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Comparison of intraocular lens decentration and tilt measurements using 2 Purkinje meter systems

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Purpose To evaluate the difference in intraocular lens tilt and decentration measurements with 2 Purkinje meters. Setting Vienna Institute for Research in Ocular Surgery, Hanusch Hospital, Vienna, Austria. Design Prospective evaluation of diagnostic test. Methods This single-center study included pseudophakic patients in 2 substudies in which 3 consecutive measurements were performed with 2 Purkinje meters (Spanish and German). In substudy 1, an inexperienced examiner performed all measurements after a short learning period. In substudy 2, all measurements were taken by experienced examiners under direct supervision of the inventors of the devices. Results Substudy 1 included 53 pseudophakic eyes in which all 53 scans were successful with the Spanish device; however, only 35 measurements (66%) were successful with the German Purkinje meter. The mean tilt measured with the Spanish Purkinje meter was 4.35 degrees ± 2.50 (SD) and 9.20 ± 6.96 degrees with the German Purkinje meter. The mean decentration was 0.44 ± 0.19 mm and 0.74 ± 0.91 mm, (P = .44), respectively. In substudy 2 (29 pseudophakic eyes), the number of successful scans was 29 (100%) and 18 (62%) for the Spanish meter and German Purkinje meter, respectively. The mean horizontal and vertical tilt difference vector between the 2 systems was 4.89 ± 3.24 degrees and 7.57 ± 3.82 degrees, respectively. Conclusions Concerning clinical feasibility, the Spanish Purkinje meter had a greater percentage of successful scans than the German device. In addition, this device measured significantly higher tilt values than the Spanish Purkinje meter.
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ARTICLE
Comparison of intraocular lens
decentration and tilt measurements using
2 Purkinje meter systems
Sophie Maedel, MD, Nino Hirnschall, MD, PhD, Natascha Bayer, MSc, Sabine Markovic, MD,
Juan Tabernero, PhD, Pablo Artal, PhD, Frank Schaeffel, PhD, Oliver Findl, MD, MBA
Purpose: To evaluate the difference in intraocular lens tilt and de-
centration measurements with 2 Purkinje meters.
Setting: Vienna Institute for Research in Ocular Surgery, Hanusch
Hospital, Vienna, Austria.
Design: Prospective evaluation of diagnostic test.
Methods: This single-center study included pseudophakic patients
in 2 substudies in which 3 consecutive measurements were p erformed
with 2 Purkinje meters (Spanish and German). In substudy 1, an
inexperienced examiner performed all measurements after a short
learning period. In substudy 2, all measurements were taken by
experienced examiners under direct supervision of the inventors of
the devices.
Results: Substudy 1 included 53 pseudophakic eyes in which
all 53 scans were successful with the Spanish device; however,
only 35 measurements (66%) were successful with the German
Purkinje meter. The mean tilt measured with the Spanish Pur-
kinje meter was 4.35 degrees G2.50 (SD) and 9.20 G6.96
degrees with the German Purkinje meter. The mean decentra-
tion was 0.44 G0.19 mm and 0.74 G0.91 mm, (PZ.44),
respectively. In substudy 2 (29 pseudophakic eyes), the number
of successful scans was 29 (100%) and 18 (62%) for the
Spanish meter and German Purkinje meter, respectively. The
mean horizontal and vertical tilt difference vector between the
2 systems was 4.89 G3.24 degrees and 7.57 G3.82 degrees,
respectively.
Conclusions: Concerning clinical feasibility, the Spanish Purkinje
meter had a greater percentage of successful scans than the
German device. In addition, this device measured significantly high-
er tilt values than the Spanish Purkinje meter.
J Cataract Refract Surg 2017; 43:648655 Q2017 ASCRS and ESCRS
The increasing number of implantations of aspheric,
toric, and multifocal intraocular lenses (IOLs) dur-
ing cataract surgery has improved postoperative vi-
sual quality of cataract patients.
1,2
However, exact
alignment of these premium IOLs is mandatory because
decentration, tilt, or rotation (in the case of toric IOLs)
could result in reduced visual quality. Holladay et al.
3
showed in an eye model that decentration more than
0.4 mm or tilt more than 7 degrees result in a loss of the
beneficial effect of an aspheric IOL compared with a
spherical IOL. Piers et al.
4
found these critical values to
be more tolerable with 0.8 mm of decentration and
10 degrees of tilt.
Several techniques have been used to measure IOL
decentration and tilt, such as slitlamp examination, retroil-
lumination photography,
5
rotating Scheimpflug imaging,
68
optical coherence tomography,
911
and the analysis of Pur-
kinje reflexes.
1217
Slitlamp examination is a subjective
method that allows approximate decentration measure-
ments but no quantitative tilt measurements. For this mea-
surement, the pupil has to be dilated.
For Scheimpflug imaging, the pupil must be sufficiently
dilated to make the optic edge and the posterior surface
of the IOL visible.
The concept of Purkinje reflexes analysis dates back to
the 19th century, when candles were used to generate
Submitted: June 27, 2016 |Final revision submitted: December 22, 2016 |Accepted: January 22, 2017
From the Vienna Institute for Research in Ocular Surgery (Maedel, Hirnschall, Markovic, Findl), A Karl Landsteiner Institute, Hanusch Hospital, and Laser and Optics in
Applied Life Sciences (Bayer), University of Applied Sciences Technikum Wien, Vienna, Austria; Laboratorio de
Optica (Tabernero, Artal), Departamento de F
õsica,
Universidad de Murcia, Murcia, Spain; Vision & Eye Research Unit (Tabernero), Postgraduate Medical Institute, Anglia Ruskin University, Cambridge, and Moorfields Eye
Hospital NHS Foundation Trust (Findl), London, United Kingdom; the Section of Neurobiology of the Eye (Schaeffel), Institute for Ophthalmic Research, T
ubingen,
Germany.
Presented in part at the XXIX Congress of the European Society of Cataract and Refractive Surgeons, Vienna, Austria, September 2011.
Corresponding author: Oliver Findl, MD, MBA, Hanusch Hospital, Department of Ophthalmology, Heinrich-Collin-Straße 30, 1140 Vienna, Austria. E-mail:
oliver@findl.at.
Q2017 ASCRS and ESCRS
Published by Elsevier Inc.
0886-3350/$ - see frontmatter
http://dx.doi.org/10.1016/j.jcrs.2017.01.022
648
reflections of ocular optic surfaces.
18
In the 1990s, light-
emitting diodes (LEDs) were used to analyze the alignment
of Purkinje reflexes III and IV.
19,20
The analysis of Purkinje
reflexes has been shown to be more accurate than using
Scheimpflug images.
21
A Purkinje meter developed by
Tabernero et al.
22
(called the Spanish Purkinje meter in
this study) at the University of Murcia, Spain, was shown
to be highly reproducible in assessing IOL tilt and
decentration
14
and detecting differences in capsular bag
performance of different IOL designs.
23
Another Purkinje
meter device developed by Schaeffel
24
(called the German
Purkinje meter in this study) has a setup similar to the
construction of Tabernero et al.
22
As a potential
advancement over the Spanish meter, this device is portable
and includes a gaze tracker. It has been shown to measure
crystalline lens tilt and decentration in healthy eyes even
without pupil dilation.
25
Recently, it has been shown to
have high reliability and reproducibility in pseudophakic
eyes.
26,27
The aim of this study was to evaluate the difference in
IOL tilt and decentration measurements with 2 clinical
Purkinje meter systems.
