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A retrospective and consecutive study of viscocanalostomy
versus trabeculectomy
for primary congenital glaucoma
ABSTRACT:
Background
To compare the efficacy and safety of viscocanalostomy and MMC-trabeculectomy
in patients with primary congenital glaucoma.
Methods
Consecutively 43 patients with primary congenital glaucoma who underwent either
viscocanalostomy (group 1) or MMC-trabeculectomy (group 2) between June 2003 and June 2008
were retrospectively reviewed. The patients’ intraocular pressures (IOPs) were examined before
surgery and on day1,week1,month1, month 6 and month 12. Mean horizontal corneal diameter,
success rates, intra-and postoperative complications were compared between two groups.
Results
Mean preoperative IOP was 31.96(SD3.9) mmHg in group1 and 32.56(4.0) mmHg in
group 2. At the last visits, it was 16.78(2.2) mmHg and 15.77(2.6) mmHg ,respectively (P<0.001). At
the last visit, the complete success rates of group1 and group2 were 45.9% and 67.4%, respectively,
and the difference was not statistically significant (P=0.158).There was no major complications
occurred in the two groups.
Conclusions
Both viscocanalostomy and trabeculectomy can lowered IOP in primary congenital
glaucoma patients effectively. Although there was no major complications occurred in both groups,
viscocanlostomy may decrease the probability of postoperative haemorrhage, hypotony, cataract or
choroid effusion.
Key words: primary congenital glaucoma; viscocanalostomy; trabeculectomy
1
INTRODUCTION
Primary congenital glaucoma (PCG) due to isolated trabeculodysgenesis is the commonest
glaucoma seen in infancy which accounts for 0.01–0.04% of total blindness 1. As a globle problem ,
PCG poses a diagnostic and therapeutic challenge to the ophthalmologist not only in the western
countries2,3, but also in China4. Only early recognition and treatment can help physicians in
preserving sight for these young patients5.
Surgical interventions are the main treatment for PCG6 and are designed restore the aqueous
humor pathway and to lower elevated IOP7. The strategy of pressure reducing surgery in primary
congenital glaucoma has changed over the last decade. Goniotomy and trabeculotomy have
traditionally been regarded as procedures of choice for PCG because of high reported success
rates8,9. Trabeculectomy is the operation of choice in PCG cases in whom angle surgery has failed,
or when a very low target pressure is required due to advanced disease. Several studies have
shown that mitomycin C(MMC)-augmented trabeculectomy is an effective surgical method for PCG,
but was also associated with a higher incidence of complications 10-15. Moreover, some reports have
found combined trabeculotomy–trabeculectomy
to yield superior results in comparison with
conventional procedures16-19.
Viscocanalostomy is a non-penetrating surgery that was described by Stegmann and coauthors in
the 1990s20. The procedure is a deep sclerectomy with viscoelastic dilation and unroofing of
Schlemm’s canal and is mostly used in the primary open angle glaucomas(POAGs)21-24. Recent
studies showed that the non-penetrating techniques and viscocanalostomy could also been carried
2
out in PCGs25,26.
In China, majority of children with PCG present with severe disease and cloudy cornea 4.
Conventional trabeculectomy has been the surgical method commonly used for PCG treatment in
China, but several postoperative complications such as potentially blinding bleb-related infections
are also reported27,28. A more safety and higher long-term success rate primary surgical procedure
will therefore be of great benefit to these children.
The purpose of this study was to evaluate the outcomes of viscanalostomy and MMC-augmented
trabeculectomy, and to compare these two techniques in PCG treatment.
PATIENTS AND METHODS
Patient Selection
The charts of 43 patients with primary congenital glaucoma who underwent either viscocanalostomy
(group 1) or MMC-augmented trabeculectomy (group 2) between June 2003 and June 2008 were
retrospectively reviewed. All patients had at least 1 years of follow-up. Each patient’s legal
representative received a comprehensive explanation about the two surgeries, its implications and
signed a written informed consent before surgery. Selection of the technique to be used in this
series was determined by the preference of the patient’s representatives.
