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NR 4-6/2008
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The effectiveness of
phacodeepsclerectomy performed with implantation Sk-gel and
T-flux – 12 months observations
Skuteczność sklerektomii
głębokiej z implantacją Sk-gel i T-flux
w 12-miesięcznej obserwacji
Marek Rękas, Joanna Wierzbowska,
Katarzyna Lewczuk, Anna Siemiątkowska, Andrzej Stankiewicz
Departament of Ophthalmology, Military Health Service Institute
in Warsaw
Head: Professor Andrzej Stankiewicz, MD, PhD |
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| Summary: |
Purpose: The
purpose of this work was to present effectiveness and
safety of phacodeepsclerectomy with SK-gel and T-flux
implant in 12 months observation.
Materials and methods: Retrospective analysis
included group I (SK-gel) – 40 eyes and group II (T-flux)
– 23 eyes. At the control studies best corrected visual
acuity (BCVA), intraocular pressure (IOP), anterior and
posterior segment of the eye were examined. Control
testing was done in the first day and 7-th day, and 1,
3, 6, 12 months after surgery. In the case of elevated
IOP (>15 mmHg) goniopuncture was performed. IOP (>15
mmHg) with fibrosis signs of the filtration bleb was an
indication to use antimetabolites. Complete and
qualified success rate was defined as IOP≤18 mmHg. In
statistical analysis one-way ANOVA and Kaplan-Meier
survival analysis, were used.
Results: After 12 months mean IOP in the SK-gel
group was 12.7 ± 0.6 mmHg and in T-flux group 14.6 ± 0.7
mmHg. It was a decrease in the mean IOP by 39.1%
(p<.001) and 35.7% (p<.001). In both groups fewer
medications were used than before surgery. Complete
surgical and qualified success rate was reached in group
I (81.7% and 91.9%) and in group II (72.7% and 83.8%).
Nd:YAG goniopuncture performed in 10 eyes with implant
SK-gel (25.0%) and 6 eyes with implant T-flux (26.1%)
(p>.05). Subconjunctival injections with 5-FU were done
in 5 eyes in the SK-gel group (12.5%) and in 3 eyes in
the T-flux group (13.0%) (p>.05).
Conclusions: Phacodeepsclerectomy (PDS) with
SK-gel and T-flux implant are both effective and safe
surgical methods in the treatment of POAG in 12 months
observation. |
| Słowa kluczowe: |
sklerotomia głęboka,
implanty wchłanialne, implanty niewchłanialne. |
| Key words: |
phacodeepsclerectomy;
absorbable implants; non-absorbable implants. |
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Introduction
Correctly functional filtration membrane comprised of Descemet’s
membrane and Schlemm’s canal with outer wall removed during
surgery, as well as decompression space maintained in the sclera
and functional drainage of the aqueous fluid are determined
about the effectiveness of deep sclerectomy (DS). Decompression
space maintains negative pressure in relation to anterior
chamber, which enables its decompression. On the other hand it
serves as specific retention cistern on the way of aqueous fluid
drainage pathway from the anterior chamber. Maintenance of
decompression space in the sclera is one of the conditions of
correctly functioning deep sclerectomy. Non-perforating
techniques presented at first by Epstein and Krasnow at the end
of fifties in the past century, improved later in the eighties
by Russian school (Fiodorow, Kozlow) and North American school (Zimmerman),
were for many years in the shadow of classical trabeculectomy as
less effective. The progress of non-perforating glaucoma surgery
was possible not only due to the progress in eye microsurgery,
but also due to new biotechnology achievements. Nowadays to fix
the created decompression space the use of different implants in
the scleral bed is performed. The advantage of DS with the use
of scleral implants over classical surgery is pretty obvious at
this time (1-4). The first used implants were obtained from
freeze-dried bovine collagen (Aquaflow). The most popular among
the absorbable implants is SK-gel, which is a biosynthetic
Sodium hialuronate. In UBM studies it is confirmed the
reabsorption from the scleral bed after about 4 months from
surgery in hialuronic implants and 6 to 9 months after collagen
implants (5). Absorbable implants leave a large niche with a
capacity of about 6-8 mm3 as a result of reparation processes in
the sclera. At present non-absorbable implants T-flux are used
as well made of hydrophilic acryl. This type of implant is
placed in scleral bed and fixed with one suture to its fundus.