PATIENTS AND METHODS
This prospective single-center study included pseudophakic pa-
tients who had uneventful standard small-incision cataract sur-
gery 3 to 12 months before recruitment and had otherwise
healthy eyes. Exclusion criteria were complications during cataract
surgery, severe opacities of the cornea or the IOL, posterior capsule
opacification, or any pathologies preventing the patient from ac-
curate fixation, such as significant macula pathologies or ambly-
opia. All the research and measurements followed the tenets of
the Declaration of Helsinki.
This study consisted of 2 subgroups, for which only 1 visit was
necessary. During this visit, pupils were dilated before examina-
tions with tropicamide 1.0% (Mydriaticum) and phenylephrine
10.0% (NeosynephrinPOS 10.0%). In both substudies, 3 consec-
utive measurements were performed with the 2 Purkinje meters
(1 from Spain [Figure 1] and 1 from Germany [Figure 2]). The de-
vice to be used for measurements first was chosen randomly in
both substudies. Randomization was performed using an online
random generator.
A
In substudy 1, an inexperienced examiner performed all mea-
surements after a short learning period of 20 measurements
with both Purkinje meters. Measurements were performed on a
continuous cohort.
Figure 1. Left: Setup of the Spanish Purkinje meter. Right: Pupillary
margin (red) and Purkinje reflexes I, III, and IV after manual marking
with the meters software (P ZPurkinje reflex).
Figure 3. Pseudophakic eye modelled according to the Liou and
Brennan eye model
28
(IOL Zintraocular lens).
Figure 2. Top: Setup of German Purkinje meter. Bottom: Appear-
ance of the 3 Purkinje images in the pupil (LED Zlight-emitting
diode; P ZPurkinje reflex).
649IOL DECENTRATION AND TILT MEASUREMENTS WITH 2 PURKINJE METER SYSTEMS
Volume 43 Issue 5 May 2017
In substudy 2, pseudophakic patients were invited to participate
in the study in which tilt and decentration measurements would be
taken with both devices. All measurements were taken by experi-
enced examiners under the supervision of the inventors of the de-
vices (J.T. and F.S.). Between the consecutive 3 measurements, the
patient was asked to sit back, after which the chinrest and the po-
sition of the Purkinje meter were changed slightly to allow system
realignment. All measurements of substudy 2 were performed on
the same day.
Spanish Purkinje Meter
The technical details of the Spanish Purkinje meter system have
been described.
22,23
In short, a semicircular array of LEDs was
projected on the patients eye as the patient fixated on a light.
The 3 reflexes (Purkinje I, III, and IV), reflected by the optical
surface of the eye, were captured with the digital camera of
the device. Then, the semicircles were marked manually by the
operator. Afterward, the IOL tilt in relation to the pupillary
axis (tilt
pup
) and to the line of sight (tilt
LOS
) as well as decentra-
tion were calculated automatically by the dedicated software ac-
cording to misalignment of the Purkinje images. Figure 1 shows
an image of the Purkinje reflections and the manual marking
method.
German Purkinje Meter
The setting of this device has been described.
24
The patients head
was placed on a chinrest, and the device was positioned in front of
him or her. Because this system is movable, focus is coded as sound
with variable frequency to allow positioning the camera in the op-
timum focus to obtain a sharp image of the eye. The patient was
asked to fixate on an LED target, and images of the Purkinje re-
flexes were captured. Subsequently, the observer manually marked
the pupil margin and the reflexes. To stimulate changes in gaze po-
sition in consecutive measurements, the patient was asked to fixate
on numbers printed on a plastic ring that was attached to the cam-
era lens. Three images were captured. Then, the program per-
formed regression analysis for the distance of Purkinje III and
Purkinje IV in the x-direction and the y-direction versus the
angular direction of the fixation axis in the x-direction and y-di-
rection. The regression lines were then displayed automatically.
In cases in which the significance of regression was too low
(regression coefficient R!0.95), an error message was displayed
and image capture was repeated.
Statistical Analysis
For statistical analysis, Excel for Mac software (2011, Microsoft
Corp.) and SPSS for Mac software (version 23.0, International
Business Machines Corp.) were used. Tilt and decentration values
are listed as vectors, if not stated otherwise. Descriptive data are
shown as 95% confidence interval, means GSD, and range. After
the distribution of data was shown to be not normally distributed,
a nonparametric test (Wilcoxon signed-rank test) was used for sig-
nificance testing, if not stated otherwise.
Computational Model
To show the effect of tilt and decentration of an aspheric IOL on
optical lower-order aberrations (LOAs) and higher-order aberra-
tions (HOAs), a ray-tracing simulation (Optic Studio 5, Zemax
LLC) was calculated within an eye model. The tilt and decentra-
tion sensitivity of the MC6125AS aspheric IOL (Humanoptics
AG) was tested using specifications of the Liou and Brennan sche-
matic eye.
28
Within the model, a pupil decentration of 0.5 mm and
a tilted visual axis of 5 degrees were simulated. Figure 3 shows the
modeled pseudophakic eye. The natural lens was replaced with an
aspheric IOL to simulate the influence of the IOLs position on the
Zernike coefficients up to the 4th order.
During modeling, the IOL was positioned so that the ante-
rior principal plane of the artificial implant coincided with
the anterior principal plane of the natural lens. The study
used a 3.0 mm pupil diameter. The wavelength used for simu-
lation was 546 nm.
Figure 4 shows the displacements that were evaluated. The IOL
tilt around the y-axis and around the x-axis was tested. Decentra-
tion of the IOL was determined along the Cx-axis (nasally) and
the Cy-axis (superiorly).
Figure 4. Cross-sectionand coordinatesystem of a pseudophakic hu-
man eye and the total wavefront map obtained by an aberrometer.
Figure 5. Differences between tilt measurements with both systems
in substudy 1 and substudy 2. Positive values indicate that tilt
measured with the Spanish meter is higher than with the German
meter. Asterisks represent extreme outliers.
650 IOL DECENTRATION AND TILT MEASUREMENTS WITH 2 PURKINJE METER SYSTEMS
Volume 43 Issue 5 May 2017
RESULTS
Substudy 1 comprised 53 pseudophakic eyes of 53 patients.
All measured eyes had a 1-piece acrylic IOL with open-loop
haptics implanted (Tecnis ZCB00, Abbott Medical Optics,
Inc.; Superflex 620H, Rayner Intraocular Lenses Ltd.; or
Idea Xcelens, Croma Pharma). After excluding the unsuc-
cessful scans, the measurements of 35 eyes were included
for further analysis.
The mean tilt
LOS
measure was 4.35 G2.50 degrees (range
1.15 to 11.36 degrees) with the Spanish meter and
9.20 G6.96 degrees (range 2.23 to 37.80 degrees) with
the German meter. Both tilt
pup
and tilt
LOS
vectors were
lower with the Spanish meter than with the German meter
(P!.01). Figure 5 shows the differences between tilt vec-
tors of the devices. Decentration values were similar for
both devices with mean 0.44 G0.19 mm (range 0.08 to
0.85 mm) and 0.74 G0.91 mm (range 0.07 to 4.31 mm),
respectively (PZ.44) (Figure 6).
In substudy 2, 32 patients were invited to have measure-
ments; however, 3 did not answer the letter of invitation,
thus 29 patients attended on the day of measurements.
Concerning clinical feasibility, the measurements in all
29 eyes of 29 patients (100%) were successful with the
Spanish meter, whereas only 18 measurements (62%)
with the German meter could be used for analysis.
The mean horizontal and vertical tilt difference vector be-
tween the 2 systems was 4.89 G3.24 degrees (Spanish me-
ter) and 7.57 G3.82 degrees (German meter). The
mean difference vectors for horizontal and vertical
decentration measurements were 0.30 G0.28 mm
and 0.35 G0.15 mm, respectively (Figures 7 and 8).