Group 1 consisted of 27 eyes of 18 patients who had undergone viscocanalostomy, and group 2
consisted of 39 eyes of 25 patients who had undergone MMC-augmented trabeculectomy. Patients
3
with a history of previous surgery, with secondary glaucoma, with Axenfeld–Rieger syndrome or
aniridia or Sturge–Weber syndrome were excluded from study.
Data Recorded
An examination under ketamine anesthesia was performed in all cases. PCG was defined by
elevated IOP, enlarged corneal diameter and/or cornea cloudiness, Descemet tears or Haab’s striae,
and/or abnormal anterior chamber findings under gonioscopy, as assessed by an experienced
glaucoma specialist(YZL). Age, sex, family history, main presenting features, antiglaucoma
medications, time of surgery, follow-up time, intra- and postoperative complications and success
rates were all recorded. Pre- and postoperative examinations included measurement of IOP,
determination of horizontal corneal diameters. IOP measurements were assessed using TONO-Pen
AVIA (Reichert, NY).
Operative Procedures
All operations were performed by 1 experienced ophthalmic surgeon (YZL) under general
anesthesia. MMC-augmented trabeculectomy was performed using a standardised technique
similar to that described by Rodrigues14. Briefly, a fornix-based conjunctival flap was made and a
rectangular 4×5 mm scleral flap was created and dissected forward into cornea because of limbal
distension in buphthalmic eyes. MMC was applied at 0.02 mg/mL for 3 minutes. A 2×2 mm inner
trabeculectomy groove was carried out and was excised with Vannas scissors and peripheral
iridectomy was performed with a base of at least 2mm. The partial thickness scleral flap was
sutured using two interrupted sutures with 10–0 nylon. The conjunctival flap was closed with 8–0
4
vicryl (polyglactin) continuous stitches.
In viscocanalostomy, the technique consisted in a fornix based conjunctiva opening, followed by the
creation of a tongue-shaped superficial scleral flap measuring 5×4 mm, one third of the full sclera
thickness and dissected 1.0mm into clear cornea. A deep scleral flap measuring 4×3 mm, leaving
only a very thin layer of sclera with a barely visible choroidal underneath, was then dissected down
to the Schlemm’s canal and gently cut at the level of the trabeculo-Descemet membrane.
High-viscosity sodium hyaluronate (Healon GV®, Pfizer) was injected into the Schlemm canal to
further dilate and maintain patency of the canal at each ostium. The internal wall of Schlemm’s
canal along with juxtacanalicular connective tissue was peeled away carefully with the blunt end of
a 20G needle. The outer scleral flap was closed with three to four interrupted 10-0 nylon sutures.
The viscoelastic was injected beneath the flap and into a “scleral lake” that was created in the
absence of the inner flap. The conjunctival and Tenon’s tissue were closed with an 8-0 Vicryl
running suture（Figure 1 A-I）.
A dexamethasone/tobramycin (TobraDex; Alcon, Inc.) ointment were given at the conclusion of the
case. Postoperative treatment consisted of topical application of tobramycin and dexamethasone 5
times per day for 1month.
Criteria for Success
Complete surgical success was determined by an IOP<18 mmHg under general anaesthesia
without medication or resurgery, with no progression corneal diameter. Failure was defined as IOP
≥18 mmHg in patients with medication, resurgery or sight-threatening complications29.
5
Postoperative Follow-up
Intraocular pressure and complications were recorded preoperatively on 2 separate days, at
postoperative days 1 and 7, months 1, 2, 6, and 12. Horizontal corneal diameters were measured
before surgery and at 6 months postoperativly.
Any complication was recorded and was defined as either a major or minor complication based on
the clinical significance and importance over time. Evaluation of the complications was based on the
surgeon’s clinical experience. Minor complications were hyphema, shallow anterior chamber, and
choroidal detachment. Hyphema was present when blood collection was seen in the anterior
chamber. Anterior chamber depth was clinically assessed under slit-lamp examination and was
considered shallow when iridocorneal touch in the periphery was noticed. Choroidal detachment
was observed under indirect ophthalmoscopy. All these complications were considered minor
because they either resolved spontaneously or required minimal medical treatments. The major
complications were endophthalmitis, total choroidal detachment or phthisis bulbi.
