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NR 1-3/2008
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Cataract
phacoemulsification and intraocular pressure in glaucoma
patients
Fakoemulsyfikacja zaćmy a
ciśnienie wewnątrzgałkowe u chorych z jaskrą
Andrzej Mierzejewski, Iwona Eliks,
Bartłomiej Kałużny, Maja Zygulska,
Bartosz Harasimowicz, Jakub J. Kałużny
From the Department of Ophthalmology, Collegium Medicum,
Nicolaus Copernicus University, Bydgoszcz, Poland
Head: Professor Józef Kałużny, MD, PhD
From Department of Ophthalmology, Ludwik Perzyna’s Hospital,
Kalisz, Poland
Head: Jacek Urbaniak, MD |
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| Summary: |
Purpose: To
evaluate the influence of recently performed cataract
phacoemulsification in glaucomatous eyes on
postoperative intraocular pressure (IOP).
Material and methods: 100 eyes of 86 glaucoma
patients who underwent cataract phacoemulsification with
simultaneous intraocular lens implantation, were
retrospectively analyzed. The patients were divided into
two groups: I – 61 patients (71 eyes) with open angle
glaucoma, and II – 25 patients (29 eyes) with angle
closure glaucoma. Both groups were subdivided into two
subgroups, depending on presence of symptoms of
pseudoexfoliation (PEX) syndrome (A = with, and B =
without symptoms of PEX syndrome). All patients were
examined in the department where the surgeries were
performed; before surgery, on the first day after the
procedure, and again during the last follow-up
examinations, 6 to 30 months after the procedure.
Results: Before surgery, the intraocular pressure
(IOP) was at mean value of 19.02 ± 4.55 mmHg in group I,
and 20.01 ± 6.43 mmHg in group II. On the first day
after surgery, the IOP was 17.42 ± 7.17 and 20.36 ± 8.98
mmHg, respectively. IOP exceeding 20 mmHg was found in 7
eyes in group I, and in 6 eyes in group II. During the
last follow-up examinations the IOP was 14.59 ± 3.73 and
14.01 ± 4.50 mmHg, respectively, and was lower than
measured before surgery, by an average of 4.43 mmHg in
group I (P < 1 × 10-5), and 6.00 mmHg in group II (P < 1
× 10-4). In both groups, the reduction of IOP in
patients with PEX was even more remarkable. The number
of glaucoma medication necessary to control the pressure
was reduced on average by 0.28 in group I, and 0.31 in
group II.
Conclusions: Phacoemulsification done on
glaucomatous eyes results in lowering of IOP, and hence
the dosage of glaucoma drugs over the long term can be
simplified or even discontinued. |
| Słowa kluczowe: |
fakoemulsyfikacja, jaskra
otwartego kąta, jaskra zamkniętego kąta, zespół
pseudoeksfoliacji, ciśnienie wewnątrzgałkowe. |
| Key words: |
phacoemulsification, open
angle glaucoma, angle closure glaucoma,
pseudoexfoliation syndrome, intraocular pressure. |
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Patients with both advanced cataract and
glaucoma still pose a significant problem for the ophthalmic
surgeon. Depending on the severity of each disease, there exist
three treatment options for the affected patients. Either both
components of the surgical treatment (phacoemulsification of the
cataract and trabeculectomy) can be performed simultaneously (phacotrabeculectomy),
or these procedures can be done in two consecutive operations.
In people with high IOP and early-stage cataract, the
anti-glaucoma procedure is performed first, in order to
stabilize the pressure, and cataract extraction is done later.
