Zdrav Vestn Supl | The outcome of filtration surgery in  end-stage glaucoma I-29
IZVIrnI članek/OrIgInal arTIcle
The outcome of filtration surgery in  
end-stage glaucoma
rezultati filtracijske kirurgije pri glavkomu v končnem stadiju
Tomaž gračner, Dušica Pahor
Izvleček
Izhodišča: Ovrednotiti rezultate filtracijske ki-
rurgije pri glavkomu v končnem stadiju.
Metode: V to retrospektivno klinično raziskavo 
je bilo vključeno 20 oči 20 bolnikov z različnimi 
oblikami glavkoma v končnem stadiju. Pri vseh 
očeh je bil narejena goniotrepanacija s skleral-
nim poklopcem brez medoperativne uporabe 
antimetabolitov. Izmerjen je bil očesni tlak, ovre-
dnotena je bila najboljša korigirana vidna ostri-
na, število protiglavkomskih zdravil in rezultati 
testiranja vidnega polja pred in po kirurškem 
posegu.
Rezultati: Čas opazovanja po kirurškem posegu 
je bil pri vseh očeh 24 mesecev. Povprečni očesni 
tlak je bil pred kirurškim posegom 26,9 mmHg 
(SD 6,7) in 12,6 mmHg (SD 3,2) ob koncu opazo-
vanja, po kirurškem posegu nižji v celotnem času 
opazovanja (p< 0,0001). Povprečna najboljša ko-
rigirana vidna ostrina pred kirurškim posegom 
je bila 0,44 (SD 0,3), 3 mesece po kirurškem po-
segu 0,42 (SD 0,3) (p = 0.253) in 0,28 (SD 0,2) ob 
koncu opazovanja (p = 0,023). Povprečno število 
protiglavkomskih zdravil pred kirurškim pose-
gom je bilo 3,0 (SD 0,4), ki se je zmanjšalo na 
povprečno 0,3 (SD 0,9) ob koncu opazovanja po 
kirurškem posegu (p< 0,0001). Pred kirurškim 
posegom je bila povprečna vrednost povprečne 
deviacije pri 11 očeh na avtomatski perimetriji 
-27,49 dB (SD 2,1) in -27,73 dB (SD 1,6) po ki-
rurškem posegu (p = 0.289). Pred kirurškim po-
segom je bil povprečen otok vidnega polja pri 9 
očeh na Goldmannovi perimetriji 19,4° (SD 9,5) 
in 19,1° (SD 9,9) po kirurškem posegu (p = 0.347).
Zaključek: S filtracijsko kirurgijo pri glavkomu 
v končnem stadiju se je po 24 mesecih opazova-
nja značilno in stabilno znižal očesni tlak, vid pa 
je bil ohranjen brez nastanka t. i. pojava »wipe-
-out«.
Abstract
Background: To evaluate the outcome of filtra-
tion surgery in end-stage glaucoma.
Methods: This retrospective study included 20 
eyes of 20 patients with different forms of end-
stage glaucoma in which goniotrephining with 
scleral flap without intraoperative antimetabo-
lites was done. Intraocular pressure, best-cor-
rected visual acuity, number of antiglaucoma 
medications and visual field test results before 
and after surgery were evaluated.
Results: The follow-up after glaucoma surgery 
was 24 months in all eyes. The mean preoperative 
intraocular pressure was 26.9 mmHg (SD 6.7) 
and 12.6 mmHg (SD 3.2) at the end of follow-up; 
postoperatively it was lower at all follow-up vis-
its (p < 0.0001). The mean preoperative best-cor-
rected visual acuity was 0.44 (SD 0.3), 3 months 
postoperatively 0.42 (SD 0.3) (p = 0.253) and 0.28 
(SD 0.2) at the end of follow-up (p = 0.023). The 
mean number of antiglaucoma medications was 
3.0 (SD 0.4) preoperatively, decreasing postop-
eratively to a mean of 0.3 (SD 0.9) at the end of 
follow-up (p < 0.0001). Preoperatively, the mean 
value of the mean deviation in 11 eyes on au-
tomated perimetry was -27.49 dB (SD 2.1), and 
-27.73 dB (SD 1.6) postoperatively (p=0.289). 