Statistical Analysis
Data are expressed as mean values±standard deviation (SD), and were analysed statistically by
using the Student t test, two-way ANOVA. A P value<0.05 was considered statistically significant.
Long-term success of IOP control was estimated by the Kaplan–Meier life-table method. The
statistical analysis was performed using GraphPad Prism 5 Demo.
RESULTS
Patient Demographics
6
The characteristics of the patients are listed in table1. A total of 63 eyes of 43 PCG patients were
enrolled in our study. All patients were systemically normal, had no other ocular abnormalities, and
were treated surgically as the primary treatment. Age of time of first surgical was 13.31(7.8) months
in group 1 and 14.86(8.3) months in group 2.The age of surgery had no significant difference between
two groups (P=0.537) (Figure 2).
Intraocular Pressure
Figure 3 shows the mean (SD) IOP at different visits in either group of eyes. The mean (SD)
preoperative IOP of viscocanlostomy eyes was 31.96(3.9) mmHg , whereas that of trabeculectomy
eyes was 32.56(4.0) mmHg. At day 1, week1, month1, mongth 6 and mongth12 after surgery , the
mean IOPs were 11.22(2.5) mmHg, 12.85(2.4) mmHg, 14.67(2.5) mmHg, 16.44(3.2) mmHg and
16.78(2.2) mmHg , respectively in group 1. At each follow-up time point ,the IOPs in group 2 were
10.44(3.8) mmHg,12.13(2.5) mmHg,13.72(2.8) mmHg,15.44(2.7) mmHg and 15.77(2.6) mmHg,
respectively (Figure 3). Statistical analysis showed no significant difference in IOP measurements
between the study groups at each follow-up visit, P>0.1 (Figure 4). However, the decrease in IOP in
each of the two groups was significant at every follow-up time point, P<0.01(Table 2).
Cornea Parameters
Along with the IOP decreasing, we found a significant decrease in the postoperative horizontal
corneal diameters (12.73(0.6) mm) in group 1 when compared with preoperative ones (13.43(0.7)
mm), P<0.001. Similar findings were observed when we compared the group 2 postoperative
horizontal corneal diameters (12.39(0.7) mm) with the preoperative ones (13.43(1.0) mm),
7
P<0.001(Figure 5).
Success Rate
Figure 6 shows the complete success rate in both groups based on the Kaplan-Meier cumulative
survival curve. At the end of the follow-up, the surgical success in grouop 1 was 45.9%, while that of
group 2 was 67.4%. The difference between the viscocanalostomy group and the trabeculectomy
group was not statistically significant at any time during the follow-up (P>0.1).In group 1, 4 eyes out
of 27 were classified as a failure owing to the need for further surgery. While in group 2, IOP of 5
eyes couldn’t controlled with further antiglaucoma medications lead to second surgery.
Complications
The surgical procedure was performed without serious intraoperative or postoperative complica
-tions. Blood refuxed into the anterior chamber at the time of surgery only happened in 1 eye and 3
eyes in group 1 and 2 respectively, but fewer hyphema was seen postoperatively. Postoperative
complications were listed in Table 3. Transient early hypotony (IOP≤5 mmHg) and cataract
formation occurred more often in group 2. But there was no statistical difference between the two
groups (P>0.1). The most common complication in group 2 was transient hypotony (6/39, 15.4%)
which could self relieved without additional treatment. Only a few of them were treated with topical
dexamethasone eyedrops frequently. Descement’s membrane detachment occurred in 2 patients in
group 1. No patient exhibited flat anterior chamber, early or late postoperative infection.
DISCUSSION
8
Primary developmental glaucoma results from the structural maldevelopment of the aqueous
outflow system. There are mainly four kinds of structural maldevelopment : goniodysgenesis,
trabeculodysgenesis, irido-dysgenesis and corneodysgenesis. These may present either singly or
in some combination30. Surgical techniques commonly used for PCG are goniotomy, trabeculotomy,
trabeculectomy and trabeculotrabeculectomy. These procedures can offer equivalent IOP success
rates(64%~90%) when performed by experienced pediatric ophthalmology surgeons9,19,31-33.