More common, however, is the situation in which cataract
significantly impairs visual acuity, while pharmacological
therapy keeps the IOP below or only slightly above the target
value. In such cases, cataract phacoemulsification is performed
first, followed by antiglaucoma surgery if still necessary. The
reason for this sequence is that IOP is generally reduced
substantially after phacoemulsification or extracapsular
cataract extraction (ECCE) (1-7). This phenomenon occurs in most
cases – in patients with no glaucoma and patients with ocular
hypertension, as well as in glaucoma patients, although the
amount of IOP reduction varies in different situations. The
greatest reductions of IOP tend to occur in patients suffering
from angle closure glaucoma (ACG) (2). However, in patients with
open angle glaucoma (OAG), IOP reduction after cataract
extraction is also evident (2-4,8).
On the other hand, patients with glaucoma who underwent cataract
phacoemulsification first, often had temporarily elevated IOP
immediately after cataract extraction, and during the first days
afterwards (9). The magnitude and duration of these elevations
may result in irreversible glaucomatous effects.
Based on the above-mentioned information, we decided to analyze
a group of glaucoma patients who underwent cataract
phacoemulsification with intraocular lens implantation into the
capsular bag without any intraoperative anti-glaucoma procedure.
The objectives of our study were to evaluate the incidence and
magnitude of IOP elevations directly after surgery, and to
determine whether cataract phacoemulsification has long-term
effects on IOP level that may necessitate changes in glaucoma
treatment.
Patients and methods
A retrospective analysis was done on data from treatment of 100
eyes with glaucoma, on which phacoemulsification was performed
to remove cataracts that significantly impaired vision. Patients
with previous eyeball injuries, any ophthalmic surgeries, laser
treatment, or uveitis, as well as patients suffering from
congenital, juvenile, and secondary glaucoma, other than
pseudoexfoliative syndrome (PEX), were excluded from the study.
The patients were divided into two groups: those with open angle
glaucoma (OAG) comprised group I, and those with angle closure
glaucoma (ACG) were group II. The diagnosis of OAG was based on
gonioscopy, changes in visual field typical of glaucoma,
elevated IOP, and/ or characteristic changes in the appearance
of the optic nerve disc. The diagnosis of ACG involved the same
criteria, and additionally the history of acute angle closure
glaucoma.
In total, 86 patients (51 women and 35 men) underwent surgery.
The operations were on the right eye in 37 patients, the left
eye in 35, and both eyes in 14 patients. Group I included 71
eyes of 61 patients (34 women and 27 men). Pseudoexfoliation
syndrome (PEX) was found in 19 eyes in this group. These
patients were designated as subgroup I A. The 52 remaining eyes
with no PEX became subgroup I B. Surgery was performed on the
right eyes of 23 patients, the left eyes of 28 patients, and
both eyes of 10 patients in Group I. Group II was comprised of
29 eyes of 25 patients (17 women and 8 men). As with Group I,
Group II was divided into subgroups II A (4 eyes) and II B (25
eyes), depending on whether symptoms of PEX were present or
absent, respectively. Surgery on group II involved the right
eyes of 14 patients, the left eyes of 7, and both eyes in 4
patients.
To prepare each patient for surgery, we performed a full
ophthalmologic examination, supplemented by applanation
tonometry, gonioscopy, biometry, and intraocular lens (IOL)
power calculation. Every patient was checked for symptoms of PEX.
IOP was determined once again on the day of the operation. This
measurement was used as the baseline IOP in later statistical
analyses.
The same surgical protocol was used for all patients. As
premedication, 3.75 mg of midazolam (Dormicum, Roche) was orally
administered half an hour before the surgery. Surgery was
performed under topical anesthesia with proparacaine
hydrochloride (Alcaine, Alcon). The procedure consisted of
phacoemulsification of the cataract and implantation of the
acrylic IOL into the capsular bag through a clear corneal
incision. During capsulorhexis and IOL insertion, the anterior
chamber and capsular bag were filled with
hydroxypropylmethylcellulose 2% (Celoftal, Alcon). At the end of
surgery the viscoelastic material was carefully aspirated from
anterior and posterior chamber as well as from the space behind
the IOL. No peripheral iridectomy was made in any of the
procedures.