Preoperatively, the mean visual field island in 9 
eyes on Goldmann perimetry was 19.4° (SD 9.5), 
and 19.1° (SD 9.9) postoperatively (p=0.347).
Conclusion: Filtration surgery in end-stage 
glaucoma followed for 24 months resulted in a 
significant and stable reduction of intraocular 
pressure and vision was preserved with no oc-
currences of »wipe-out« phenomenon.
Univezitetni klinični 
center Maribor, Oddelek 
za očesne bolezni, 
Ljubljanska 5,  
2000 Maribor, Slovenija
Korespondenca/
Correspondence:
doc. dr. Tomaž gračner, 
dr. med.
Univerzitetni klinični 
center Maribor, Oddelek 
za očesne bolezni
ljubljanska 5,  
2000 Maribor, Slovenija
Tel.: 00386–40–522765
e-mail: tomaz.gracner@
ukc-mb.si
Ključne besede:
filtracijska kirurgija, 
glavkom v končem 
stadiju, rezultati, očesni 
pritisk, vidno polje
Key words:
filtration surgery, 
end-stage glaucoma, 
outcome, intraocular 
pressure, visual field
Citirajte kot/Cite as:
Zdrav Vestn 2012;  
81: I-29–36
Prispelo: 20. dec. 2011, 
Sprejeto: 4. apr. 2012
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End-stage glaucoma was defined on the 
basis of VF examination. The VF was exa-
mined by either automated static perimet-
ry (Swedish Interactive Threshold Algori-
thm [SITA] standard 30–2 program of the 
Humphrey Field Analyser) or kinetic peri-
metry (Goldmann perimetry), depending 
on the patient’s capability to respond at the 
field examination. All patients had advanced 
glaucomatous VF loss with mean deviation 
> -12 dB according to the Hodapp classifica-
tion on automated perimetry, or an extensi-
ve ring-shaped or half-ring-shaped absolute 
defect in the paracentral VF area with a cen-
tral island stage IV according to the Aulhorn 
classification on Goldmann perimetry.9,10
Indications for filtration surgery inclu-
ded end-stage glaucoma with a cup-disc ra-
tio (C/D) of 1.0 and severe VF defects with 
partially preserved central function and 
insufficient control of intraocular pressure 
(IOP) including causes such as allergies, low 
compliance and high number of antiglauco-
ma medications.
All patients were operated on by an expe-
rienced surgeon (T.G.), using local anesthe-
sia after peribulbar injection of mixtures 
of lidocaine hydrochloride 2 % (Xylocain-
eâ) and bupivacaine hydrochloride 0.75 % 
(Marcaine). The surgical technique – supe-
rior goniotrephining with a scleral flap wi-
thout intraoperative antimetabolites – was 
the same in all eyes.11 A fornix-based co-
njunctival flap was created, incising the co-
njunctiva and Tenon’s capsule at the limbus 
at the 12 o’clock position. A 5 mm x 4 mm 
half-thickness scleral flap was dissected un-
til the clear cornea was reached. The gonio-
trephination was carried out with a rotating 
trephine with a diameter of 1.5 mm and fol-
lowed by peripheral iridectomy. The scleral 
flap was closed with two 8.0 Vicryl sutures 
tied in a way that allowed guarded filtration 
of aqueous humor. At the end of the operati-
on the conjunctiva was closed using separate 
8.0 Vicryl sutures. At the end of the surgical 
procedure, 4 mg of dexamethasone was ap-
plied subconjunctivally to all eyes. The usual 
postoperative treatment included: cyclople-
gic eye drops (1 % atropine) once a day for 
one week; a combination of dexamethasone, 
neomycin and polymyxin B (Maxitrol) eye 
Introduction
There is controversy about the outcome 
of filtration surgery in end-stage glaucoma. 