Concerning the direction of horizontal and vertical IOL
tilt, the measurements with the 2 systems were in agreement
Figure 7. Vectors between tilt measurements (top) and decentration
measurements (bottom) for both devices in substudy 2. Asterisk
represents extreme outlier.
Figure 6. Differences between decentration measurements with
both systems for substudy 1 and substudy 2. Positive values indi-
cate that the decentration measured with the Spanish meter was
higher than with the German meter. Circles represent outliers, and
asterisks represent extreme outliers.
651IOL DECENTRATION AND TILT MEASUREMENTS WITH 2 PURKINJE METER SYSTEMS
Volume 43 Issue 5 May 2017
in 14 cases (78%) and 17 cases (94%), respectively. For hor-
izontal and vertical IOL decentration, direction of the mea-
surements was congruent in 10 cases (56%) and 13 cases
(72%), respectively.
Computational Model
Table 1 shows the results of the simulation using the model
eye. Figure 9 shows the simulated LOAs and HOAs.
DISCUSSION
The aim of this study was to assess the feasibility and short-
term reproducibility of 2 Purkinje meters. Concerning
feasibility, the Spanish meter performed significantly better
than the German meter. For the German meter, only 66% of
measurements were successful in substudy 1. To ascertain
that the number of unsuccessful measurements was not
caused by improper use of the Purkinje meter systems,
Figure 8. Bland-Altman plots for
horizontal tilt, vertical tilt, horizon-
tal decentration, and vertical de-
centration in substudy 2.
Table 1. The results of ocular wavefront simulation using the model eye by Liou and Brennan.
28
Image*y-Tilt ()x-Tilt ()x-Shift (mm) y-Shift (mm)
Simulated Aberrations (mm)
Z(1,1) Z(L1,1) Z(0,2) Z(2,2)
a1.15 ddd0.208 0.000 0.005 0.112
b2.23 ddd0.254 0.000 0.047 0.153
c4.35 ddd0.348 0.000 0.167 0.250
d9.2 ddd0.581 0.000 0.543 0.561
e11.36 ddd0.696 0.000 0.762 0.746
f37.8 ddd3.827 0.000 8.554 8.325
g4.89 ddd0.373 0.000 0.202 0.279
hd7.57 dd0.161 0.321 0.089 0.045
i4.89 7.57 dd0.381 0.331 0.351 0.160
jdd0.07 d0.150 0.000 0.053 0.079
kdd0.08 d0.148 0.000 0.053 0.079
ldd0.44 d0.118 0.000 0.067 0.099
mdd0.74 d0.120 0.000 0.091 0.110
ndd0.85 d0.127 0.000 0.100 0.115
odd4.31 ddddd
pdd0.30 d0.126 0.000 0.059 0.093
qddd0.35 0.162 0.056 0.069 0.084
rdd0.30 0.35 0.131 0.049 0.073 0.104
ZZZernike
*Letters correspond to letters of images in Figure 9
652 IOL DECENTRATION AND TILT MEASUREMENTS WITH 2 PURKINJE METER SYSTEMS
Volume 43 Issue 5 May 2017
the inventers of both systems attended all measurements in
substudy 2. The inventors of both systems were asked to
observe the examiners and guide them, if necessary. In a
few cases, they also repeated the measurements themselves
if the examiners did not obtain a successful measurement.
However, despite this change in measurement setup in sub-
study 2, 38% of eyes were still not measurable with the
German meter, whereas all eyes could be measured in
both substudies with the Spanish meter.
Using Purkinje reflexes for the analysis of IOL alignment
has advantages. It is a noncontact technique, not dependent
on pupil dilation, clinically feasible, and achieves fast results.
Nishi et al.
14
showed that the Spanish meter is a reliable
instrument to measure IOL tilt and decentration even in
extreme cases. Intraexaminer and interexaminer reproduc-
ibility of IOL decentration and tilt measurements was high
with the Spanish meter. Even in cases with insufficient pupil
dilation or clinically manifest IOL decentration and tilt, the
reproducibility of measurements was good.
As mentioned earlier, the German meter has been shown
to measure tilt of the crystalline lens in healthy eyes
24,25
and
pseudophakic eyes,
26,27
and measurements were shown to
be reproducible over time. In a clinical study by Mester
et al.,
27
IOL tilt and decentration measured with the
German meter were lower than the same values measured
with the German meter in our study and similar to the
values measured with the Spanish meter; however, Mester
et al. did not mention problems with the clinical feasibility
of the German meter.
We compared the systems and found differences con-
cerning using them in a clinical setting. The Spanish meter
has a fixed chinrest and an LED fixation target to allow
for repeatable measurements. The system is aligned in all
3 planes with a joystick, equivalent to most models used
for many ophthalmic imaging devices. A possible advantage
of the German meter is that the device consists of a compact
video camera and a laptop computer; this makes the system
portable. It might be why, in our hands, the German meter
system was more challenging to align because the recording
camera was mounted on a rotatable stick, which could be
varied in multiple directions. In addition, this system uses
only a single LED, whereas the Spanish meter uses a semi-
circular array of LEDs. The single-spot Purkinje reflexes
induced by the German meter make estimation of the opti-
mum focusing of the camera difficult. Another problem is
that the single-spot reflexes are small and symmetrical,
which in some cases made identification of the Purkinje re-
flexes I, III, and IV almost impossible, in particular when
the reflexes were superimposed on each other. This might
be an explanation for some of the unsuccessful measure-
ments with the German meter. However, one third of the
measurements with this device could not be used for anal-
ysis, even when the measurements were performed by the
inventor (F.S.).
To our knowledge, there are no actual data concerning the
comparability of the 2 Purkinje meters used in this study.
However, the clinical feasibility results were similar in the
2 substudies. Despite the presence of the inventor of the
Purkinje German meter during the measurements in
substudy 2, the number of successful scans did not increase.
Both inventors were asked to analyze the data obtained
with their respective device during our measurements,
which could be a source of error. Although the inventor
of the German meter did analyze the image data, the num-
ber of successful scans did not increase, which might indi-
cate that the influence of the experience of the examiner
during image acquisition and evaluation might not be as
relevant as one might think.
Table 1. (Cont.)
Simulated Aberrations (mm)
Z(L2,2) Z(1,3) Z(L1,3) Z(3,3) Z(L3,3) Z(0,4) Z(2,4) Z(L2,4) Z(4,4) Z(L4,4)
0.000 0.076 0.000 0.000 0.000 0.040 0.001 0.000 0.000 0.000
0.000 0.093 0.000 0.001 0.000 0.041 0.001 0.000 0.000 0.000
0.000 0.126 0.000 0.002 0.000 0.041 0.002 0.000 0.000 0.000
0.000 0.210 0.000 0.008 0.000 0.043 0.003 0.000 0.000 0.000
0.000 0.252 0.000 0.012 0.000 0.044 0.004 0.000 0.000 0.000
0.000 1.419 0.000 0.493 0.000 0.128 0.098 0.000 0.041 0.000
0.000 0.135 0.000 0.002 0.000 0.041 0.002 0.000 0.000 0.000
0.236 0.059 0.115 0.002 0.000 0.041 0.000 0.001 0.000 0.000
0.400 0.138 0.119 0.003 0.004 0.042 0.001 0.002 0.000 0.000
0.000 0.056 0.000 0.001 0.000 0.041 0.001 0.000 0.000 0.000
0.000 0.055 0.000 0.001 0.000 0.041 0.001 0.000 0.000 0.000
0.000 0.046 0.000 0.004 0.000 0.046 0.004 0.000 0.000 0.000
0.000 0.048 0.000 0.010 0.000 0.051 0.008 0.000 0.000 0.000
0.000 0.051 0.000 0.013 0.000 0.053 0.009 0.000 0.000 0.000
dddddddddd
0.000 0.049 0.000 0.003 0.000 0.044 0.003 0.000 0.000 0.000
0.029 0.060 0.018 0.001 0.001 0.041 0.000 0.002 0.000 0.000
0.014 0.050 0.015 0.001 0.004 0.045 0.002 0.003 0.000 0.000
653IOL DECENTRATION AND TILT MEASUREMENTS WITH 2 PURKINJE METER SYSTEMS
Volume 43 Issue 5 May 2017
Concerning IOL tilt measurements, the German meter
measured significantly higher tilt values than the Spanish
meter. The congruence between the devices concerning the
direction of IOL tilt was better for the vertical measurements
than for the horizontal measurements. The IOL decentration
values tended to be higher with the German meter, although
the differences were not statistically significant. Despite these
results in our pseudophakic patients, the German meter has
been shown to measure lens tilt and decentration reliably
and with good repeatabilty.