No complications occurred in 98 of the surgeries. In one patient,
rupture of the posterior capsule occurred, with vitreous
prolapse. Having performed anterior vitrectomy, a posterior
capsulorhexis was made, and a polymethyl-methacrylate (PMMA)
lens was inserted into the capsular bag. There were no further
postoperative complications in this case. In the other case, in
which a clear corneal incision was made, the wound leaked and
required one stitch. No other intraoperative complications
occurred.
On the day after the surgery, another full ophthalmic
examination was conducted, with special attention given to the
IOP values. Successive examinations were conducted by the
ophthalmologists who were treating the patients before the
surgery. For the final follow-up examination, the patients were
called after an average observation period of 15.9 months (6-30
months). The observation period averaged 15.3 months (6-30
months) for the patients from group I, and 17.4 months (6-28
months) for the patients in group II.
The pair wise statistical comparisons were made using two-tailed
Student’s t test. Statistical significance was defined as P ≤
0.05.
Results
The data regarding age of the patients, duration of glaucoma and
the number of glaucoma medications used before the cataract
phacoemulsification surgery are presented in Table I.
Table II lists the means, standard deviations, and ranges of IOP
values measured on the day of surgery, the first day afterwards,
and the day of the final follow-up examination.
Table II also summarizes the differences in IOP before and after
surgery, and their statistical significance. On the day after
surgery, the vast majority of patients had IOP ≤ 20 mmHg,
generally lower than immediately before surgery. However, the
differences in pre- and post-operative IOP were not
statistically significant for these patients.
Unfortunately, there were also patients whose post-operative IOP
increased, exceeding 20 mmHg. In Group I (the OAG group), there
were seven eyes, with post-operative IOP values of 25, 27, 29,
30, 32, 42 and 50 mmHg. In Group II (the ACG group),
post-operative IOP elevations occurred in 6 eyes, to 28, 29, 30,
37, 42 and 43 mmHg, respectively. Thus, post-operative IOP
elevations occurred in nearly 10% of the eyes in Group I, and
about 20% of the eyes in Group II. After topical administration
of 0.5% timolol maleate (Oftensin, Polfarma) and in some cases
oral acetazolamide (Diuramid, Polfarma) IOP in all of these eyes
quickly returned to normal.
During final follow-up examinations it was evident that most of
the eyes showed marked lowering of IOP in comparison to
pre-operative values. The post-operative vs. preoperative IOP
reductions were highly significant (P < 1 × 10-4) in Groups I A
and B (OAG with and without PEX), and Group II B (ACG without
PEX). The change was most pronounced in the A subgroups,
although Group II A (ACG with PEX), included only four eyes, and
thus could not provide significance statistics. The results are
summarized in Figure 1. In the last follow-up, IOP above 20 mmHg
were observed in only four patients: two from Group I (22 and 25
mmHg) and two from Group II (both 24 mmHg).
In almost one-fourth of the cases, the post-operative drop in
IOP was great enough to permit reduction in the types and
dosages of glaucoma medication needed to maintain IOP at a
steady, safe level. Four patients, however, required additional
drug therapy. These data are shown in tables III and IV.
Discussion
Small-incision phacoemulsification, followed by implantation of
a foldable intraocular lens, is currently a standard approach in
cataract treatment. The high effectiveness and low risk suggest
that there may be wider applications for this procedure. In
recent years it has been observed that the procedure also
results in a statistically and therapeutically significant drop
in IOP, in many patients without glaucoma (1,2,4,6,7), as well
as in patients with glaucoma (1-6,8). Thus, phacoemulsification
of cataract in an eye with glaucoma may be the method of choice
because, in addition to restoring visual acuity, it is likely to
have a beneficial effect on treatment of the glaucoma (2,4-6,8).
On the other hand, there is a well-documented risk that
phacoemulsification will cause transient IOP elevations
immediately after the cataract surgery (9-11). This risk applies
to all patients, regardless of the condition of their eyes
before the procedure. There are several possible causes of the
sudden IOP increases. Some published studies indicated that the
main cause is that the viscoelastic substance introduced during
surgery, is not completely removed from the anterior chamber.