By a number of investigators it has been re-
ported that filtration surgery in end-stage 
glaucoma may be associated with the risk 
of immediate unexplained postoperative 
visual field (VF) loss, which includes fixati-
on with an accompanying change in central 
visual acuity, termed »wipe-out« phenome-
non.1-4 There are conflicting reports about 
the frequency of »wipe-out« phenomenon 
which results in a decreased quality of life 
for glaucomatous patients. So, some state 
the rate of severe loss of central vision after 
filtration surgery as high as 7.7 %, whereas 
others regard this phenomenon as extreme-
ly rare.1-8
The purpose of this clinical study was to 
evaluate the outcome of filtration surgery in 
end-stage glaucoma during the immediate 
and mid-term postoperative period.
Patients and methods
In this retrospective clinical study we 
included all patients from the glaucoma 
unit of the Department of Ophthalmology 
of the University Medical Centre Maribor, 
Maribor, Slovenia, who had different forms 
of end-stage glaucoma with a cup-disc ratio 
(C/D) of 1.0 and severe VF defects with par-
tially preserved central function, in whom 
filtration surgery was performed between 
January 2002 and December 2007.
All preoperative, operative and posto-
perative medical data were acquired from 
accessible medical documentation. The pati-
ents were informed of the risks, benefits and 
alternatives of surgery, and their informed 
consent was obtained.
The data recorded preoperatively inclu-
ded diagnosis, age, gender, ocular history, 
duration of glaucoma medical treatment, 
number of antiglaucoma medications, best-
-corrected visual acuity (BCVA) (decimal 
equivalents of Snellens visual acuity), slit 
lamp examination, Goldmann applanation 
tonometry, fundus evaluation and perimet-
ry.
Zdrav Vestn Supl | The outcome of filtration surgery in  end-stage glaucoma I-31
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last follow-up visit after surgery were used 
for comparison.
Student’s t-test for paired data and the 
chi-squared test were used for statistical 
analysis of the results. Significant P values 
were considered to be less than 0.05.
Results
Twenty eyes of 20 patients were inclu-
ded in this retrospective clinical study. There 
were 12 men (60 %) and 8 women (40 %) and 
their mean age was 70.7 years (SD 5.7), with 
a range of 61–83 years. The most frequent 
diagnosis was pseudoexfoliation glaucoma 
found in 12 eyes (60 %), 6 eyes (30 %) had 
primary open-angle glaucoma and 2 eyes 
(10 %) had chronic angle-closure glaucoma. 
drops five or six times a day for 2 weeks, then 
four times a day for 2 weeks, then three ti-
mes a day for 3 weeks, then twice a week for 
3 weeks, then once a day for 2 weeks, altoge-
ther for the duration of 12 weeks. Intraope-
rative and postoperative complications and 
their management were noted.
The data recorded postoperatively in-
cluded slit lamp examination, Goldmann 
applanation tonometry, BCVA, number of 
antiglaucoma medications, fundus evalu-
ation and perimetry. The IOP was measu-
red for one week, at one, 3, 6, 12, 18 and 24 
months after surgery. The BCVA and the 
number of antiglaucoma medications were 
evaluated 3 months after surgery and at the 
end of follow-up. The VF test results within 
6 months before and 6 months before the 
Table 1: Baseline characteristics.
