) was used to analyze the time course of changes, along with the
Tukey–Kramer test for multiple comparisons. e paired t-test was used to compare the pre- and post-surgical
data. e Pearson correlation coecient was used to assess the correlation between the changes in manifest
spherical equivalent and axial length. e results are expressed as mean ± standard deviation, and a value of
p < 0.05 was considered statistically signicant.
Received: 27 December 2021; Accepted: 1 March 2022
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Author contributions
All authors compiled the data from each institution and prepared the paper in A.I. and K.K.Finally, K.S. super-
vised the paper.
Competing interests
Dr. Shimizu is a consultant to STAAR Surgical. e remaining authors indicate no nancial conict of interest.
Additional information
Correspondence and requests for materials should be addressed to A.I.
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