Other potential causes of IOP spikes include inflammation caused
by the cortex remnants, blood cells, pigment particles, and free
radicals released during phacoemulsification (6,12,13). In
glaucomatous eyes, the additional factor contributing to IOP
spikes is obstruction of the routes for outflow of the aqueous
humor from the eyeball (6). Thus, such sudden IOP spikes may be
more frequent, and of larger amplitude in patients suffering
from glaucoma. This, in turn, may lead to irreversible visual
field changes.
In most of our patients, IOP measured in the first 24 hours
after surgery was lower than before the surgery. Unfortunately,
IOP spikes on the first day after surgery occurred in about 10%
of the group I patients and 20% of the group II patients. Such
IOP spikes directly after the procedure have been
well-documented (6,10). Shingelton, et al. (6) observed, as we
did, IOP spikes to levels as high as 44 mmHg in glaucoma
patients during the first 24 hours after phacoemulsification.
Despite the fact that IOP elevations of this type tend to
normalize when treated properly, they may still lead to
permanent changes. Therefore it is necessary to pay special
attention to intrasurgical preventive measures. These mainly
consist of very thorough removal of cortical masses and
viscoelastic agent from the eye (particularly when sodium
hyaluronate is used), and minimal contact of the surgical
instruments with the iris during phacoemulsification.
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We were particularly interested in
why the post-surgical IOP drop was so stable and long-lasting.
The IOP decrease as result of ECCE and cataract
phacoemulsification has been the subject of many studies (1-7).
However, it is hard to directly compare data in the literature,
because different authors investigated many different groups of
patients (for example, otherwise healthy, suspected glaucoma,
patients with OAG, ACG or secondary glaucoma due to PEX syndrome),
and observations were made over different time intervals. Among
OAG patients, IOP fell immediately after surgery, and remained
at near-normal levels from 12 months to 4 years following the
surgery. According to different sources, the drop in IOP was
1.4-1.9 mmHg (3), 1.55 mmHg (4), 1.88 mmHg (13), 2.9 mmHg (6),
3.1 mmHg (14), and 4.9-5.3 mmHg (2). Thus, the values recorded
in our study are within the upper limit of those in the
literature. The average IOP reduction amounted to 4.43 mmHg in
our OAG patients, and up to 6.00 mm Hg in our ACG patients.
Hayashi reported IOP reductions of 6.9 mmHg 12 months after the
procedure, and 7.2 mmHg at the two-year follow-up (2).
Merkur and his colleagues also presented interesting findings
(14). In their glaucoma patients with PEX, the average IOP
reductions after phacoemulsification were even greater (2.31
mmHg) than in OAG patients (1.88 mmHg). We also observed this in
our study: the reductions averaged 5.55- and 4.01 mmHg in our
OAG patients with, and without PEX, respectively, and 11.67- and
5.09 mmHg in our ACG patients with, and without PEX,
respectively.
For many of our patients, the IOP reductions allowed a decrease
in the number and/or dosage of antiglaucoma drugs (Table IV).
Similar findings were reported in studies already cited
(3,5,6,8). Hayashi, et al., observed IOP reductions large enough
that they were able to discontinue anti-glaucoma medication in
19.1% of their OAG patients, and 40.5% of their ACG patients
(2). Link, et al., were able to do the same for six of their 16
patients (4). Our outcome was similar. After surgery, six OAG
eyes and 3 ACG eyes in our cohort achieved target pressure
without glaucoma medication.
