The Visian Implantable Collamer Lens (ICL), a posterior chamber phakic intraocular lens, has been demonstrated to offer effective correction of moderate to high ametropia over a long period of time [
The protocol was registered with the University Hospital Medical Information Network Clinical Trial Registry (000025892). Forty-two eyes of 21 consecutive patients (10 men and 11 women), who underwent implantation of the posterior chamber phakic intraocular lens with a 0.36-mm central hole (hole ICL, KS-Aquaport™; STAAR Surgical, Nidau, Switzerland) for the correction of moderate to high myopia and whose age was 40 years or more, were included in this prospective study. Eyes with keratoconus were excluded from the study by using the screening test of Placido disk videokeratography (TMS-2, Tomey, Nagoya, Japan). We selected toric ICL implantation in eyes with manifest astigmatism of 1.5 diopters (D) or more and nontoric ICL implantation in eyes with that of less than 1.5 D. Preoperatively and 6 months postoperatively, we measured the logarithm of the minimal angle of resolution (logMAR) of monocular distance visual acuity (UDVA) and binocular uncorrected visual acuity at 5.0, 3.0, 2.0, 1.0, 0.7, 0.5, and 0.3-m distances, logMAR corrected distance visual acuity (CDVA), and manifest refraction (spherical equivalent and cylinder), in addition to the usual slit-lamp biomicroscopic and funduscopic examinations. Binocular visual acuity measurements were performed at 5.0, 3.0, 2.0, 1.0, 0.7, 0.5, and 0.3 m with best correction using an all-distance vision tester (AS-15, Kowa, Tokyo, Japan). The patient satisfaction for overall visual performance was assessed at 6 months postoperatively, according to the visual analog scale in a range from 0 (very dissatisfied) to 10 (very satisfied). The study was approved by the Institutional Review Board at Kitasato University School of Medicine and followed the tenets of the Declaration of Helsinki. Informed consent was obtained from all patients after explanation of the nature and possible consequences of the study.
The ICL power was determined by the online calculator of the manufacturer (STAAR Surgical) using a modified vertex formula. We intentionally selected undercorrection of approximately -0.50 to –1.50 D in both eyes as the target refraction, which was individually determined with visual simulation with contact lenses wearing in each patient, based on patient age and patient preference for vision. The ICL size was also chosen by the manufacturer on the basis of the horizontal corneal diameter and the anterior chamber depth measured with scanning-slit topography (Orbscan IIz, Bausch & Lomb, Rochester, NY, USA).
The surgical procedures in our institution were comprised as follows, as described previously [
All statistical analyses were conducted by commercially available statistical software (BellCurve for Excel, Social Survey Research Information Co, Ltd., Tokyo, Japan). The normality of all data samples was first checked by the Shapiro-Wilk test. Since the data did not fulfill the criteria for normal distribution, the Wilcoxon signed-rank test was used for statistical analysis to compare the pre- and postsurgical data. Unless otherwise indicated, the results are expressed as mean ± standard deviation, and a value of p<0.05 was considered statistically significant.
The preoperative and postoperative demographics are listed in Table
Preoperative demographics of the study population undergoing hole implantable collamer lens (hole ICL) implantation.
Characteristic | Mean ± standard deviation |
---|---|
Age (years) | 45.0 ± 3.8 years (range, 40 to 53 years) |
Gender (male : female) | 10 : 11 |
Manifest spherical equivalent (D) | -7.37 ± 3.18 D (range, -2.25 to -14.75 D) |
Manifest cylinder (D) | 1.15 ± 1.36 D (range, 0.00 to 6.00 D) |
LogMAR UDVA | 1.30 ± 0.24 (range, 1.00 to 1.70) |
LogMAR CDVA | -0.17 ± 0.07 (range, -0.30 to 0.00) |
White-to-white distance (mm) | 11.6 ± 0.4 mm (range, 11.0 to 12.3 mm) |
Anterior chamber depth (mm) | 3.04 ± 0.22 mm (range, 2.80 to 3.55 mm) |
D=diopter, logMAR=logarithm of the minimal angle of resolution,
UDVA=uncorrected distance visual acuity, and CDVA=corrected distance visual acuity.
