·Clinical Research·
The
effects of implantable collamer lens implantation on higher order aberrations
Belma Kayhan1,2, Efekan Coskunseven1,
Onurcan Sahin1,3, Ioannis Pallikaris1,3
1Dunyagoz Hospital Group, Istanbul
34337, Turkey
2Department of Ophthalmology, Sultan
Abdulhamid Han Training and Research Hospital, the University of Saglik
Bilimleri, Istanbul 34668, Turkey
3Institute of Vision and Optics,
University of Crete, Heraklion 70013, Greece
Correspondence to: Belma Kayhan. Department of Ophthalmology,
Sultan Abdulhamid Han Training and Research Hospital, Tibbiye Street, Selimiye,
Uskudar, Istanbul 34668, Turkey. drbelmakayhan@gmail.com
Received:
Abstract
AIM: To evaluate
the changes in higher order aberrations (HOAs) after implantable collamer lens
(ICL; Staar Surgical, Nidau, Switzerland) implantation.
METHODS: Totally 30 eyes of 18 patients with myopia were included in
this study with an average age of 25.77y (min: 21, max: 40). Refraction,
uncorrected distance visual acuity (UDVA), corrected distance visual acuity
(CDVA), HOAs (entire, corneal and internal) were evaluated preoperatively and
three months postoperatively. Ocular aberrations were measured by using iTrace
(Tracey Technology, Houston, Texas, USA). SPSS
(IBM Corp. Released 2013. IBM SPSS Statistics for Windows, Version 22.0.
Armonk, NY: IBM Corp) was used for the statistical analysis and the
interpretation of the data. P values
of less than 0.05 were considered statistically significant.
RESULTS: The preoperative mean spherical power was -9.01 D (min: -5.00, max:
-13.00) and the mean cylindrical error was -2.40 D (min: -0.50, max: -4.75).
The postoperative mean residual spherical power was -0.73 D (min: -0.20, max:
-1.75) and the mean cylindrical error was -0.89 D (min: -0.18, max: -2.09). Analyses were made on root mean
square (RMS) values of total HOAs (tHOAs), spherical aberration, coma and
trefoil as entire, corneal and internal components. The differences in entire
tHOAs and in internal tHOAs were significant. There was no significant change
found in spherical aberrations. The differences in entire coma and in internal
coma were significant. There was no significant change found in corneal coma.
With respect to trefoil, the only significant difference was in internal
trefoil.
CONCLUSION: The ICL implantation corrects the refractive error
successfully and changes entire and internal HOAs of the eye.
KEYWORDS: implantable collamer lens; myopia;
aberrations
DOI:10.18240/ijo.2019.12.05
Citation: Kayhan B, Coskunseven E, Sahin O,
Pallikaris I. The effects of implantable collamer lens implantation on higher
order aberrations. Int J Ophthalmol 2019;12(12):1848-1852
INTRODUCTION
Uncorrected refractive error is the
leading cause of visual impairment in the world[1].
Studies revealed that the prevalence of myopia continues to increase[2]. Therefore, the treatment of this refractive error is
very important. Corneal refractive surgery is the most preferred treatment for
the low and moderate myopia. However, the high myopia and the moderate myopia
with corneas which are not suitable for corneal refractive surgery because of
thickness and/or keratometric values, can be treated with the phakic
intraocular lens (IOL) implantation. The popularity of the phakic IOLs is
increasing as many studies have shown very good refractive outcomes,
predictability and safety[3-6].
Visian implantable collamer lens (ICL; Staar Surgical, Nidau, Switzerland) is
the widely used posterior chamber phakic IOL which is also approved by the Food
and Drug Administration (FDA).
Several studies reported that higher
order aberrations (HOAs) play a major role in the visual quality[7-11]. In the evaluation of the
outcomes of the refractive treatments, correction of refractive error and
changes of HOAs have been taken into consideration for satisfaction. These data
led to customized corneal refractive treatments such as wavefront-guided,
wavefront-optimized ablations to induce lower HOAs. With ICL implantation, we
add a new optical component to internal optics of the eye. While this new
component changes the refraction of the eye, it probably changes other optical
properties of the visual system. By using Ray Tracing technology (iTrace,
Tracey Technology, Houston, Texas, USA), we are able to measure entire eye
aberrations, corneal aberrations and internal aberrations, which are obtained
by subtracting corneal aberrations from entire eye aberrations. In this study,
we aimed to investigate the effects of ICL implantation on HOAs of cornea,
internal ocular optics as well as entire eye, by applying Ray Tracing
technology.
SUBJECTS AND METHODS
Ethical Approval This retrospective study was
conducted in accordance with the Declaration of Helsinki (2008) and was
approved by the Institutional Ethics Review Committee of Dunyagoz Hospital
Group. Written informed consent was obtained from all participating
individuals.