Patient Gender Age (years) Eye Glaucoma Type
1 F 62 OD PeX
2 F 76 OD POag
3 M 61 OD PeX
4 F 72 OD PeX
5 M 70 OS POag
6 M 76 OD PeX
7 F 71 OS PeX
8 F 67 OD POag
9 M 83 OS cag
10 M 63 OD POag
11 F 79 OS POag
12 M 76 OD cag
13 F 68 OD PeX
14 M 69 OS PeX
15 M 76 OS PeX
16 M 68 OD PeX
17 M 70 OD PeX
18 F 67 OS POag
19 M 70 OS PeX
20 M 71 OD PeX
PEX – Pseudoexfoliation glaucoma
POAG – Primary open-angle glaucoma
CAG – Chronic angle closure glaucoma
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months after filtration surgery was statisti-
cally nonsignificant (P = 0.253). At the last 
postoperative follow-up visit, a cataract 
with a decrease of BCVA was noted in 4 
eyes (20 %). At the last postoperative follow-
-up visit the mean BCVA was 0.28 (SD 0.2), 
with a range of 0.01–0.8. The difference bet-
ween the mean preoperative BCVA and the 
mean BCVA after filtration surgery at the 
end of follow-up was statistically significant 
(P = 0.023).
The mean number of antiglaucoma me-
dications 3 months after filtration surgery 
was 0.25 (SD 0.8), with a range of 0–3. At the 
last postoperative follow-up visit the mean 
number of antiglaucoma medications was 
0.3 (SD 0.9), with a range of 0–3. The dif-
ference between the mean number of anti-
glaucoma medications before filtration sur-
gery and the mean number of antiglaucoma 
medications after filtration surgery at the 
end of follow-up was statistically significant 
(P < 0.0001). In 2 eyes (10 %) antiglaucoma 
medications had to be added during the fol-
low-up after filtration surgery because of an 
insufficient reduction of IOP (in one eye two 
antiglaucoma medications after 3 months 
and then another one after 6 months; in 
one eye three antiglaucoma medications 3 
months after surgery).
Postoperatively, the mean value of MD 
was -27.73 dB (SD 1.6) on automated peri-
metry. The difference between the mean 
preoperative MD and the mean MD after 
filtration surgery was statistically nonsigni-
ficant (P = 0.289). Postoperatively, the mean 
VF island was 19.1° (SD 9.9) on Goldmann 
perimetry. The difference between the mean 
preoperative VF island and the mean VF 
island after filtration surgery was statistical-
ly nonsignificant (P = 0.347).
IOP, BCVA, number of antiglaucoma 
medications and visual field test results be-
fore and after filtration surgery in the cohort 
of 20 patients with end-stage glaucoma are 
listed in Table 2.
Discussion
Large clinical trials have clearly shown 
that successful lowering of IOP is associated 
with a decrease in VF progression.12-15 Pa-
The baseline characteristics are listed in Ta-
ble 1.
All eyes were phakic without demon-
stration of previous ocular trauma, uveitis 
or ocular surgery, except for laser trabecu-
loplasty or laser iridotomy. Before filtration 
surgery, a selective laser trabeculoplasty was 
done in one eye (5 %) and a peripheral laser 
iridotomy was done in one eye (5 %).
The mean duration of glaucoma medical 
treatment before filtration surgery was 3.0 
years (SD 2.8), with a range of 0.5–10 years.
The mean number of antiglaucoma me-
dications before filtration surgery was 3.0 
(SD 0.4), with a range of 2–4.
The mean preoperative BCVA was 0.44 
(SD 0.3), with a range of 0.01–1.0.
The VF was examined by threshold au-
tomated perimetry in 11 eyes (55 %) and by 
Goldmann perimetry in 9 eyes (45 %). Pre-
operatively, the mean value of the mean de-
viation (MD) was -27.49 dB (SD 2.1) on au-
tomated perimetry. Preoperatively the mean 
VF island was 19.4° (SD 9.5) on Goldmann 
perimetry.
The mean IOP before filtration surgery 
was 26.9 mmHg (SD 6.7), with a range of 
17–43 mmHg.
No intraoperative complications such as 
anterior chamber hyphema or others were 
noted.
Postoperatively, transient hypotony with 
flat anterior chamber and choroidal deta-
chment was noted in 10 eyes (50 %) and re-
solved in all eyes within 7 days.
The follow-up period after filtration sur-
gery was 24 months in all eyes.