Goniotomy cannot be performed safely in the presence of corneal edema34, meanwhile
trabeculotomy ab externo can be done even if the cornea is hazy. But the successful rates of the
two procedures depend on the type of angle anomaly30. Moreover, several types of complications
can occur after these procedures, notably intraocular hemorrhages, hypotony secondary to trauma
to the ciliary body and stripping of Descemet’s membrane6,33. In China, nearly all PCG patients
presented with advanced disease evidenced by large corneal diameters and cloudy cornea, mainly
because of limited medical conditions. The average corneal diameters at presentation in our study
were 13.43(0.7) mm in group 1 and 13.43(1.0) mm in group 2, and many of them presented
significant corneal oedema that precluded the details of structures beyond the cornea from detailed
visualization. These patients were not suitable for goniotomy and the more lower IOP control are
needed. Trabeculectomy is a procedure that most ophthalmologists are familiar with and is
technically easier than goniotomy or trabeculotomy. Therefore, despite higher incidence of
complications of trabeculectomy, it has been widely used in China to treat PCGs. Several studies
have reported good success rates of trabeculectomy with mitomycin-C in children, the success rate
ranging from 48%~95%, depending on the patient’s age, definition of success, duration of follow-up
and other factors30.
9
There are alternative choices. Sarkisian reported a 360° ab externo trabeculectomy using an
illuminated ophthalmic microcatheter for the treatment of primary congenital glaucoma 35. Tube
drainage surgery remains an important part of the therapeutic repertoire in paediatric glaucoma as it
offers the best chance of long-term IOP control in a small proportion of patients whose disease
relentlessly progresses despite conventional surgical treatment36. The threshold for drainage
surgery in challenging paediatric glaucoma cases has lowered in recent years. The reasons being
that results are more predictable and definitive than cyclodiode treatment and possibly better than
filtering surgery in infants37,38. However, despite infectious endophthalmitis and retinal detachment
which are potential complications following any incisional surgery, tube exposure is a unique
potential
problem
following
aqueous
shunt
implantation
that
can
lead
to
intraocular
infection39.Another reason for us not choosing these surgeries is that about the expensive costs
which couldn’t be afford by mangy rural patients.
Viscocanalostomy, one of the nonpenetrating techniques, has become an accepted surgical
treatment in POAG patients. Viscocanalostomy was proved to efficiently and safely reduce IOP in
medically uncontrolled POAG in a predominantly black and white population20,21,23,40,41. In the
viscocanalostomy technique, ①aqueous humor egressed from the anterior chamber through a thin
trabeculodescemetic membrane window into the scleral lake and from there through the newly
created orifices of the Schlemm canal in its lumen and into the physiologic collector channels;②
aqueous humor that passes through the trabeculodescemetic membrane window into the scleral
lake can diffuse into the uveoscleral outflow system that is adjacent to the lake. This surgery
10
prevents the need for full-thickness penetration and, in theory, minimizes postoperative
complications such as excessive drainage and endophthalmitis.
In primary congenital glaucoma, although the mechanisms is complicated, some theories proposed
that the pathology of the greatest resistance to aqueous outflow in infants and young children may
be at the level of Schlemm’s canal. So expansion of Schlemm’s canal may open a narrowed or
closed canal and possibly rupture the adjacent and poorly developed compact meshwork, thus
allowing a more direct flow of aqueous into the outflow system42.However, other theories are
contradictory43 While, during our viscocanalostomy surgery, an abundant percolation of aqueous
humor generally observed as the internal wall of Schlemm’s canal and juxtacanalicular connective
tissue peeled away. This phenomenon partially supported the former theories.
In our study, viscocanalostomy achieves good IOP reduction rate. Data showed that IOP drops
dramatically from 31.96(3.9) mmHg to 11.22(2.5) mmHg at the first day postoperatively in
viscocanalostomy group, and had no statistical difference with the trabeculectomy group(P>0.1).