This retrospective study comprised
30 eyes of 18 patients which underwent ICL implantation for myopia at Dunyagoz
Etiler Hospital, Istanbul, Turkey, in 2016. Both eyes of 12 patients and one
eye of 6 patients (3 eyes were right, 3 eyes were left) were included in the
study. The data were obtained preoperatively and 3mo after the operation.
Preoperative ophthalmic examinations consisted of detailed medical history,
manifest and cycloplegic refractions, uncorrected distance visual acuity (UDVA)
and corrected distance visual acuity (CDVA) measurements by using Snellen
chart, anterior segment examination with slit-lamp biomicroscopy and detailed
fundus examination. In addition to these routine examinations, Orbscan (Bausch
& Lomb, Rochester, New York, USA) was used for corneal topographic,
horizontal white to white (WTW) distance and anterior chamber depth (ACD)
measurements. The SP 3000P specular microscope (Topcon Corporation, Tokyo,
Japan) was used for endothelial cell count. Corneal thickness was measured by
Pentacam (Oculus Optikgeräte, Wetzlar, Germany).
The inclusion criteria of the study
were the age older than 21 years old, stable refraction at least 1y,
endothelial cell count of greater than 2400 endothelial cells/mm2,
no iris abnormality and no pupil dysfunction, ACD greater than
Ocular aberrations were measured by
using iTrace (Tracey Technology, Houston, Texas, USA) before surgery and three
months after surgery by the same person. Zernike coefficients in
The STAAR Surgical Customer Service
Department formula was used to calculate the ICL power. ACD calculated from the
corneal endothelium, central corneal thickness, mean corneal keratometry,
refraction measured
Nd:YAG laser peripheral iridotomies
were done 1d before ICL implantation as the surgeon preferred this timing to
clean the iris particules during surgery with anterior chamber washing. The 11-
and 1-o’clock positions in the iris were chosen for iridotomies which were 0.5
to
All surgeries were performed by the
same surgeon (Coskunseven E). The operations were performed under general
anesthesia with the same disinfecting, draping, and eye stabilizing techniques
of cataract surgery. Two side port incisions were made and cohesive ophthalmic
viscosurgical device of sodium hyaluronate 1.0% was injected. A
Statistical Analysis SPSS (IBM
Corp. Released 2013. IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY:
IBM Corp) was used for the statistical analysis and the interpretation of the
data. Kolmogorov-Smirnov and Shapiro-Wilk test for testing the normal
distribution and Levene’s test for testing the equality of variances were used.
Furthermore, two-tailed paired samples t-test (For normally distributed
data) and Wilcoxon signed rank test (Not normally distributed data) were
applied for analyses differences for the comparison of the results across the
pre and the post operation. P values of
less than 0.05 were considered statistically significant.
RESULTS
The preoperative mean spherical
power was -9.01 D (min: -5.00, max: -13.00, SD: 2.18) and the mean cylindrical
error was -2.40 D (min: -0.50, max: -4.75, SD: 1.22). The postoperative mean
residual spherical power was -0.73 D (min: -0.20, max: -1.75, SD: 0.48) and the
mean cylindrical error was -0.89 D (min: -0.18, max: -2.09, SD: 0.50). The mean
difference of spherical power was 8.72 D and the difference was statistically
significant (t=21.69, P<0.001). The mean difference of
cylindrical power was 1.51 D and the difference was statistically significant (t=6.63,
P<0.001).
Visual acuity was recorded as
decimal units. The mean preoperative UDVA was 0.05 (range 0.025 to 0.1) and the
mean postoperative UDVA was 0.8 (range 0.5 to 1.0). At the 3rd
month, 93% of patients had a UDVA of 0.6 or better and 46% had 0.8 or better.
The mean preoperative CDVA was 0.8 (0.4 to 1.0) and the mean postoperative CDVA
was 0.9 (range 0.6 to 1.0). At the 3rd month, 90% of patients had a
CDVA of 0.8 or better and 56% had 1.0 or better (Figure 1).
Figure 1 Thirty eyes (plano target)
3mo postoperative UDVA.
Analyses of HOAs were made on root
mean square (RMS) values of total HOAs (tHOAs), spherical aberration, coma and
trefoil as entire, corneal and internal components. The differences in entire
tHOAs and in internal tHOAs were significant. There was no significant change
found in corneal tHOAs (Table 1).
Table 1 tHOAs
|
Parameters |
Entire tHOAs Preop./3rd month |
Corneal tHOAs Preop./3rd month |
Internal tHOAs Preop./3rd month |
|
Paired
samples statistics |
|
|
|
|
Mean |
0.159/0.097 |
0.064/0.079 |
0.165/0.107 |
|
n |
30/30 |
30/30 |
30/30 |
|
SD |
0.095/0.038 |
0.032/0.069 |
0.088/0.056 |
|
Standart error mean |
0.017/0.007 |
0.006/0.013 |
0.016/0.010 |
|
Correlation |
0.370 |
0.064 |
0.430 |
|
Significance |
0.044 |
0.736 |
0.018 |
|
Paired
samples test |
|
|
|
|
Mean difference |
0.062 |
-0.014 |
0.058 |
|
t |
3.824 |
-1.066 |
3.893 |
|
Degrees of freedom |
29 |
29 |
29 |
|
Significance (2-tailed) |
0.001 |
0.295 |
0.001 |
tHOAs: Total higher order
aberrations; SD: Standard
deviation.