The mean IOP one week after filtrati-
on surgery was 7.5 mmHg (SD 2.3), at one 
month postoperatively 12.7 mmHg (SD 3.7), 
at 3 months 11.5 mmHg (SD 3.4), at 6 months 
11.9 mmHg (SD 3.3), at 12 months 12.5 mmHg 
(SD 3.0), at 18 months 12.4 mmHg (SD 3.3), 
and at the end of 24 months of follow-up 
12.6 mmHg (SD 3.2). At all follow-up visits 
after filtration surgery the mean IOP was 
statistically lower than the mean IOP before 
surgery (P < 0.0001).
The mean BCVA 3 months after filtration 
surgery was 0.42 (SD 0.3), with a range of 
0.01–0.9. The difference between the mean 
preoperative BCVA and the mean BCVA 3 
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mend filtration surgery because of concerns 
about the possibility of the occurrence of 
»wipe-out« phenomenon. In the published 
studies the rate of the occurrence of »wipe-
-out« phenomenon is controversially evalu-
ated and discussed.1-8
Although the exact mechanism of the 
»wipe-out« phenomenon remains elusive, it 
has been suggested that it may be associated 
with the occurrence of sudden, intraopera-
tive ocular hypotony during glaucoma sur-
gery. This may result in optic nerve hemor-
tients with end-stage glaucoma with a cup-
-disc ratio (C/D) of 1.0 and severe VF defec-
ts with partially preserved central function 
and insufficient control of IOP are at high 
risk of further disease progression, which 
may affect the central vision. A reduction or 
stabilization of IOP can be achieved either 
with medication or by surgery. It has been 
shown that the IOP could be reduced more 
effectively with filtration surgery than with 
medication.14 In patients with end-stage gla-
ucoma surgeons may be hesitant to recom-
Table 2: Intraocular pressure, best-corrected visual acuity, number of antiglaucoma medications and visual field test results before 
and after filtration surgery in the cohort of 20 patients with end-stage glaucoma.
Patient
IOP
(mmHg)
Entry
IOP
(mmHg)
Exit
BCVA
Entry
BCVA
Exit
No.GM
Entry
No.GM
Exit
AP
(MD)
Entry
AP
(MD)
Exit
GP
( °)
Entry
GP
(°)
Exit
1 23 10 0.16 0.16 3 0 -28.77 -28.99 / /
2 23 15 0.2 0.2 3 0 / / 30 30
3 30 17 0.01 0.01 3 0 / / 20 20
4 30 8 0.1 0.1 3 0 -26.55 -26.88 / /
5 26 12 0.5 0.4 4 0 -27.50 -27.85 / /
6 22 10 0.8 0.2 3 0 -29.92 -29.27 / /
7 34 8 0.7 0.7 3 0 -25.50 -27.24 / /
8 17 10 0.1 0.05 3 0 / / 30 30
9 24 14 0.1 0.16 4 0 / / 20 20
10 26 14 1.0 0.8 3 3 -25.23 -26.00 / /
11 18 11 1.0 0.1 3 0 / / 10 7
12 28 20 0.4 0.2 3 3 / / 20 20
13 27 14 0.7 0.7 3 0 / / 30 30
14 35 10 0.2 0.2 3 0 / / 10 10
15 27 12 0.3 0.4 3 0 -30.86 -30.02 / /
16 28 16 1.0 0.2 3 0 -26.30 -26.50 / /
17 43 14 0.6 0.2 3 0 -25.84 -26.54 / /
18 17 12 0.4 0.4 3 0 -30.36 -30.03 / /
19 24 10 0.01 0.01 2 0 / / 5 5
20 37 14 0.6 0.5 3 0 -25.57 -25.72 / /
IOP – Intraocular pressure
BCVA – Best-corrected visual acuity (decimal equivalents of Snellens visual acuity)
No.GM – Number of antiglaucoma medications
AP – Automated perimetry
MD – Mean deviation (dB)
GP – Goldmann perimetry
°–Degrees
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regard to patients with advanced VF defects 
and preoperative preserved foveal fixation. 