Also, throughout the follow-up time, the mean IOP maintained at a normal level in both groups,
which was significant different with preoperative IOP and had no difference between the groups
(Figure 3 and Figure 4). Although complete surgical success rate of viscocanalostomy (45.9%) was
seemed lower than trabeculectomy(67.4%) in our study, but there was no statistical difference
between them. This corroborates findings from other studies in adult population with POAG24,41. But
the success rates of both surgeries in our study were lower than previous reports15,34,44. We
supposed that was because of the severity of the patients. The mean preoperative IOPs were
11
31.96(3.9) mmHg and 32.56(4.0) mmHg in two groups, while the patients’ horizontal corneal
diameters were 13.43(0.7) mm and 13.43(1.0) mm, respectively, which were larger than patients in
other studies18,25.The stage of the disease could possibly effect the prognosis.
MMC was used as an antimetabolite during trabeculectomy to avoid scarring. Although MMC
considerably increase the success rate, the potential side effects such as chronic hypotony, leakage
and infection are too high a risk for these very young patients.14 In viscocanalostomy group, we
didn’t use any antimetabolic grugs. Besides its mechanical effects on dilating and disrupting the wall
of SC, Healon GV (the viscoelastic material used in viscocanalostomy) possesses interesting
anti-inflammatory properties that depend on the concentration and molecular weight of sodium
hyaluronate, potentially playing an important role in postoperative antifibrosis procedure on the
surgical wound45. Although in our study, no major complications happen, we should alert the
potential complications with filtering surgery.
The main difficulty encountered in viscocanalostomy in these infantile eyes is the relatively thinner
limbal sclera than that in adults. Although the superficial scleral flap was relatively easily dissected,
the thickness of the deeper flap was decided only when the choroid could be seen 0.5 mm within
the distal border of the first flap. So, we ended up having to carry out much finer dissections than
those in adult eyes. Another difficulty is due to the enlarged corneal scleral limbus which makes us
couldn’t identify the Schlemm’s canal very easily or clearly.
Our retrospective, consecutive study has shown both procedures to be equally effective in lowering
12
IOP for a mean follow-up of 12 months. Viscocanalostomy is technically a more difficult surgery
than trabeculectomy. However, it seems to be a good surgical alternative, especially because it
prevents the need for full-thickness penetration and, in theory, minimizes postoperative
complications such as excessive drainage and endophthalmitis. Larger controlled studies with a
longer follow-up time are needed to further clarify the issue.
ACKNOWLEDGMENTS
We thank Pro. Robert Stegmann in Medical University of Southern Africa, Medunsa, South Africa;
and Pro.David Friedmann in Wilmer Eye Institute at Johns Hopkins,Columbia,USA for your great
helps to improve our surgical techniques which were discussed in the paper.
13
References:
1.Francois J. Congenital glaucoma and its inheritance. Ophthalmologica. 1980;181:61-73. PMID: 7219964
2.Taylor RH, Ainsworth JR, Evans AR, Levin AV. The epidemiology of pediatric glaucoma: the Toronto experience.
Journal Of Aapos. 1999;3:308-315. PMID: 10532577
3.Barsoum-Homsy M, Chevrette L. Incidence and prognosis of childhood glaucoma. A study of 63 cases.
Ophthalmology. 1986;93:1323-1327. PMID:3785892
4.Qiao CY, Wang LH, Tang X, Wang T, Yang DY, Wang NL. Epidemiology of hospitalized pediatric glaucoma
patients in Beijing Tongren Hospital. Chin Med J (Engl). 2009;122:1162-1166. PMID:19493464
5.Shaffer RN. Prognosis of goniotomy in primary infantile glaucoma (trabeculodysgenesis). Trans Am Ophthalmol Soc.
1982;80:321-325. PMID:7182965
6.Dietlein TS, Jacobi PC, Krieglstein GK. Prognosis of primary ab externo surgery for primary congenital glaucoma. Br
J Ophthalmol. 1999;83:317-322. PMID:10365040
7.DeLuise VP, Anderson DR. Primary infantile glaucoma (congenital glaucoma). Survey Of Ophthalmology.