There is a plausible explanation for the large and long-lasting
IOP reduction in patients with ACG. ACG patients usually develop
enlargement and thickening of the lens. This leads to partial
pupillary block, narrowing of the iridocorneal angle, shallowing
of the anterior chamber, and eventually, to permanent impairment
of aqueous humor outflow through the angle. Extraction of the
altered lens restores the normal anatomic relations within the
anterior segment of the eye, deepening the anterior chamber,
widening the filtration angle, and allowing proper drainage of
the aqueous humor through the trabecular meshwork. This
hypothesis, supported by the results, suggests that early
cataract extraction would especially benefit patients with angle
closure glaucoma.
It is more difficult to postulate a mechanism for the
post-surgical IOP reductions in eyes with OAG. Three possible
mechanisms have been suggested in the literature: (a) a decrease
of aqueous humor production, (b) improved aqueous humor outflow
through the trabecular meshwork and Schlemm’s canal, and (c)
improved uveoscleral drainage. Hypothesis (a) seems unlikely,
because decreased aqueous humor production, even if it occurs
directly after the surgery, is only temporary. Mechanisms (b)
and (c) are more plausible ways of reducing the IOP. They are
consistent with results reported by Meyer, et al., who showed
that performing phacoemulsification on patients with suspected
glaucoma, increased the outflow rate of aqueous humor (12). The
most probable mechanism might be the increased prostaglandin
release. PGE1 increases the outflow through the conventional,
while PGF2α – through the alternative way. Improving of meshwork
drainage ability and conventional drainage way in primary
glaucoma eyes is less probable in an eye with primary glaucoma
due to permanent dysfunction of the outflow through this pathway
in an eye with simple glaucoma. Based on our measurements and
observations, in comparison with those of Altan, et al. (1), we
believe the most probable mechanism is (c); the improvement of
the drainage through the alternative (uveoscleral) pathway. We
are, however, still far from fully understanding long-term IOP
reduction in OAG.
It is somewhat easier to hypothesize how greater IOP reductions
occur in eyes with PEX syndrome. Others previously reported this
(14,15,16), and our observations confirm their findings.
Possibly the simplest hypothesis is that pseudoexfoliative
material is, at least in part, washed out from the anterior
chamber, particularly from the filtration angle, during
phacoemulsification. This would be expected to result in
increased outflow of aqueous humor through the trabecular
meshwork. Another contributing factor may be that the zonular
apparatus of the crystalline lens is very weak in some patients
with PEX syndrome. This could enable the whole lens to move
anteriorly, resulting in anterior chamber shallowing, and ACG.
In these patients, replacement of the crystalline lens with a
much thinner IOL implant should result in deepening of the
anterior chamber, alleviating symptoms of ACG. The combination
of washing out the pseudoexfoliative debris and deepening the
anterior chamber may act synergistically to lower the IOP. For
eyes with both cataract and glaucoma, our findings, and similar
data from other ophthalmology centers, show that cataract
extraction by phacoemulsification not only improves visual
acuity; it can also produce marked, long-term lowering of IOP.
In most of our patients, IOP remained unchanged, or fell
gradually, for several months after cataract extraction. This
simplified, and in some cases eliminated, glaucoma medication.
However, when glaucoma is difficult to control, and maintenance
of lower IOP is the first priority, cataract phacoemulsification
with intraocular lens implantation is not the only option. In
such cases trabeculectomy should be performed first, and
cataract extraction later, or alternatively the two surgeries
should be performed simultaneously. The benefit must be weighed
against the risk of transient IOP spikes immediately after the
phacoemulsification and IOL implantation. This risk can be
minimized by appropriate material and instrument handling, and
proper technique by a deft surgeon.
Conclusions
1. Performing phacoemulsification with intraocular lens
implantation on glaucomatous eyes, in most cases reduces IOP by
a few mmHg immediately after surgery. This reduction gradually
continues, or remains stable over periods of time extending to
years. In these instances, glaucoma therapy may be simplified,
or even discontinued.
2. IOP decreases are more evident in cases of angle closure
glaucoma and pseudoexfoliative glaucoma, than in cases of open
angle glaucoma.
