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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.
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).
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ｮ SA60AT, Alcon
Laboratories, Inc.) for 2 years after surgery.
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.
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.
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
Nd:YAG 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.
PCO Value
1. Changes in mean (SD) posterior PCO value in the hydrogel
and acrylic IOL groups.
(CCT)
40
35
30
25
20
15
10
5
0
SA60AT
＊ P<0.01
HP60M
＊
1
week
＊
1
3
6
12
18
24
month months months months months months
Time after surgery
The PCO value in the hydrogel group increased significantly(p<0.01), 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.
2. Kaplan-Meier survival plots of the two groups for eyes not
requiring Nd:YAG laser posterior capsulotomy.
(%)
63 eyes
1 eye
Survival rate
100
8 eyes
80
60
SA60AT
40
HP60M
20
0
5
10
15
20
25
(months)
Time after surgery
The survival curve in the hydrogel group was significantly worse than that in the
acrylic group (p<0.01, Mantel-Cox log rank test).
3. Changes in mean (SD) visual acuity in the hydrogel and
acrylic IOL groups.
Time after surgery
Visual Acuity
20/15
1
week
1
6
12
18
24
month months months months months
SA60AT
HP60M
20/20
20/25
＊
＊
＊P<0.01
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.
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 epithelial–mesenchymal 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.
Conclusion
The hydrophilic IOL HP60M resulted in significantly 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.