There were no statistically
significant differences between the spherical aberration values. The difference
between total spherical aberrations was 0.01 (P>0.112), corneal
spherical aberrations 0.0009 (P>0.689), internal spherical aberrations
0.001 (P>0.806) respectively. The differences in entire coma and in
internal coma were significant. There was no significant change found in
corneal coma (Table 2).
Table 2 Coma
|
Parameters |
Entire coma Preop./3rd month |
Corneal coma Preop./3rd month |
Internal coma Preop./3rd month |
|
Paired
samples statistics |
|
|
|
|
Mean |
0.091/0.052 |
0.034/0.045 |
0.120/0.061 |
|
n |
30/30 |
30/30 |
30/30 |
|
SD |
0.075/0.032 |
0.022/0.038 |
0.158/0.046 |
|
Standart error mean |
0.014/0.006 |
0.004/0.007 |
0.029/0.008 |
|
Correlation |
0.342 |
-0.085 |
-0.033 |
|
Significance |
0.064 |
0.656 |
0.863 |
|
Paired
samples test |
|
|
|
|
Mean difference |
0.039 |
-0.011 |
0.060 |
|
t |
3.042 |
-1.320 |
1.965 |
|
Degrees of freedom |
29 |
29 |
29 |
|
Significance (2-tailed) |
0.005 |
0.197 |
0.044 |
SD: Standard
deviation.
In terms of trefoil, the only
significant difference was in internal trefoil. There was no significant change
found in entire and corneal trefoil (Table 3).
Table 3 Trefoil
|
Parameters |
Entıre trefoil Preop./3rd
month |
Corneal trefoil Preop./3rd
month |
Internal trefoil Preop./3rd
month |
|
Paired
samples statistics |
|
|
|
|
Mean |
0.079/0.052 |
0.044/0.052 |
0.089/0.054 |
|
n |
30/30 |
30/30 |
30/30 |
|
SD |
0.071/0.029 |
0.028/0.056 |
0.064/0.035 |
|
Standart error mean |
0.013/0.005 |
0.005/0.010 |
0.012/0.006 |
|
Correlation |
-0.086 |
0.174 |
0.266 |
|
Significance |
0.650 |
0.356 |
0.156 |
|
Paired
samples test |
|
|
|
|
Mean difference |
0.027 |
-0.008 |
0.036 |
|
t |
1.877 |
-0.744 |
3.009 |
|
Degrees of freedom |
29 |
29 |
29 |
|
Significance (2-tailed) |
0.071 |
0.463 |
0.005 |
SD: Standard
deviation.
DISCUSSION
Our study demonstrated very good
outcomes of ICL implantation in the correction of moderate and high myopic and
astigmatic refractive disorder and supported other similar studies[12-18]. Up to -13.00 D spherical and
-4.75 D cylindrical errors were successfully corrected with the postoperative
mean residual spherical power of -0.73 D and the mean cylindrical error of
-0.89 D.
Besides the correction of the
refractive error, the quality of vision is a matter of patient satisfaction as
well. Our main purpose for this study was to evaluate the changes in HOAs after
implantation of ICL, which has unique impact on the visual image quality. There
are studies investigating changes induced by ICL implantation. Pérez-Vives et
al[19] pointed that the myopic ICLs had
negative spherical aberration. In their in vitro study, when the
refractive power increased, spherical aberration was more negative for myopic
ICLs and the values of other aberrations evaluated were minimal. Several in
vivo studies also showed an increase in spherical aberrations after ICL
implantation. In our study, we couldn’t find any statistically significant
difference between spherical aberration values. However, we found significant
change in internal trefoil. In a study designed by Kim et al[20] ICL implanted eyes were divided into two groups: eyes
with the small superior incision group (<
Igarashi et al[23] found that coma-like aberrations and tHOAs increased
significantly in eyes undergoing ICL implantation and they assumed that these
changes could be related to
Our study demonstrated changes in
tHOAs, coma and trefoil in entire and internal components. With these outcomes,
we can evaluate the optical effects of ICL implantation in detail. The
limitations of our study may be the subject number and the evaluation of the
HOAs in only one pupil diameter.
ACKNOWLEDGEMENTS
Presented in part at the Annual
Meeting of American Academy of Ophthalmology (AAO) 2016, Chicago and at the
XXXIV Congress of European Society of Cataract and Refractive Surgeons (ESCRS)
2016, Copenhagen.
Conflicts of Interest: Kayhan B, None; Coskunseven E, None; Sahin
O, None; Pallikaris I, None.
REFERENCES