They concluded that a loss of the central VF 
and central fixation immediately after filte-
ring surgery is a rare complication.4
In their prospective study, which included 
21 eyes with end-stage glaucoma, Topouzis 
et al. evaluated the effect of trabeculectomy 
with mitomycin-C during the immediate 
postoperative period.8 The VF was exami-
ned by automated perimetry. They conclu-
ded that in their study filtration surgery in 
end-stage glaucoma followed for 3 months 
resulted in an effectively reduced IOP and 
vision was preserved with no occurrences of 
»wipe-out« phenomenon.8
Awai et al., in their retrospective study, 
which included 49 eyes with end-stage glau-
coma, evaluated the effect of trabeculectomy 
with mitomycin-C and postoperative laser 
suture lysis during the immediate posto-
perative period.5 The VF was examined by 
Goldmann perimetry. They concluded that 
in their study filtration surgery in end-stage 
glaucoma followed for 2 months resulted in 
an effectively reduced IOP. Also, postope-
ratively no loss of foveal fixation or loss of 
central visual acuity was found, and thus no 
occurrence of »wipe-out« phenomenon was 
noted.5
In their retrospective study, which in-
cluded 117 eyes with severe VF defects, Law 
et al. evaluated the effect of trabeculectomy 
with mitomycin-C during the immediate 
postoperative period.6 The VF was exami-
ned by automated perimetry. In 7 eyes (6 %) 
they reported a postoperative central vision 
loss, which was the consequence of hypoto-
nic maculopathy in 3 eyes, of uncontrolled 
elevated IOP in 2 eyes, of posterior subcap-
sular cataract in one eye, and the consequen-
ce of inflammatory reaction in one eye. Po-
stoperatively, no loss of central visual acuity 
or loss of central VF was found that could 
not be explained by morphological changes 
on the posterior pole of the eye, and thus no 
occurrence of »wipe-out« phenomenon was 
found.6
In our retrospective study, which inclu-
ded 20 eyes with end-stage glaucoma, we 
evaluated the outcome of goniotrephining 
with scleral flap without intraoperative an-
rhage and decreased perfusion pressure to 
an already compromised optic nerve blood 
supply. It may also include a microembolic 
episode that could damage the remaining 
fiers.7,8
In their prospective study, which in-
cluded 26 eyes with end-stage glaucoma, 
Aggarwal and Hendels evaluated the effect 
of trabeculectomy without the use of anti-
metabolites during the immediate posto-
perative period.1 The VF was examined by 
Goldmann perimetry. They reported a po-
stoperative loss of central visual acuity in 
4 eyes (15.4 %). In one eye it was the con-
sequence of a macular edema and in one eye 
of a flat anterior chamber. In 2 eyes (7.7 %) 
they could not find any explainable reason 
for the loss of foveal fixation and a decrease 
in visual acuity. They concluded that there 
was a considerable risk for the occurrence of 
»wipe-out« phenomenon after filtration sur-
gery in eyes with end-stage glaucoma.1
In their retrospective study, which inclu-
ded 508 eyes with different stages of glauco-
matous optic neuropathy, Costa et al. eva-
luated the effect of trabeculectomy during 
the immediate postoperative period.2 The 
VF was examined by either automated pe-
rimetry or Goldmann perimetry. In only 4 
eyes (0.95 %) they reported a postoperative 
loss of foveal fixation and central VF loss 
that occurred within 3 months after surgery, 
without any morphological changes on the 
posterior pole of the eye, which could be a 
reason for the central vision loss. They con-
cluded that a »wipe-out« phenomenon after 
filtration surgery in eyes with end-stage gla-
ucoma is a very rare phenomenon, but it can 
occur.2
Thiel et al., in their retrospective study 
which included 408 eyes with advanced VF 
loss, evaluated the effect of goniotrephining 
with a scleral flap without intraoperative 
antimetabolites.4 The VF was examined by 
either Tübinger automated perimetry or Tü-
binger hand-perimetry. They evaluated the 
prevalence of the loss of visual acuity due 
to loss of the central portion of the VF and 
foveal fixation in the first week after glauco-
ma filtering surgery. The incidence of such a 
complication in their study was 0.5 % with 
regard to all operated patients and 1.4 % with 
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IZVIrnI članek/OrIgInal arTIcle
selected subpopulations within the same 
outcome study. Despite the limitations, me-
aningful information can be derived from 
outcome studies. The results of our study 
provided information about the outcome 
of filtration surgery in end-stage glaucoma 
during the immediate and mid-term posto-
perative period that resulted in a significant 
and stable reduction of IOP and vision was 
preserved with no occurrences of »wipe-
-out« phenomenon.
