Posterior Capsule Opacification After Implantation of Hydrophilic or Hydrophobic Acrylic IOL

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Posterior Capsule Opacification After
Implantation of Hydrophilic or Hydrophobic
Acrylic IOL
Takeshi Iwase, MD, PhD Wilmer Eye Institute Johns
Hopkins Hospital
The author has no financial or proprietary
interest.
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Introduction
Posterior capsule opacification (PCO) is still
the most common complication of primary cataract
surgery. Many kinds of IOLs composed of various
different optic materials have been developed to
prevent PCO. The one of hydrophilic IOLs
currently available worldwide is Hydroview IOL
(H60M and HP60M, Bausch Lomb) and several
studies reported that patients with hydrophilic
IOLs developed greater PCO than with other optic
materials. However, there is an important
limitation in those studies, most of them
compared between hydrophilic IOLs with round
optic edge and hydrophobic with sharp optic edge
or the observation period is relatively short
(under 2years).
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Purpose
Recently, a new developed Hydroview IOL HP60M is
introduced to prevent PCO by having sharp optic
edge, double square-edge. To our best knowledge,
there is no report to compare hydrophilic double
square-edged Hydroview IOL HP60M with other IOL.
The objective of this prospective study was to
evaluate the influence of hydrophilic
single-piece foldable acrylic square-edged IOLs
on the development of PCO, compared with
hydrophobic IOL (AcrySof? SA60AT, Alcon
Laboratories, Inc.) for 2 years after surgery.
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Patients
126 eyes of 63 patients with bilateral senile
cataract and no other ocular diseases were
prospectively randomized to receive a hydrophobic
acrylic (SA60AT) or hydrophilic acrylic single
piece IOL (HP60M). All patients were followed
for twenty-four months after the surgery.
Exclusion criteria were ocular pathology other
than senile cataract, history of intraocular
surgery, a pupillary diameter less than 6.0 mm
after full dilation, uveitis, retinitis
pigmentosa, pseudoexfoliation syndrome glaucoma,
and axial length longer than 25 mm or shorter
than 21 mm. Incomplete CCC included anterior
capsular crack formation and incomplete overlap
of the IOL optic.
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Surgery
A 3.0 mm wide self-sealing temporal sclerocorneal
tunnel was created. The anterior chamber was
filled with a viscoelastic material, and a 5.0 mm
to 5.25 mm CCC, slightly smaller than the IOL
optics diameter, was made to attain
circumferential 360-degree capsulorhexis-IOL
overlap. Thorough hydrodissection,
phacoemulsification of the nucleus, and
aspiration of the residual cortex was performed.
The wound was not enlarged and the SA60AT and
HP60M IOLs were inserted in the capsular bag
using the Monarch II injector. Postoperatively,
all patients received similar routine medication,
comprising topical application of diclofenac
sodium, 0.1 fluorometholone and ofloxacin
administered four times daily for 1 month.
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Methods

1. Changes in mean posterior PCO value in the HP60M
   and SA60AT groups.

The PCO density value was measured using
Scheimpflug video photography (EAS-1000, NIDEK)
at 1, 6, 12, 18, and 24 months after surgery.
2. Kaplan-Meier survival plots of the two
groups for eyes not requiring NdYAG laser
posterior capsulotomy.
The number of eyes that required capsulotomy were
also examined..
3. Changes in mean (SD) visual acuity in the
HP60M and SA60AT groups.
Best corrected visual acuity on decimal charts
was recorded at each visit and this acuity was
converted to logMAR for statistical analysis.
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1. Changes in mean (SD) posterior PCO value in the
   hydrogel and acrylic IOL groups.

SA60AT
(CCT)

Plt0.01
40
HP60M
35
PCO Value
30
25


20
15
10
5
0
12 months
6 months
18 months
24 months
3 months
1 month
1 week
Time after surgery
The PCO value in the hydrogel group increased
significantly(plt0.01), while the change in the
PCO value was not significant in the acrylic
group. The mean PCO value in the hydrogel IOL
group was significantly greater than that in the
acrylic group 18 and 24 month after surgery.
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2. Kaplan-Meier survival plots of the two
groups for eyes not requiring NdYAG laser
posterior capsulotomy.
The survival curve in the hydrogel group was
significantly worse than that in the acrylic
group (plt0.01, Mantel-Cox log rank test).
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3. Changes in mean (SD) visual acuity in the
hydrogel and acrylic IOL groups.
Time after surgery
1 week
12 months
6 months
1 month
18 months
24 months
20/15
SA60AT
20/20
HP60M
Visual Acuity
20/25



Plt0.01
20/40
Mean visual acuity in the hydrogel group was
worse than that in the acrylic group this
difference was significant at 18 and 24 months
after surgery.
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Discussion
Because the IOLs were implanted using same
surgical technique and have similar IOL optic
design such as sharp edge and diameter of 6 mm,
the degree of PCO in the both groups was mainly
related to the different IOL materials. Both the
sharpness of the bend and the speed of its
formation are important factors for PCO and the
differences in speed may be influenced by the IOL
material. In hydrophilic IOL, there is less
epithelialmesenchymal transition in LECs with
this more biocompatible material. As a result,
there may be less contraction-induced reduction
in the size of the residual capsular bag, which
would leave space and allow cells to migrate onto
the inner surface of the posterior capsule before
the posterior capsule adheres to the posterior
surface of the IOL. Furthermore, it was reported
that histopathologic and TEM evaluations of
hydrogel IOLs showed the hydrophilic surface
properties provide an optimum matrix for LECs and
cortical proliferation and migration from the
equatorial region toward the center of the visual
axis, leading to the higher degree of PCO.
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Conclusion
The hydrophilic IOL HP60M resulted in
signi?cantly more PCO 2 years after surgery
compared with the hydrophobic acrylic IOL SA60AT.
The results of previous and current studies
suggest that hydrophilic material may allow
active proliferation of lens epithelial cells,
possibly because of its hydrophilicity, and
therefore may not be appropriate for use as an
optic material. Further study is needed to
examine the extent of PCO with the other types of
IOL that have hydrophilic properties.