1983;28:1-19. PMID:6353647
8.Gramer E, Tausch M, Kraemer C. Time of diagnosis, reoperations and long-term results of goniotomy in the treatment
of primary congenital glaucoma: a clinical study. Int Ophthalmol. 1996;20:117-123. PMID:9112175
9.Mendicino ME, Lynch MG, Drack A, Beck AD, Harbin T, Pollard Z, et al. Long-term surgical and visual outcomes in
primary congenital glaucoma: 360 degrees trabeculotomy versus goniotomy. Journal Of Aapos. 2000;4:205-210.
PMID:10951295
10.Bhade AV, Narang SK. Primary congenital glaucoma clinical presentation and evaluation of modified trabeculectomy.
Indian J Ophthalmol. 1987;35:265-270. PMID:3508788
11.Mandal AK, Prasad K, Naduvilath TJ. Surgical results and complications of mitomycin C-augmented trabeculectomy
in refractory developmental glaucoma. Ophthalmic Surg Lasers. 1999;30:473-480. PMID:9627644
12.Mandal AK, Walton DS, John T, Jayagandan A. Mitomycin C-augmented trabeculectomy in refractory congenital
glaucoma. Ophthalmology. 1997;104:996-1001, 1002-1003. PMID:9186441
13.Susanna RJ, Oltrogge EW, Carani JC, Nicolela MT. Mitomycin as adjunct chemotherapy with trabeculectomy in
congenital and developmental glaucomas. Journal Of Glaucoma. 1995;4:151-157. PMID:19920661
14.Rodrigues AM, Junior AP, Montezano FT, de Arruda MP, Prata JJ. Comparison between results of trabeculectomy in
primary congenital glaucoma with and without the use of mitomycin C. Journal Of Glaucoma. 2004;13:228-232.
PMID:15118468
15.Koraszewska-Matuszewska B, Samochowiec-Donocik E, Pieczara E, Lange E. [Trabeculectomy as the initial
procedure in primary congenital glaucoma]. Klin Oczna. 2000;102:331-334. PMID:11286107
16.Mandal AK, Naduvilath TJ, Jayagandan A. Surgical results of combined trabeculotomy-trabeculectomy for
developmental glaucoma. Ophthalmology. 1998;105:974-982. PMID:9627644
17.Costa LS, Costa RM. Combined trabeculotomy-trabeculectomy as a first surgical procedure for primary congenital
glaucoma. Ann Ophthalmol (Skokie). 2006;38:25-27. PMID:17200580
18.Campos-Mollo E, Moral-Cazalla R, Belmonte-Martinez J. [Combined trabeculotomy-trabeculectomy as the initial
surgical procedure of primary developmental glaucoma]. Arch Soc Esp Oftalmol. 2008;83:479-485. PMID:18661444
19.Essuman VA, Braimah IZ, Ndanu TA, Ntim-Amponsah CT. Combined trabeculotomy and trabeculectomy: outcome
for primary congenital glaucoma in a West African population. Eye (Lond). 2010. PMID:21057523
20.Stegmann R, Pienaar A, Miller D. Viscocanalostomy for open-angle glaucoma in black African patients. J Cataract
Refract Surg. 1999;25:316-322. PMID:10079435
14
21.Yalvac IS, Sahin M, Eksioglu U, Midillioglu IK, Aslan BS, Duman S. Primary viscocanalostomy versus
trabeculectomy for primary open-angle glaucoma: three-year prospective randomized clinical trial. J Cataract Refract
Surg. 2004;30:2050-2057. PMID:15474813
22.Park M, Tanito M, Nishikawa M, Hayashi K, Chichara E. Combined viscocanalostomy and cataract surgery compared
with cataract surgery in Japanese patients with glaucoma. Journal Of Glaucoma. 2004;13:55-61. PMID:14704545
23.Wishart PK, Wishart MS, Choudhary A, Grierson I. Long-term results of viscocanalostomy in pseudoexfoliative and
primary open angle glaucoma. Clin Experiment Ophthalmol. 2008;36:148-155. PMID:18352871
24.Gilmour DF, Manners TD, Devonport H, Varga Z, Solebo AL, Miles J. Viscocanalostomy versus trabeculectomy for
primary open angle glaucoma: 4-year prospective randomized clinical trial. Eye (Lond). 2009;23:1802-1807.