3. The first day after the surgery, sudden IOP spikes can be
expected in some cases, and their occurrence will require a
conservative therapy.
References:
1. Altan C, Bayraktar S, Altan T, et al.: Anterior chamber depth,
iridocorneal angle width, and intraocular pressure changes after
uneventful phacoemulsification in eyes without glaucoma and with
open iridocorneal angles. J Cataract Refract Surg 2004, 30,
832-838.
2. Hayashi K, Hayashi H, Nakao F, Hayashi F: Effect of cataract
surgery on intraocular pressure in glaucoma patients. J Cataract
Refract Surg 2001, 27, 1779-1786.
3. Hudovernik M, Pahor D: Intraocular pressure after
phacoemulsification with posterior chamber lens implantation in
open-angle glaucoma. Klin Monatsbl Augenhkd 2003, 220, 835-839.
4. Link S, Haering G, Hedderich J: Einfluss der
Phakoemulsifikation und HKL-Implantation auf den
Intraokulardruck bei Patienten mit und ohne Offenwinkelglaukom.
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5. Mathalone N, Hyams M, Neiman S, et al.: Long-term intraocular
pressure control after clear corneal phacoemulsification in
glaucoma patients. J Cataract Refract Surg 2005, 31, 479-483.
6. Shingleton BJ, Gamel LS, O’Donoghue MW, et al.: Long-term
changes in intraocular pressure after clear corneal
phacoemulsification: normal patients versus glaucoma suspect and
glaucoma patients. J Cataract Refract Surg 1999, 25, 885-890.
7. Cekic O, Batman C, Totan Y: Changes in anterior chamber depth
and intraocular chamber pressure after phacoemulsification and
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8. Kim DD, Doyle JW, Smith MF: Intraocular pressure reduction
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9. Yasutani H, Hayashi K, Hayashi H, Hayashi F: Intraocular
pressure rise after phacoemulsification sutgery in glaucoma
patients. J Cataract Refract Surg 2004, 30, 1219-1224.
10. Boemer TG, Lagrze WDA, Funk J: Intraocular pressure rise
after phacoemulsification with posterior chamber lens
implantation: effect of prophylactic medication, wound closure
and surgeon’s experience. Br J Ophthalmol 1995, 79, 809-813.
11. Włodarczyk M, Wesołek-Czernik A, Synder A, et al.: Ciśnienie
śródgałkowe po fakoemulsyfikacji we wczesnym okresie
pooperacyjnym. (Intraocular pressure in early postoperative
period after cataract phacoemulsification). Klin Oczna 2004,
106, 194-195.
12. Meyer MA, Savin ML, Kopitas E: The effect of
phacoemulsification on aqueous outflow facility. Ophthalmology
1997, 104, 1221-1227.
13. Shingleton BJ, Waldhwani RA, O’Donoghue MW: Evaluation of
intraocular pressure in the immediate period after
phacoemulsification. J Cataract Refract Surg 2001, 27, 524-527.
14. Merkur A, Damji KF, Mintsioulis G, Hodge WG.: Intraocular
pressure decrease after phacoemulsification in patients with
pseudoexfoliation syndrome. J Cataract Refract Surg 2001, 27,
528-532.
15. Pohjalainen T, Vesti E, Uusitalo R J, Laatikainen L:
Phacoemulsification and intraocular lens implantation in open
angle glaucoma. Acta Ophthalmol Scand 2001, 79, 313-316.
16. Dosso AA, Bonvin ER, Leuenberger PM: Exfoliation syndrome
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122-125.
Neither author has a financial or proprietary interest
in any material or method mentioned.Praca
wpłynęła do Redakcji 30.04.2007 r. (996)
Zakwalifikowano do druku 12.12.2007 r.
Reprint requests to:
Andrzej Mierzejewski, MD
Department of Ophthalmology, Ludwik Rydygier’s Hospital
ul. Św. Jozefa 53/59
87-100 Torun, Poland
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