24,25
Repeatability with the Span-
ish meter had a relatively low influence on HOAs. In
contrast, repeatability of the German meter would have re-
sulted in significant HOAs, resulting in reduced visual qual-
ity. However, because 7 degrees of tilt and 0.4 mm of
decentration can have a significant influence,
3
we would
consider a repeatability of 1.4 degrees and 0.08 mm (20%
of the relevant influence) to be acceptable.
In conclusion, the Spanish meter had better clinical feasi-
bility in pseudophakic eyes than the German meter. Despite
the supervision of a highly experienced specialist during
measurements, the percentage of unsuccessful scans with
the German meter was relatively high. In addition, the
German device measured significantly higher tilt values
than the Spanish meter. Data published with these Purkinje
meters should not be directly compared because of the dif-
ferences found in this study.
WHAT WAS KNOWN
Several techniques to assess IOL tilt and decentration lack
accuracy and objectivity.
Using the Purkinje reflexes to measure IOL alignment yields
repeatable and reproducible results.
WHAT THIS PAPER ADDS
The clinical feasibility of the Spanish Purkinje meter system
was better than that of the German Purkinje meter.
In pseudophakic eyes, the German Purkinje meter
measured significantly higher IOL tilt and decentration values
than the Spanish Purkinje meter.
REFERENCES
1. Schuster AK, Tesarz J, Vossmerbaeumer U. Ocular wavefront analysis of
aspheric compared with spherical monofocal intraocular lenses in cataract
surgery: systematic review with metaanalysis. J Cataract Refract Surg
2015; 41:10881097
Figure 9. Ocular wavefronts simulated in the model eye. Table 1 shows the corresponding values.
654 IOL DECENTRATION AND TILT MEASUREMENTS WITH 2 PURKINJE METER SYSTEMS
Volume 43 Issue 5 May 2017
2. Visser N, Beckers HJM, Bauer NJC, Gast STJM, Zijlmans BLM,
Berenschot TTJM, Webers CA, N uijts RMMA. Toric vs aspherical control intraoc-
ular lenses in patients with cataract and corneal astigmatism; a randomized clin-
ical trial. JAMA Ophthalmol 2014; 132:14621468. Available at: http://
jamanetwork.com/journals/jamaophthalmology/fullarticle/1906175.Ac-
cessed March 12, 2017
3. Holladay JT, Piers PA, Koranyi G, van der Mooren M, Norrby NES. A new
intraocular lens design to reduce spherical aberration of pseudophakic
eyes. J Refract Surg 2002; 18:683691
4. Piers PA, Weeber HA, Artal P, Norrby S. Theoretical comparison of
aberration-correcting customized and aspheric intraocular lenses.
J Refract Surg 2007; 23:374384
5. Findl O, Buehl W, Menapace R, Georgopoulos M, Rainer G, Siegl H,
Kaider A, Pinz A. Comparison of 4 methods for quantifying posterior
capsule opacification. J Cataract Refract Surg 2003; 29:106111
6. Baumeister M, B
uhren J, Kohnen T. Tilt and decentration of spherical and
aspheric intraocular lenses: effect on higher-order aberrations. J Cataract
Refract Surg 2009; 35:10061012
7. Rosales P, De Castro A, Jim
enez-Alfaro I, Marcos S. Intraocular lens align-
ment from Purkinje and Scheimpflug imaging. Clin Exp Optom 2010;
93:400408. Available at: http://onlinelibrary.wiley.com/doi/10.1111/j.
1444-0938.2010.00514.x/epdf. Accessed March 12, 2017
8. Kr
anitz K, Mih
altz K, S
andor GL, Takacs A, Knorz MC, Nagy ZZ. Intraocular
lens tilt and decentration measured by Scheimpflug camera following
manual or femtosecond laser-created continuous circular capsulotomy.
J Refract Surg 2012; 28:259263
9. Kumar DA, Agarwal A, Prakash G, Jacob S, Saravanan Y, Agarwal A.
Evaluation of intraocular lens tilt with anterior segment optical coher-
ence tomography. Am J Ophthalmol 2011; 151:406412. Available at:
http://www.ajo.com/article/S0002-9394(10)00724-5/pdf. Accessed
March 12, 2017
10. Marcos S, Ortiz S, P
erez-Merino P, Birkenfeld J, Dur
an S, Jim
enez-
Alfaro I. Three-dimensional evaluation of accommodating intraocular
lens shift and alignment in vivo. Ophthalmology 2014; 121:4555. Avail-
able at: http://www.aaojournal.org/article/S0161-6420(13)00529-0/pdf.
Accessed March 12, 2017
11. Wang X, Dong J, Wang X, Wu Q. IOL tilt and decentration estimation from 3
dimensional reconstruction of image. PLoS One 2013; 8:e59109. Available
at: http://journals.plos.org/plosone/article/file?idZ10.1371/journal.pone.
0059109&typeZprintable. Accessed March 12, 2017
12. Mester U, Sauer T, Kaymak H. Decentration and tilt of a single-piece
aspheric intraocular lens compared with the lens position in young phakic
eyes. J Cataract Refract Surg 2009; 35:485490
13. Mutlu FM, Erdurman C, Sobaci G, Bayraktar MZ. Comparison of tilt and de-
centration of 1-piece and 3-piece hydrophobic acrylic intraocular lenses.
J Cataract Refract Surg 2005; 31:343347
14. Nishi Y, Hirnschall N, Crnej A, Gangwani V, Tabernero J, Artal P, Findl O.
Reproducibility of intraocular lens decentration and tilt measurement using
a clinical Purkinje meter. J Cataract Refract Surg 2010; 36:15291535.
Available at: http://lo.um.es/panel/secciones/noticias/adjuntos/14.pdf.
Accessed March 12, 2017
15. Phillips P, P
erez-Emmanuelli J, Rosskothen HD, Koester CJ. Measurement
of intraocular lens decentration and tilt in vivo. J Cataract Refract Surg 1988;
14:129135
16. Auran JD, Koester CJ, Donn A. In vivo measurement of posterior
chamber intraocular lens decentration and tilt. Arch Ophthalmol 1990;
108:7579
17. Kirschkamp T, Dunne M, Barry J-C. Phakometric measurement of
ocular surface radii of curvature, axial separations and alignment in
relaxed and accommodated human eyes. Ophthalmic Physiol Opt
2004; 24:6573
18. Belin MW, Khachikian SS. An introduction to understanding elevation-
based topography: how elevation data are displayed a review. Clin Exp
Ophthalmol 2009; 37:1429. Available at: http://onlinelibrary.wiley.com/
doi/10.1111/j.1442-9071.2008.01821.x/pdf. Accessed March 12, 2017
19. Guyton DL, Uozato H, Wisnicki HJ. Rapid determination of intraocular lens
tilt and decentration through the undilated pupil. Ophthalmology 1990;
97:12591264
20. Korynta J, Cendelin J, Bok J. [Relation between postoperative refraction er-
rors and decentration of the intraocular lens]. [Czechoslovakian] Cesk Oftal-
mol 1994; 50:219225
21. de Castro A, Rosales P, Marcos S. Tilt and decentration of intraocular
lenses in vivo from Purkinje and Scheimpflug imaging; validation study.