Fixing the implant enables insertion of its ends into Schlemm’s
canal, which is important in facilitation of drainage from
decompression space in physiological way. From the other point
the capacity of decompression space is diminished by the
capacity of implant itself, and reparation processes in the
sclera being the reaction to the foreign body may be the cause
of unfavorable final effect of the surgery.
Materials and methods
Retrospective analysis included two groups of patients after
phacoemulsification combined with DS performed in the Department
of Ophthalmology, Military Health Service Institute in Warsaw
from October 2003 to November 2004. Group I comprised of 36
patients (40 eyes, 21 females and 15 males) after sclerectomy
with SK-gel implant into the scleral bed. 23 patients (23 eyes,
19 females and 4 males) qualified to group II, who received
T-flux implant.
The indication for surgery was open-angle glaucoma, treated with
at least two medications without satisfactory control of IOP or
with the progression of changes in the visual field. Cataract
was removed with phacoemulsyfication method.
Pre-operation testing included: BCVA, applanation tonometry,
gonioscopy, pachymetry, examination of the anterior chamber in
biomicroscope, fundoscopic exam, perimetry with threshold
strategy with the use of computerized perimeter Centerfield/
Oculus.
Surgeries performed by one surgeon (MR), were done with
retrobulbar anesthesia with 2% Xylocaine supported by NLA. After
the cut off of bulbar sclera from the corneal limbus in the
upper quadrant, square flap from superficial sclera was
separated, measuring 5 x 5 mm with the base in the limbus. Later
in the deep layer of sclera, square flap, measuring 3.5 x 3.5
mm, was separated reaching spurs of sclera. Phacoemulsification
was performed through the clear corneal temporal incisions. IOL
was placed in the capsule. Further deep flap of sclera was
separated showing Schlemm’s canal and Descemet’s membrane
comprising the filtration membrane, (trabecular-Descemet`s
membrane). Deep flap of the sclera was cut off at the Schwalbe
line and outer wall of the Schlemm’s canal, was removed. After
the placement of the implant into the scleral bed (acrylic
implant was additionally sutured with Nylon 10-0, the
superficial flap was closed with single stitches Nylon 10-0 and
conjunctival opening was closed with single stitches Vicryl 8-0.
In control testing BCVA, IOP, anterior chamber and fundus were
examined, postoperative course was analyzed with complications
and procedures used to fix hypotensive effect (goniopuncture,
antimetabolites), as well as number of used medications. Testing
was done 1 and 7 days after surgery and later after 1, 3, 6 and
12 months. In the case of increased IOP (>15 mmHg) caused by the
failure of the filtration membrane (lack or poorly developed
filtration bleb), goniopuncture was performed with laser Nd:YAG.
Elevated IOP (>15 mmHg) with signs of inflammation or fibrosis
of the filtration bleb was the indication to use antimetabolites.
5-flurouracyl (5-FU) was used as 5 mg subconjunctival injection,
180 degrees from the surgical wound in the area of inferior
conjunctival crease. Injections were given daily for five
consecutive days and as needed were repeated after a week.
Antimetabolites were discontinued earlier when good regulation
of IOP was achieved or complications appeared. During the first
four weeks after operation all the patients received antibiotic
with steroids with non-steroidal anti-inflammatory agent into
the conjunctival sac.
Complete surgical success rate was defined as IOP≤18 mmHg
without anti-glaucoma medications and qualified success rate as
IOP≤18 mmHg without and with medications. Statistical analysis
was done with the U Mann-Whitney’s test, t-Student’s test, pair
sequence Wilcoxon’s test and variance was analyzed (one-way
ANOVA) and chi square test. Survival analysis was assessed with
Kaplan-Meier method with the use of log rank test.
Results
Studied groups were homogenous according to age, sex and
original IOP (p>.05) (Tab. I). The mean time of observation was
360 days in both groups.