On the basis of the results of our own 
and other studies we can conclude that a 
»wipe-out« phenomenon after filtration su-
rgery in end-stage glaucoma represents a 
very rare complication. Therefore, end-stage 
glaucoma should not be a contraindication 
for filtration surgery.
timetabolites during the immediate and 
mid-term postoperative period. The VF was 
examined by either automated perimetry or 
Goldmann perimetry. During the immedia-
te postoperative period, 3 months after filte-
ring surgery, we found a significant reducti-
on of IOP, a stable VF and stable BCVA. The 
postoperative transient hypotony with flat 
anterior chamber and choroidal detachment 
in half of the operated eyes was the con-
sequence of overfiltration and may be pre-
vented by the use of adjustable or releasable 
sutures at the time of surgery. During the 
mid-term postoperative period we found a 
significant and stable reduction of IOP and 
a significant decrease in the number of an-
tiglaucoma medications. The statistically si-
gnificant difference between the mean preo-
perative BCVA and the mean postoperative 
BCVA at the end of follow-up, 24 months 
after filtration surgery can be explained as a 
consequence of the occurrence of a cataract, 
which was observed in 4 eyes (20 %). So, in 
our study after filtration surgery in end-sta-
ge glaucoma during the immediate and mid-
-term postoperative period no occurrence 
of »wipe-out« phenomenon was observed.
Because of the differences in glaucoma 
forms, age, gender, previous ocular history, 
duration of glaucoma medical treatment, 
type of antiglaucoma medications, amount 
of glaucomatous optic neuropathy, type of 
VF examination, grade of VF deterioration, 
operative technique, number of included 
eyes, follow-up time, study design, evalua-
tion and statistical analysis of the results of 
included patients, a comparison of the men-
tioned studies is very difficult and its pos-
sibility limited. The result of our study of a 
significant reduction of IOP and no occur-
rence of »wipe-out« phenomenon during 
the immediate postoperative period after 
filtration surgery in end-stage glaucoma are 
consistent with the results of studies perfor-
med by Topouzis et al., Awai et al. and Law 
et al.8,5,6
There are limitations of interpreting re-
sults from outcome studies. There is no con-
trol group in such a study. Surgical outcome 
studies allow the comparison of individual 
or group practitioner results with other pu-
blished historical surgical reports or with 
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9. Hodapp E, Parrish IIRK, Anderson DR: Clinical 
decision in glaucoma. St Louis, CV Mosby Comp 
1993; 52–61.
10. Aulhorn E, Karmeyer H: Frequency distribution 
in early glaucomatous visual field defects. Doc 
Ophthalmol 1977; 14: 75–83.
11. Fronimopoulos J: Die Goniotrepanation mit Skle-
radeckel in der heutigen Chirurgie des Glaukoms. 
Klin Monatsbl Augenheilkd 1981; 178: 159–70.
12. Collaborative Normal-Tension Glaucoma Study 
Group: Comparison of glaucomatous progression 
between untreated patients with normal-tension 
glaucoma and patients with therapeutically redu-
ced intraocular pressures. Am J Ophthalmol 1998; 
126: 487–97.
13. Heijl A, Leske MC, Bengtsson B, et al: Early Mani-
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