J Cataract Refract Surg 2007; 33:418429
22. Tabernero J, Benito A, Nourrit V, Artal P. Instrument for measuring the
misalignments of ocular surfaces. Instrument for measuring the
misalignments of ocular surfaces. Opt Express 2006; 14:1094510956.
Available at: https://www.osapublishing.org/oe/viewmedia.cfm?uriZoe-
14-22-10945&seqZ0. Accessed March 12, 2017
23. Crnej A, Hirnschall N, Nishi Y, Gangwani V, Tabernero J, Artal P, Findl O.
Impact of intraocular lens haptic design and orientation on decentration
and tilt. J Cataract Refract Surg 2011; 37:17681774
24. Schaeffel F. Binocular lens tilt and decentration measurements in
healthy subjects with phakic eyes. Invest Ophthalmol Vis Sci 2008;
49:22162222. Available at: http://iovs.arvojournals.org/article.aspx?
articleidZ2125511. Accessed March 12, 2017
25. Chen Y, Schaeffel F. Crystalline lens thickness determines the perceived
chromatic difference in magnification. J Opt Soc Am A Opt Image Sci Vis
2014; 31:524531
26. Janunts E, Chashchina E, Seitz B, Schaeffel F, Langenbucher A. Reliability
of a single light source Purkinjemeter in pseudophakic eyes. Optom Vis Sci
2015; 92:884891. Available at: http://journals.lww.com/optvissci/Fulltext/
2015/08000/Reliability_of_a_Single_Light_Source_Purkinjemeter.8.aspx.
Accessed March 12, 2017
27. Mester U, Heinen S, Kaymak H. Klinische Ergebnisse unter besonderer
Ber
ucksichtigung von Dezentrierung und Verkippung der asph
arischen In-
traokularlinse FY-60AD [Clinical results of the aspheric intraocular lens
FY-60AD (Hoya) with particular respect to decentration and tilt]. Ophthal-
mologe 2010; 107:831836
28. Liou H-L, Brennan NA. Anatomically accurate, finite model eye for optical
modeling. J Opt Soc Am A 1997; 14:16841695
OTHER CITED MATERIAL
A. Random.org. True random number service. Available at: http://www.
random.org. Accessed March 12, 2017
Disclosures: Drs. Tabernero and Artal are patent assignees for the
Spanish Purkinje meter system. Dr. Schaeffel is patent assignee for the
German Purkinje meter. None of the other authors has a financial or
proprietary interest in any material or method mentioned.
First author:
Sophie Maedel, MD
Vienna Institute for Research in Ocular
Surgery, A Karl Landsteiner Institute,
Hanusch Hospital, Vienna, Austria
655IOL DECENTRATION AND TILT MEASUREMENTS WITH 2 PURKINJE METER SYSTEMS
Volume 43 Issue 5 May 2017
... These include slit lamp assessment, 21 retroillumination photography, 22 Scheimpflug imaging, 16 optical coherence tomography, [23][24][25] and measurements using Purkinje reflections. [26][27][28] But before the implant injection into the eye, a study on reliable prediction of the visual outcome of the implantation needs to be performed. Up to now, many efforts have been made to predict the postoperative visual quality of the pseudophakic eyes. ...
... Most studies focus either on the optimization of the optical geometry of the IOL [29][30][31][32] or the influence of the postoperative lens position on the optical performance. 28,33,34 To reliably predict the postoperative optical performance and the mechanical behavior of the intraocular implant, it is required for IOL to have strict quality and performance features, which may be useful for this prediction. This stage is of major importance if the implantation is aimed to be a safer and even more effective method of cataract treatment. ...
... The model was based on the emmetropic Atchison schematic eye (see Table 1 for details), 36 where the gradient index crystalline lens was replaced with a particular IOL to estimate the image quality deterioration being the result of the IOL displacement. Following the procedures presented in earlier studies, 28 for the purposes of optical performance simulations, the initial position of the IOL within the pseudophakic eye model was optimized so that its anterior principal plane coincided with the anterior principal plane of the crystalline lens of the original, phakic model. The magnitude of the IOL displacement (at the point of final configuration, where the distance between the clamps is equal to zero), namely tilt around the xand y-axes, decentration along the xand y-axes were adapted according to the characteristics resulted directly from the FEM modeling, presented in Sec. 4. The axial displacement was not taken into account in the optical performance simulations intentionally since it only produces a defocus (about 1.5 D for 2 mm of axial displacement), which masks the effects induced by decentering and tilt of the IOL. ...
Article
Full-text available
Intraocular lenses (IOLs) are used in the cataract treatment for surgical replacement of the opacified crystalline lens. Before being implanted they have to pass the strict quality control to guarantee a good biomechanical stability inside the capsular bag, avoiding the rotation, and to provide a good optical quality. The goal of this study was to investigate the influence of the material and haptic design on the behavior of the IOLs under dynamic compression condition. For this purpose, the strain-stress characteristics of the hydrophobic and hydrophilic materials were estimated experimentally. Next, these data were used as the input for a finite-element model (FEM) to analyze the stability of different IOL haptic designs, according to the procedure described by the ISO standards. Finally, the simulations of the effect of IOL tilt and decentration on the optical performance were performed in an eye model using a ray-tracing software. The results suggest the major importance of the haptic design rather than the material on the postoperative behavior of an IOL. FEM appears to be a powerful tool for numerical studies of the biomechanical properties of IOLs and it allows one to help in the design phase to the manufacturers.
... D [42]. The tilt of the lens or IOL can be measured by different methods, including those based on the Purkinje reflexes [44,45], the Scheimpflug systems, and OCT [46,47], with small differences between them [45]. ...
... D [42]. The tilt of the lens or IOL can be measured by different methods, including those based on the Purkinje reflexes [44,45], the Scheimpflug systems, and OCT [46,47], with small differences between them [45]. ...
Article
Purpose Intraocular lens (IOL) calculation and biometry have evolved significantly in recent decades. However, present outcomes are still suboptimal. Our objective is to summarize the results reported in the literature with regard to a new variable, the value of the relationship between anterior and posterior corneal curvature in the biometric calculation of IOL power. Methods We have created a narrative revision of the existing evidence regarding the posterior to anterior corneal curvature ratio in IOL calculation. Results The corneal posterior/anterior ratio (P/A ratio), also called Gullstrand ratio, has a standard deviation of 2.4% in normal people, hence causing a possible IOL power miscalculation error of up to 0.75 diopters (D). This error is magnified in pathological corneas or in those with previous refractive surgery. Including the P/A ratio in the IOL formula reduces errors in the calculation of IOL power. Conclusions Measurement of the posterior corneal surface should be recommended prior to IOL calculation, given the demonstrated results regarding the P/A ratio for IOL power calculation. Regarding toric IOL calculation, we suggest incorporation of all internal astigmatic vectors, for instance, posterior corneal surface, IOL tilt induced toricity, and retinal astigmatism. All of these factors may improve surgical outcomes.