IOP control
The mean IOP in the SK-gel group was 21.1 ± 1.3 (SE) mmHg and
was decreased in day 1-st after surgery by 49.8% and was 10.6 ±
1.0 (SE) mmHg (p<.001). In the group T-flux the mean IOP in day
1 after surgery was decreased by 53.7% from original 22.7 ± 1.5
(SE) mmHg to 10.5 ± 1.1 (SE) mmHg (p<.001). After 360 days of
observation the mean values of IOP in SK-gel group was 12.7 ±
0.6 (SE) mmHg and in T-flux group 14.6 ± 0.7 (SE) mmHg. It was
decrease in the mean IOP by 39.1% (p<.001) and 35.7% (p<.001)
respectively in relation to pre-surgical values in particular
groups
Medications
In both groups after surgery fewer medications were used than
before surgery and the results were statistically significant
(p<.05) (Tab. II). In SK-gel group at the end of observation, 33
eyes (82.5%) did not require medications. In T-flux group 69.6%
(16 eyes) did not require medications at the same time after
operation. There was no statistical difference between numbers
of used medications in both studied groups at the end of
observation (Tab. II).
Surgical success
Complete success rate was achieved when IOP was ≤18 mmHg 360
days after surgery without medications and qualified success
rate was with IOP≤18 mmHg without medications or with maximum
two medications. Cumulated success probability based on the
above criteria for the particular periods of observation is
shown in Tab. III. Graphs of Kaplan-Meier survival analysis for
qualified and complete surgical success rate criteria are shown
in figure 2. In the entire observation period there were no
statistically significant differences between
SK-gel group and T-flux group (p>.05)
BCVA
The mean visual acuity in SK-gel group was changed from 0.52 ±
0.29 before surgery to 0.47 ± 0.30 in the first day after
surgery, 0.73 ± 0.28 after a month and maintaining this value in
the subsequent tests (p<.05). The mean visual acuity in
T-flux group changed from 0.49 ± 0.24 before surgery to 0.80 ±
0.19 at the end of observation (p<.05). For all the tests there
was no statistically significant difference between mean visual
acuity in groups I and II (p>.05)
Goniopuncture, antimetabolites
Goniopuncture with Nd:YAG laser was performed in 16 eyes,
including 10 eyes with SK-gel implant (25.0%) and in 6 eyes with
T-flux implant (26.1%) (p>.05). Subconjunctival injections with
5-FU was done in 5 eyes in SK-gel group (12.5%) and 3 eyes in
T-flux group (13.0%) (p>.05). The mean time to begin the
treatment with antimetabolites was 11.2 days (range 2-16 days)
from surgery in SK-gel group and 17.0 days (range 13-20 days) in
T-flux group; the mean dosages of 5-FU was 17.0 mg and 13.3 mg
respectively and mean number of injections was 3.4 (range 1-6)
vs. 2.7 (range 2-4).
Complications
Early complications included: transient hypotonia (<6 mmHg) in
10 eyes in SK-gel group (25.0%) and 4 eyes in T-flux group
(17.4%) (p>.05), increased IOP (>20 mmHg) in 3 eyes in group I
(7.5%) and 4 eyes in group II (17.4%) (p>.05), inflammatory
exudates in 2 eyes in group I (5.0%) and 1 eye in group II
(4.3%), bleeding into the anterior chamber in 2 eyes in SK-gel
group and 1 eye in T-flux group (5.0% vs. 4.3%) (p>.05),
shalowing of the anterior chamber in 2 eyes in group I (5.0%),
choroid detachment in 1 eye of both groups (2.5% vs. 4.3%) and
vitreous hemorrhage in 1 eye in group I (2.5%). Late
complications included: fibrosis of the filtration bleb in 8
eyes in group I (20.0%) and 5 eyes in group II (21.7%) (p>.05),
macular edema in 1 eye of both groups (2.5% vs. 4.3%) (p>.05)
and the peripheral iris incanceration in 1 eye in T-flux group
(4.3%) that underwent goniopuncture with Nd:YAG laser.
Complications with antimetabolites pertained to 7 eyes in both
groups and were transient corneal epitheliopathy – in 3 eyes of
both groups (7.5% vs. 13%) and induction of irregular
astigmatism– in 1 eye in T-flux group (4.3%).
Discussion
Sudden decompression of the eyeball associated with classical
trabeculectomy is prone for significant risk of complications
as: hypotonia, anterior chamber shallowing or decrease in visual
acuity. This fact was not left without the influence on laying
grounds in the past few decades of traditional approach to
glaucoma therapy, which treats the surgery as a last resort in
the sequence of therapeutic options in glaucoma. The change of
the philosophy in the therapy of glaucoma and earlier
application of surgical modalities-among the others as an
alternative for compound pharmacological treatment would be
possible with the rise of the safety profile level of the
surgical technique, and simultaneously maintaining its high
effectiveness. Conditions for safe and effective surgery are met
by DS with its modifications, tied with the usage of different
scleral implants and pharmacological strategy of tissue
regeneration.