PMID:17293790
25.Noureddin BN, El-Haibi CP, Cheikha A, Bashshur ZF. Viscocanalostomy versus trabeculotomy ab externo in primary
congenital glaucoma: 1-year follow-up of a prospective controlled pilot study. Br J Ophthalmol. 2006;90:1281-1285.
PMID:16837543
26.Denis D, Pommier S, Coste R, Fogliarini C, Benso C, Cornand E. [Deep sclerectomy in congenital glaucoma: results
of a study lasting more than 3 years]. Journal Francais D Ophtalmologie. 2008;31:173-179. PMID:18401318
27.Tanimoto SA, Brandt JD. Options in pediatric glaucoma after angle surgery has failed. Curr Opin Ophthalmol.
2006;17:132-137. PMID:16552247
28.Sidoti PA, Belmonte SJ, Liebmann JM, Ritch R. Trabeculectomy with mitomycin-C in the treatment of pediatric
glaucomas. Ophthalmology. 2000;107:422-429. PMID:10711876
29.Feusier M, Roy S, Mermoud A. Deep sclerectomy combined with trabeculectomy in pediatric glaucoma.
Ophthalmology. 2009;116:30-38. PMID:19010550
30.Mandal AK, Chakrabarti D. Update on congenital glaucoma. Indian J Ophthalmol. 2011;59 Suppl:S148-S157.
PMID:21150027
31.Alsheikheh A, Klink J, Klink T, Steffen H, Grehn F. Long-term results of surgery in childhood glaucoma. Graefes
Arch Clin Exp Ophthalmol. 2007;245:195-203. PMID:16983524
32.Zhang X, Du S, Fan Q, Peng S, Yu M, Ge J. Long-term surgical outcomes of primary congenital glaucoma in China.
Clinics (Sao Paulo). 2009;64:543-551. PMID:19578658
33.Filous A, Brunova B. Results of the modified trabeculotomy in the treatment of primary congenital glaucoma. Journal
Of Aapos. 2002;6:182-186. PMID:12075295
34.Roche O, Beby F, Parsa A, Orssaud C, Dufier JL, Parsa CF. Nonpenetrating external trabeculectomy for congenital
glaucoma: a retrospective study. Ophthalmology. 2007;114:1994-1999. PMID:17980742
35.Sarkisian SJ. An illuminated microcatheter for 360-degree trabeculectomy in congenital glaucoma: a retrospective
case series. Journal Of Aapos. 2010;14:412-416. PMID:21035067
36.Ishida K, Mandal AK, Netland PA. Glaucoma drainage implants in pediatric patients. Ophthalmol Clin North Am.
2005;18:431-442. PMID:16055000
37.Beck AD, Freedman S, Kammer J, Jin J. Aqueous shunt devices compared with trabeculectomy with Mitomycin-C
for children in the first two years of life. American Journal Of Ophthalmology. 2003;136:994-1000. PMID:14644208
38.Ou Y, Yu F, Law SK, Coleman AL, Caprioli J. Outcomes of Ahmed glaucoma valve implantation in children with
primary congenital glaucoma. Arch Ophthalmol. 2009;127:1436-1441. PMID:19901208
39.Al-Mobarak F, Khan AO. Complications and 2-year valve survival following Ahmed valve implantation during the
first 2 years of life. Br J Ophthalmol. 2009;93:795-798. PMID:19174395
40.Carassa RG, Bettin P, Fiori M, Brancato R. Viscocanalostomy: a pilot study. European Journal Of Ophthalmology.
1998;8:57-61. PMID:9673471
41.Noureddin BN, El-Haibi CP, Cheikha A, Bashshur ZF. Viscocanalostomy versus trabeculotomy ab externo in primary
15
congenital glaucoma: 1-year follow-up of a prospective controlled pilot study. Br J Ophthalmol. 2006;90:1281-1285.