... [10][11][12][13] Follow-up investigations were performed at 1 h, 1 month, 1 year and 2 years after surgery. The examinations included: subjective-and auto-refraction, corrected and uncorrected distance visual acuity, evaluation of tilt and decentration of the lens using a Purkinje meter, 8,14 subjective evaluation of glistenings and PCO grading using AQUA software (Automated Quantification of After-Cataract). 5,13,15 Statistical analysis . ...
... 19 There are several methods of measuring IOL misalignment, but studies have shown that the Purkinje meter is a precise method, with a good reproducibility and high correlation with slit lamp examination. 8,14 This study determined similar AQUA PCO scores for the control IOL, with a slightly higher score for the study IOL. Nevertheless, the difference was not statistically significant, thus a clear difference in PCO development between the two lenses cannot be demonstrated. ...
Article
Purpose: To determine the visual outcome, intraocular lens (IOL) stability and posterior capsule opacification (PCO) rate of a hydrophobic acrylic intraocular lens. Setting: Vienna Institute for Research in Ocular Surgery, Hanusch Hospital, Vienna, Austria. Design: This double-masked randomised study included patients who underwent standard cataract surgery. Method: Patients received either the hydrophobic acrylic IOL (iPure, PhysIOL) or the hydrophobic acrylic control IOL (Tecnis ZCB00, Johnson&Johnson). Subjective refraction, uncorrected and corrected distance visual acuity (UDVA, CDVA), IOL tilt and decentration (Purkinje meter) and PCO intensity using retroillumination images with automated image analysis (automated quantification of after-cataract, AQUA), were evaluated for both groups 2 years after surgery. Results: A total number of 31 patients completed the 2-year follow-up, 16 in the study group and 15 in the control group. The CDVA was 0.0 logMAR (standard deviation - SD: 0.1) for the study IOL and 0.1 logMAR (SD: 0.2) for the control IOL, p = 0.001. The AQUA PCO score for the study group was 2.1 and 1.4 for the control group, p = 0.44. Mean IOL tilt was 2.9° (SD: 1.8) in the study group and 5.0° (SD: 4.5) in the control group, whilst the mean decentration was 0.37 mm (SD: 0.18) and 0.45 mm (SD: 0.3), p = 0.610. Conclusion: The studied parameters revealed a good performance for both IOLs. Both IOLs had good CDVA, a small amount of tilt and decentration and none of the patients required laser capsulotomies during the follow-up time of 2 years after surgery.Presented at the 37th ESCRS Congress Paris, France, September 2019.
... Several methods have been used to measure IOL tilt and decentration, such as the Scheimpflug method, 5,14,19 the Purkinje method, 20,21 or anterior segment optical coherence tomography (OCT). 15 These methods utilize different reference axes, the pupillary or visual axis, to assess the IOL position. ...
Article
Full-text available
Purpose: The purpose of this study was to investigate the characteristics and risk factors of intraocular lens (IOL) tilt and decentration of phacoemulsification after pars plana vitrectomy (PPV) using swept-source optical coherence tomography (SS-OCT). Methods: One hundred four eyes with prior PPV and 104 eyes without PPV undergoing uneventful cataract surgery were enrolled in this study. IOL tilt and decentration were measured by SS-OCT (CASIA2) 3 months postoperatively. Results: The mean IOL tilt and decentration were greater in the PPV group (5.36 ± 2.50 degrees and 0.27 ± 0.17 mm, respectively) than in the non-PPV group (4.54 ± 1.46 degrees, P = 0.005; 0.19 ± 0.12 mm, P < 0.001, respectively). Multiple logistic regression showed that silicone oil (SO) tamponade (odds ratio [OR] = 5.659, P = 0.021) and hydrophilic IOL (OR = 5.309, P = 0.022) were associated with IOL tilt over 7 degrees, and diabetes mellitus (DM; OR = 5.544, P = 0.033) was associated with IOL decentration over 0.4 mm. Duration of SO tamponade was positively correlated with IOL tilt (P = 0.014) and decentration (P < 0.001). The internal total higher-order aberration, coma, trefoil, and secondary astigmatism in the PPV group were higher than in the non-PPV group, and positively correlated with IOL tilt (P < 0.05). Conclusions: Patients with prior vitrectomy had greater IOL tilt and decentration than the non-PPV group. Longer duration of SO tamponade, hydrophilic IOL, as well as DM were the risk factors of greater IOL tilt and decentration in patients with prior PPV. Translational relevance: Optically sophisticated designed IOLs should be used cautiously in vitrectomized eyes.
Article
Purpose: To evaluate which ocular axis, the corneal topographic axis (CTA), pupillary axis (PA) or line of sight (LOS), for measuring the tilt and decentration of intraocular lens (IOL) is most relevant to correct distance visual acuity (CDVA). Methods: A Scheimpflug device (Pentacam HR) was prospectively used to determine the tilt and decentration of IOLs in vivo 3 months after cataract surgery. A new method was developed to reliably measure PA and LOS. We further evaluated CTA and then used Spearman correlation coefficient and linear regression to assess the correlation between CDVA and IOL displacement based on the data of three different ocular axes. Results: Forty-six eyes from 46 patients were evaluated. The majority of decentration and tilt of IOL with reference to CTA, PA and LOS were towards the subtemporal direction. We found that the horizontal meridian data measured using CTA and PA were statistically significantly different (p = 0.011 for tilt; p = 0.005 for decentration). The correlation between CDVA and the distance of decentration temporally (r = -0.344, p = 0.035) and inferiorly (r = -0.336, p = 0.042) of the IOL with regard to CTA was significant. PA and LOS measurements had no correlation with any indices. Conclusion: Assessment of tilt and decentration of the IOL with reference to different ocular axes was markedly different. IOL tilt and decentration measured by CTA were significantly correlated with CDVA.
Article
Purpose: The aim of the study was to examine whether air tamponade has a significant effect on postoperative tilt of the intraocular lens (IOL) in combined phacoemulsification with implantation of an IOL and vitrectomy compared to balanced salt solution. Procedures: This randomized, controlled, monocentre study included patients scheduled for combined phacoemulsification with IOL implantation and pars plana vitrectomy. Patients were randomized for balanced salt solution or air tamponade. Postoperative tilt and decentration of the IOL were measured 2 months after surgery with a Purkinje meter. Results: Thirty-four patients were included into the analysis. Tilt of the IOL was on average 4.1 ± 1.9°, without significant differences between balanced salt solution and air tamponade (p = 0.462). Decentration of the IOL was on average 0.31 ± 0.14 mm, without significant differences between balanced salt solution and air tamponade (p = 0.42). Conclusions: Air tamponade does not induce significantly more tilt or decentration of the IOL in combined phacoemulsification and vitrectomy compared to balanced salt solution. Potentially, this may not hold true for cases with a capsulorhexis that does not overlap the IOL optic.
Article
Full-text available
To evaluate intraocular lens (IOL) tilt and decentration by anterior segment optical coherence tomography (AS-OCT) using 3-dimensional (3D) reconstruction method. Prospective observational case series. Thirty-nine patients (39 eyes) were included. The IOL positions of all eyes were examined by AS-OCT. Images were obtained in 4 axes (0-180 degrees, 45-225 degrees, 90-270 degrees, and 135-315 degrees) using the quadrant-scan model. The cross-sectional images were analyzed with MATLAB software. The angle (θ) between the reference pupillary plane and the IOL plane, the distances between the center points of the pupil circle and the IOL on the x-axis (dx) and y-axis (dy) and the spatial distance (ds) were calculated after 3D-reconstruction. The mean angle (θ) between the pupillary plane and the IOL plane was 2.94±0.99 degrees. The mean IOL decentration of dx and dy was 0.32±0.26 mm and 0.40±0.27 mm, respectively. The ds of the IOL decentration was 0.56±0.31 mm. There was no significant correlation between the ocular residual astigmatism (ORA) and the tilted angle or the decentration distance. There was a significant correlation between the ORA and total astigmatism (r = 0.742, P<0.001). There was no significant correlation between the postoperative best corrected visual acuity (BCVA) and the ORA (r = 0.156; P = 0.344), total astigmatism (r = 0.012; P = 0.942), tilted angle (θ; r = 0.172; P = 0.295) or decentration distance (dx: r = 0.191, P = 0.244; dy: r = 0.253, P = 0.121; ds: r = 0.298, P = 0.065). AS-OCT can be used as an alternative for the analysis of IOL tilt and decentration using 3D-reconstruction.