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Implant, which is
fulfilling decompression space between the separated scleral
tissues, is fixing decompression space and preventing the
fibrosis of the filtration space, is increasing drainage of the
aqueous fluid from Schlemm’s canal and contributes to greater
reduction of IOP. The implant is also helpful in development of
the filtration bleb, very infrequently observed in
non-perforating surgery without the use of implants (60% vs.
5%), is facilitating supra-choroid drainage and is stimulating
production of new scleral vessels, draining the aqueous fluid
(6,7). Nowadays the absorbable implants are used, made of
collagen or sodium hialuronate, non-absorbable acrylic implants
or monofilament chromic sutures, as the last ones bioimplants
were introduced from the amniotic sac membrane or autologous
sclera. The reason to use non-absorbable implants is to maintain
constant decompression space under superficial scleral flap and
extension of the effectiveness of nonperforating surgery. This
is confirmed by 30-months observation by Dahan (8), who did not
notice any statistically significant differences in reduction of
IOP between the eyes with T-flux implant and the eyes without
the implant in the first 18 months after surgery, but during the
course of further observation (from 23rd month), stable profile
of reduction of IOP was noted only in eyes with implant (62% vs.
32%). The positive effect of implants on the level of reduction
of IOP in the light of up to date studies seems to be
unquestionable (6,8,9), but very few studies pertains to
comparative analysis (10,11).
The purpose of this work was to show effectiveness and safety of
deep phacosclerectomy with absorbable implant made of sodium
hialuronate (SK-gel/ Corneal) or non-absorbable acrylic implant
(T-flux/ IOLTech), in the material of the Department of
Ophthalmology, Military Health Service Institute in Warsaw based
on 12-months observation.
In 1-st day after surgery the mean IOP was decreased by 49.8% in
the SK-gel group and 53.7% in T-flux group, there was no
statistically significant difference between groups. Greater
reduction of IOP (by 84%) in the first day after surgery in eyes
with T-flux implant noted Dahan (8), who thought that this
positive sign is a proof of increased permeability of the
trabecular texture preparation. In our own material early
transient hypotonia (<6 mmHg) was observed in 25% of eyes with
SK-gel implant and 17.4% eyes with T-flux implant. According to
Shaarawy (12), hypotonia below 6 mmHg in the first day after
surgery has a positive prognostic value of the far-reaching
surgical success. In this work, after 12 months of observation
reduction of the mean IOP was 39.1% in SK-gel group and 35.7% in
T-flux group in comparison to pre-surgery values. Complete
surgical success rate was achieved by 81.7% of eyes in SK-gel
group and in 72.7% of eyes in T-flux group and qualified success
rate in 91.9% and 83.8% of eyes respectively. The tendency that
was observed in our own studies of smaller reduction of IOP in
eyes with T-flux implant does not confirm the main advantages of
the non-absorbable implant and cited before work by Dahan (8)
and maybe it has a connection with gradual shrinking of the
decompression space as a fibrotic reaction to the foreign body
that is an implant. Histopathological tests on rabbits showed
that a condition of effective sclerectomy is maintenance of a
large and regular intrascleral lake with the lack of tissue
destruction, fibrosis and inflammation (13). It was noted that
in eyes with the collagen implant the walls of the lake are
selectively covered with spindle cells (this process begins two
months after the operation and ends after nine months), without
simultaneous infiltration by mononuclear cells (7). The
induction of inflammatory processes and fibrosis in the
decompression space is observed in eyes with an implanted
chromic suture (13); theoretically these processes cannot be
excluded in the case of an acrylic implant, which requires
additional intraoperative manipulations that traumatize the
tissues such as suturing of the implant or fixing its branches
in Schlemm’s canal.