CDVA did not improve significantly, from -0.17 ± 0.07 preoperatively to -0.19 ± 0.08 logMAR postoperatively (p=0.066, Wilcoxon signed-rank test). Twenty-three eyes (55%) showed no change in CDVA, 12 eyes (29%) gained 1 line, 2 eyes (5%) gained 2 lines, and 5 eyes (12%) lost 1 line, 6 months postoperatively (Figure
Changes in corrected distance visual acuity (CDVA) after hole implantable collamer lens (hole ICL) implantation.
UDVA was significantly improved from 1.30 ± 0.24 preoperatively to -0.03 ± 0.20 logMAR postoperatively (p<0.001, Wilcoxon signed-rank test). The cumulative percentages of eyes attaining specified cumulative levels of UDVA are listed in Figure
Cumulative percentages of eyes attaining specified levels of postoperative uncorrected distance visual acuity (UDVA) compared to the cumulative percentages of eyes attaining specified levels of .preoperative corrected distance visual acuity (CDVA) after hole implantable collamer lens (hole ICL) implantation.
Uncorrected visual acuity at near to far distances after hole implantable collamer lens (hole ICL) implantation.
A scatter plot of the attempted versus the achieved manifest spherical equivalent correction, the spherical equivalent refractive accuracy, and the preoperative and postoperative refractive astigmatism are listed in Figures
A scatter plot of attempted versus achieved correction (spherical equivalent) after hole implantable collamer lens (hole ICL) implantation.
Spherical equivalent refractive accuracy after hole implantable collamer lens (hole ICL) implantation.
Preoperative and postoperative refractive astigmatism after hole implantable collamer lens (hole ICL) implantation.
The postoperative satisfaction score was 8.2 ± 1.1 (range: 7 to 10). All patients have been satisfied with overall visual performance after surgery.
Eight (19%) of 42 eyes developed glare or halo in the early postoperative period, but symptoms were mild and no secondary intervention was required. Neither cataract formation, significant intraocular pressure rise, pigment dispersion glaucoma, pupillary block, severe subjective symptoms such as glare or halo, nor any other vision-threatening complications occurred at any time in this series.
In the present study, our preliminary results of undercorrected correction by hole ICL implantation were favorable in all measures of safety, efficacy (especially binocular vision), and predictability, without developing cataract, when used for the correction of moderate to high ametropia. We previously demonstrated that visual performance in ICL-implanted eyes was significantly better than that in post-LASIK eyes, even in the presence of low to moderate myopia [
With regard to the safety, efficacy, and predictability of this surgery, hole ICL implantation was safe and effective and provided predictable results for the correction of moderate to high myopia, findings which were in agreement with previous studies [
With regard to the adverse events of this surgery, it still remains unclear whether hole ICL is effective for the suppression of cataract formation over a long period of time in these presbyopic patients. Gonvers et al. [
We recently showed monovision by hole ICL implantation is beneficial for acquiring overall good binocular visual performance at all distances in early presbyopic subjects [
This study is burdened with at least three limitations. Firstly, the maximum follow-up period was set at 6 postoperative months. Considering that a myopic shift due to nuclear sclerosis of the crystalline lens or elongation of the axial length can occur in high myopic eyes, it may result in a worsening distance visual acuity. Although it is unlikely that the refractive and visual outcomes were markedly changed in the late postoperative period, since it is known that this surgical technique provided stable refractive outcomes in previous studies [
In summary, our pilot study supports the view that intentional undercorrection by hole ICL implantation is clinically useful for acquiring overall good binocular visual performance at all distances (from near to far) in early presbyopic subjects without developing cataract. We believe that this new presbyopic approach may be one of the viable surgical options for early presbyopic subjects.
The authors alone are responsible for the content and writing of the paper.
Dr. Shimizu is a consultant of STAAR Surgical who has assisted with the development of patented technologies. The other authors have declared that no conflicts of interest exist.