Article
To study the reliability of Purkinje image analysis for assessment of intraocular lens tilt and decentration in pseudophakic eyes. The study comprised 64 eyes of 39 patients. All eyes underwent phacoemulsification with intraocular lens implanted in the capsular bag. Lens decentration and tilt were measured multiple times by an infrared Purkinjemeter. A total of 396 measurements were performed 1 week and 1 month postoperatively. Lens tilt (Tx, Ty) and decentration (Dx, Dy) in horizontal and vertical directions, respectively, were calculated by dedicated software based on regression analysis for each measurement using only four images, and afterward, the data were averaged (mean values, MV) for repeated sequence of measurements. New software was designed by us for recalculating lens misalignment parameters offline, using a complete set of Purkinje images obtained through the repeated measurements (9 to 15 Purkinje images) (recalculated values, MV'). MV and MV' were compared using SPSS statistical software package. MV and MV' were found to be highly correlated for the Tx and Ty parameters (R > 0.9; p < 0.001), moderately correlated for the Dx parameter (R > 0.7; p < 0.001), and weakly correlated for the Dy parameter (R = 0.23; p < 0.05). Reliability was high (Cronbach α > 0.9) for all measured parameters. Standard deviation values were 0.86 ± 0.69 degrees, 0.72 ± 0.65 degrees, 0.04 ± 0.05 mm, and 0.23 ± 0.34 mm for Tx, Ty, Dx, and Dy, respectively. The Purkinjemeter demonstrated high reliability and reproducibility for lens misalignment parameters. To further improve reliability, we recommend capturing at least six Purkinje images instead of three.
Article
This review was conducted to compare the physical effect of aspheric IOL implantation on wavefront properties with that of spherical IOL implantation. The peer-reviewed literature was systematically searched in Medline, Embase, Web of Science, Biosis, and the Cochrane Library according to the Cochrane Collaboration method. Inclusion criteria were randomized controlled trials comparing the use of aspheric versus spherical monofocal IOL implantation that assessed visual acuity, contrast sensitivity, or quality of vision. A secondary outcome was ocular wavefront analysis; spherical aberration, higher-order aberrations (HOAs), coma, and trefoil were evaluated. Effects were calculated as standardized mean differences (Hedges g) and were pooled using random-effect models. Thirty-four of 43 studies provided data for wavefront analysis. Aspheric monofocal IOL implantation resulted in less ocular spherical aberration and fewer ocular HOAs than spherical IOLs. This might explain the better contrast sensitivity in patients with aspheric IOLs. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.
Article
Importance Spectacle independence is becoming increasingly important in cataract surgery. Not correcting corneal astigmatism at the time of cataract surgery will fail to achieve spectacle independency in 20% to 30% of patients.Objective To compare bilateral aspherical toric with bilateral aspherical control intraocular lens (IOL) implantation in patients with cataract and corneal astigmatism.Design, Setting, and Participants A multicenter, hospital-based, randomized clinical trial was conducted. The participants included 86 individuals with bilateral cataract and bilateral corneal astigmatism of at least 1.25 diopters (D) who were randomized to receive either bilateral toric (n = 41) or bilateral control (n = 45) IOL implantation.Interventions Bilateral implantation of an aspherical toric IOL or an aspherical control IOL.Main Outcomes and Measures Spectacle independency for distance vision, uncorrected distance visual acuity, refractive astigmatism, contrast sensitivity, wavefront aberrations, and refractive error–related quality-of-life questionnaire.Results Preoperatively, mean (SD) corneal astigmatism was 2.02 (0.95) D and 2.00 (0.84) D in the toric and control groups, respectively. Four patients (5%) were lost to follow-up. At 6 months postoperatively, 26 (70%) of the patients in the toric group achieved an uncorrected distance visual acuity of 20/25 or better compared with 14 (31%) in the control group (P < .001; odds ratio, 5.23; 95% CI, 2.03-13.48). Spectacle independency for distance vision was achieved in 31 patients (84%) in the toric group compared with 14 patients (31%) in the control group (P < .001; odds ratio, 11.44; 95% CI, 3.89- 33.63). Mean refractive astigmatism was −0.77 (0.52) D and −1.89 D (1.00) D, respectively. Vector analysis of toric IOLs showed a mean magnitude of error of +0.38 D, indicative of overcorrection. No significant differences were found in contrast sensitivity, higher-order aberrations, or refractive error–related quality of life.Conclusions and Relevance In patients with cataract and corneal astigmatism, bilateral toric IOL implantation results in a higher spectacle independency for distance vision compared with bilateral control IOL implantation. No significant differences were identified in contrast sensitivity, higher-order aberrations, or refractive error–related quality of life following both treatments.Trial Registration clinicaltrials.gov Identifier: NCT01075542
Article
Since the origin of the high interindividual variability of the chromatic difference in retinal image magnification (CDM) in the human eye is not well understood, optical parameters that might determine its magnitude were studied in 21 healthy subjects with ages ranging from 21 to 58 years. Two psychophysical procedures were used to quantify CDM. They produced highly correlated results. First, a red and a blue square, presented on a black screen, had to be matched in size by the subjects with their right eyes. Second, a filled red and blue square, flickering on top of each other at 2 Hz, had to be adjusted in perceived brightness and then in size to minimize the impression of flicker. CDM varied widely among subjects from 0.0% to 3.6%. Biometric ocular parameters were measured with low coherence interferometry and crystalline lens tilt and decentration with a custom-built Purkinjemeter. Correlations were studied between CDM and corneal power, anterior chamber depth, lens thickness, lens tilt and lens decentration, and vitreous chamber depths. Lens thickness was found significantly correlated with CDM and accounted for 64% of its variance. Vertical lens tilt and decentration were also significantly correlated. It was also found that CDM increased by 3.5% per year, and part of this change can be attributed to the age-related increase in lens thickness.