Up to now the comparison of the effectiveness of DS with the use
of sodium hialuronate implant (SK-gel/ Corneal) or acrylic
implant (T-flux/ IOLTech), was the topic of very few
publications. Detry-Morel (10) in the material of 20 eyes,
complete surgical success rate (defined as achievement of
individual level of goal pressure without medications and
without goniopuncture Nd:YAG), noted in 80% of eyes in SK-gel
group and in 60% of eyes in T-flux group, and qualified success
rate (with medications and goniopuncture Nd:YAG) in 100% and 80%
of eyes respectively. The mean IOP after 7 months of observation
was lower by 46.5% than the value before surgery and no
statistical difference was observed between groups. Drosum (11),
comparing non-absorbable acrylic implant (T-flux/ IOLTech) with
absorbable collagen implant (Aquaflow/ Staar Surgical) did not
find any statistical differences between the groups after 6
months observation (14.8 vs. 16.4 mmHg). Studies by other
authors confirm as well high effectiveness of DS with usage of
the above-mentioned implants. Ravinet (14), in longer, 24 months
observation noted on average 53% reduction of IOP in eyes with
acrylic implant T-flux and surgical success defined as IOP< 15
mmHg without medications was achieved in 81.8% of eyes. Ates
(15) using the same implant complete surgical success rate
(IOP<21 mmHg without medications) noted in 86.9% of eyes after
one month from surgery and in 56.5% after 12 months. Drosum (11)
noted higher percentage of the effectiveness of DS with the use
of T-flux in eyes with pseudoexfoliating glaucoma than primary
open-angle glaucoma (IOP<19 mmHg without medications in 61% of
eyes vs. 38%) after 18 months observation. In studies with the
use of sodium hialuronate implants (SK-gel) the mean IOP was
lower by 41-47% after 12 months (16,17) as well as after 30
months from surgery (10).
In the case of filtration membrane failure and IOP above 15 mmHg
goniopuncture with Nd:YAG laser was done. In our own material
there was no statistical difference between groups.
Goniopuncture Nd:YAG was used in 10 eyes in SK-gel group (25%)
and in 6 eyes in T-flux group (26.1%) and it was performed in
the first month after operation. Other authors report similar or
higher percentage of the use of this procedure: 13.0-63.6% for
eyes with acrylic implant (8,14,15) and 16.6% for sodium
hialuronate implant (10).
In our own studies, fibrosis and encapsulation of the filtration
bleb was observed in similar prevalence in both groups-in 20.0%
of eyes with SK-gel implant and 21.7% of eyes with T-flux
implant and percentage was lower than reported by other authors
(28.5%) (10). The treatment of choice in these cases were
subconjunctival injections with 5-FU, the mean dosage 17.5 mg in
SK-gel group and 13.3 mg in T-flux group and was lower than
recommended by Fluorouracil Filtering Surgery Study Group (18)
minimal dose (35 mg). Observed side effects after
antimetabolites injections were transient in character and there
was no difference between groups.
Applied surgical therapy enabled discontinuation of medications
in 82.5% of patients in SK-gel group and 69.6% of patients in
T-flux group. The mean number of medications was decreased from
2.4 before surgery to 0.26 after 12 months from the operation in
the group of eyes with absorbable implant and from 2.3 to 0.4 in
the group of eyes with non-absorbable implant. There was no
statistical difference between groups. Drosum (11) did not
observe any differences as well for acrylic implant T-flux and
collagen implant Aquaflow (0.6 vs. 0.7). The stable hypotensive
effect of DS was confirmed as well by Dahan, who noted complete
discontinuation of medications at the end of two-year
observation (3.4 vs. 0.0) and for SK-gel implant, Ravinet (14)
(2.5 vs. 0.4).
In our own studies deep phacosclerectomy with the use of
implants SK-gel or T-flux were shown to be equally safe. The
presence of blood in the anterior chamber, noted in 5.0% of
patients with SK-gel implant and 4.3% of patients with T-flux
implant, was probably a consequence of its reverse flow from the
scleral bed through trabeculation or micro perforations of the
filtration membrane. Vitreus hemorrhage observed in the first
day after surgery in one patient, was a consequence of central
retinal vein thrombosis. Other complications (anterior chamber
shallowing, choroid detachment, inflammatory exudates, macular
edema) did not differ between groups, were encountered rarely
(2-3%) and had a reversible character.
Deep phacosclerectomy with absorbable implant SK-gel
or non-absorbable implant T-flux is effective and safe method
of surgical therapy of open-angle glaucoma
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Praca włynęła do redakcji 30.06.2006 r. (859)
Zakwalifikowano do druku 26.03.2008 r.
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