Article
To quantify 3-dimensionally the anterior segment geometry, biometry, and lens position and alignment in patients before and after implantation of the Crystalens-AO (Bausch & Lomb, Rochester, NY) accommodating intraocular lens (A-IOL). Prospective, observational study. Ten patients (20 eyes) with cataract before and after implantation of the Crystalens-AO A-IOL. Custom full anterior segment 3-dimensional (3-D) spectral optical coherence tomography (OCT) provided with quantification tools was used to image the cornea, iris, and natural lens preoperatively and intraocular lens postoperatively. Measurements were obtained under phenylephrine preoperatively and under natural viewing conditions and phenylephrine (for accommodative efforts ranging from 0 to 2.5 diopters [D]) and pilocarpine postoperatively. Three-dimensional quantitative anterior segment images, corneal geometry and power, anterior chamber depth (ACD), lens thickness, pupil diameter, A-IOL shift with accommodative effort or drug-induced accommodation, and A-IOL alignment. Crystalline lens and IOLs were visualized and quantified 3-dimensionally. The average ACD were 2.64±0.24 and 3.65±0.35 mm preoperatively and postoperatively (relaxed state), respectively, and they were statistically significantly correlated (although their difference was not statistically correlated with lens thickness). The A-IOL did not shift systematically with accommodative effort, with 9 lenses moving forward and 11 lenses moving backward (under natural conditions). The average A-IOL shift under stimulated accommodation with pilocarpine was -0.02±0.20 mm. The greatest forward shift occurred bilaterally in 1 patient (-0.49 mm in the right eye and -0.52 mm in the left eye, under pilocarpine). The high right/left symmetry in the horizontal tilt of the crystalline lens is disrupted on IOL implantation. Accommodative IOLs tend to be slightly more vertically tilted than the crystalline lens, with increasing tendency with accommodative effort. Two subjects showed postoperative IOL tilts >9 degrees. Changes in pupillary diameter correlated with pilocarpine-induced A-IOL axial shift. Intermediate accommodative demands (1.25 D) elicited the greater shifts in axial A-IOL location and tilt and pupil diameter. Quantitative 3-D anterior segment OCT allows full evaluation of the geometry of eyes implanted with A-IOLs preoperatively and postoperatively. High-resolution OCT measurements of the Crystalens 3-D positioning revealed small (and in many patients backward) A-IOL axial shifts with both natural or drug-induced accommodation, as well as tilt changes with respect to natural lens and accommodative effort. Proprietary or commercial disclosure may be found after the references.
Article
The improved designs of intraocular lenses (IOLs) implanted during cataract surgery demand understanding of the possible effects of lens misalignment on optical performance. In this review, we describe the implementation, set-up and validation of two methods to measure in vivo tilt and decentration of IOLs, one based on Purkinje imaging and the other on Scheimpflug imaging. The Purkinje system images the reflections of an oblique collimated light source on the anterior cornea and anterior and posterior IOL surfaces and relies on the well supported assumption of the linearity of the Purkinje images with respect to IOL tilt and decentration. Scheimpflug imaging requires geometrical distortion correction and image processing techniques to retrieve the pupillary axis, IOL axis and pupil centre from the three-dimensional anterior segment image of the eye. Validation of the techniques using a physical eye model indicates that IOL tilt is estimated within an accuracy of 0.261 degree and decentration within 0.161 mm. Measurements on patients implanted with aspheric IOLs indicate that IOL tilt and decentration tend to be mirror symmetric between left and right eyes. The average tilt was 1.54 degrees and the average decentration was 0.21 mm. Simulated aberration patterns using custom models of the patients eyes, built using anatomical data of the anterior cornea and foveal position, the IOL geometry and the measured IOL tilt and decentration predict the experimental wave aberrations measured using laser ray tracing aberrometry on the same eyes. This reveals a relatively minor contribution of IOL tilt and decentration on the higher-order aberrations of the normal pseudophakic eye.
Article
To compare intraocular lens (IOL) decentration and tilt following a circular capsulotomy created with a femtosecond laser (laser CCC) to a manually performed continuous curvilinear capsulorrhexis (manual CCC). In a prospective, randomized study, a laser CCC (Alcon LenSx Inc) was performed in 20 eyes from 20 patients and a manual CCC was performed in 25 eyes from 25 patients. Intraocular lens decentration and tilt were measured using a Scheimpflug camera (Pentacam, Oculus Optikgeräte GmbH) 1 year after surgery. Uncorrected (UDVA) and corrected distance visual acuity (CDVA) and manifest refraction were also determined postoperatively. Between-group differences of IOL decentration and tilt as well as the correlation between IOL decentration and postoperative refractive changes and between IOL tilt and visual acuity were analyzed. Horizontal and vertical tilt were significantly higher in the manual CCC group (P=.007 and P<.001, respectively). Lenses implanted after manual CCC showed greater horizontal and total decentration (P=.034 and P=.022, respectively). Significant differences were found in the homogeneity of dichotomized IOL vertical tilt and both horizontal and total decentration distribution (P=.008, P=.036, and P=.017, respectively). Total IOL decentration showed a significant correlation with changes in manifest refraction values between 1 month and 1 year after surgery (R=0.33, P=.032). A significant correlation was noted between IOL vertical tilt and CDVA (R(2)=0.17, β=-0.41, 95% confidence limit: -0.69 to -0.13, P=.005). Continuous curvilinear capsulorrhexis created with a femtosecond laser resulted in a more stable refractive result and less IOL tilt and decentration than manual CCC.
Article
To assess the effect of intraocular lens (IOL) orientation (vertical versus horizontal) and haptic design (1-piece versus 3-piece) on centration and tilt using a Purkinje meter. Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom. Randomized pilot study with intrapatient comparison. In part 1 of this study, patients received plate-haptic IOLs (Akreos Adapt) in both eyes that were positioned vertically in 1 eye and horizontally in the other eye. In part 2, patients received a 1-piece IOL (Acrysof SA60AT) in 1 eye and a 3-piece IOL (Acrysof MA60AC) in the contralateral eye. Decentration and tilt were measured 1 month and 3 months postoperatively with a new Purkinje meter. In part 1 (n = 15), the mean decentration of plate-haptic IOLs was 0.4 mm ± 0.2 (SD) with vertical orientation and 0.4 ± 0.2 mm with horizontal orientation and the mean tilt, 1.5 ± 1.1 degrees and 2.9 ± 0.9 degrees, respectively. In part 2 (n = 15), the mean decentration was 0.4 ± 0.3 mm with 1-piece IOLs and 0.6 ± 0.8 mm with 3-piece IOLs and the mean tilt, 2.2 ± 7.2 degrees and 5.3 ± 2.4 degrees, respectively. Three-piece IOLs had a greater tendency toward more decentration than 1-piece IOLs, perhaps because of slight deformation of 1 or both haptics during implantation or inaccuracies in production when the haptics are manually placed into the optic. The IOL orientation for plate-haptic IOLs appeared to have no effect on IOL position. The Purkinje meter was useful in assessing the capsule bag performance of the IOLs. No author has a financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes.
Article
To determine the ability of anterior segment optical coherence tomography (OCT) to detect intraocular lens (IOL) tilt evaluation in relation to the limbus. Observational case series. The IOL position of 123 eyes of 92 patients was examined with anterior segment OCT (Carl Zeiss Meditec, Dublin, California, USA). All eyes underwent uneventful phacoemulsification with the IOL in the bag. Images were obtained in 4 axes (180 to 0 degrees, 225 to 45 degrees, 315 to 135 degrees, and 270 to 90 degrees). Using MatLab software version 7.1 (Mathworks), the OCT images were analyzed. The distance between the iris margin and the anterior surface of IOL, the slope ratio between IOL and limbus, and the angle (θ; position of IOL with reference to the limbus) were determined and were correlated with the astigmatism and vision. The mean slope of the limbus and the IOL in all axes was 0.003 ± 0.09 and -0.002 ± 0.12, respectively. The average slope ratio was 1.1 ± 1 (range, -2.09 to 3.82) and the angle (θ) was 1.52 ± 0.9 degrees (range, 0.04 to 3.6 degrees). The mean ocular residual astigmatism was 0.2379 ± 0.469 diopters. There was no significant correlation of ocular residual astigmatism with slope ratio (r = -0.171; P = .060) and slope angle (r = -0.132; P = .147). There was significant correlation of ocular residual astigmatism with total astigmatism (r=0.602, p=0.000). The mean distances between the iris margin and the anterior surface of IOL at the pupillary plane were 0.80 ± 0.6 mm and 0.83 ± 0.57 mm, respectively. The normal in-the-bag IOL maintains an angle with reference to the limbus and a slope ratio without causing a significant tilt. Anterior segment OCT can be used as an alternative in IOL tilt evaluation by the analysis of its position in relation to the limbus.