PMID:16837543
42.Grant WM. Experimental aqueous perfusion in enucleated human eyes. Arch Ophthalmol. 1963;69:783-801.
PMID:13949877
43.Rojas B, Ramirez AI, De-Hoz R, Salazar JJ, Remirez JM, Trivino A. [Structural changes of the anterior chamber
angle in primary congenital glaucoma with respect to normal development]. Arch Soc Esp Oftalmol. 2006;81:65-71.
PMID:16511712
44.Tamcelik N, Ozkiris A. Long-term results of viscotrabeculotomy in congenital glaucoma: comparison to classical
trabeculotomy. Br J Ophthalmol. 2008;92:36-39. PMID:18156375
45.Stangos AN, Whatham AR, Sunaric-Megevand G. Primary viscocanalostomy for juvenile open-angle glaucoma.
American Journal Of Ophthalmology. 2005;140:490-496. PMID:16084786
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Figure Legends
Figure 1 The main procedures of viscocanalostomy. (A)The cornea was enlarged and the
edema was severe that the iris was hardly seen. (B) A tongue-shaped superficial scleral flap
measuring 5×4 mm, one third of the full sclera thickness, about 1.0mm into clear cornea. (C) (D) A
deep scleral flap measuring 4×3 mm, leaving only a very thin layer of sclera. (E) A blunt end of a
20G needle used to open the inner wall of the Schlemm’s canal. (F)Inner wall of the Schlemm’s
canal and juxtacanalicular connective tissure was peeled away by forceps.(G) A transparent
membrane was clamped with the forceps.(H) The deeper sclera flap was gently cut at the level of
the trabeculo- Descemet membrane. (I) High-viscosity sodium hyaluronate was injected into the
Schlemm canal at each ostium.
Figure 2 Age at operation time(month).The age difference between two groups is not
significant(P>0.1)
Figure 3 Mean IOP over time in eyes having viscocanalostomy or trabeculectomy. The decrease
of the IOP at each follow-up point was statistically obvious in both groups.
Figure 4 Mean IOP over time in eyes having viscocanalostomy or trabeculectomy. The IOP
difference between the two groups is not significant (P>0.1)
17
Figure 5 Mean corneal diameter in two groups. The postoperative horizontal corneal diameters in
both groups were significantly decreased than preoperative ones.
Figure 6 The complete success rate in both groups. The difference between group 1 and group 2 is
not statistically significant.
18
Table 1 Characteristics of the patients
Group 1
Group 2
No. of patients
18
25
No. of eyes
27
39
13.31(7.8)
14.86(8.3)
Female
11
12
Male
7
13
9/18(50%)
14/25(56%)
Mean(SD) age(months)
Gender
Bilateral glaucoma
19
Table 2 Mean intraocular pressure decrease in groups of patients undergoing
viscocanalostomy and trabeculectomy
Group 1
Pre-op
Group 2
IOP
IOP decrease
IOP
IOP decrease
mean(SD)
mean
mean(SD)
mean
(mmHg)
(mmHg)
(mmHg)
(mmHg)
P value
P value
31.96(3.9)
32.56(4.0)
Post-op
Day 1
11.22(2.5)
20.74
<0.001
10.44(3.8)
22.12
<0.001
Week 1
12.85(2.4)
19.11
<0.001
12.13(2.5)
20.43
<0.001
Month 1
14.67(2.5)
17.29
<0.001
13.72(2.8)
18.84
<0.001
Month 6
16.44(3.2)
15.52
<0.001
15.44(2.7)
17.12
<0.001
Month12
16.78(2.2)
15.18
<0.001
15.77(2.6)
16.79
<0.001
20
Table 3 Postoperative complications
Eyes, n(%)
Group 1
Group 2
(n=27)
(n=39)
Hypotony†
1（3.7）
6（15.4）
0.226
Hyphemia
1（3.7）
3（7.7）
0.639
Cataract
0
5 (12.8)
0.111
Choroid effusion
0
4(10.2)
0.139
DM detachment
2（7.4）
0
0.164
Complication
DM=Descemet’s membrane
†IOP≤5mmHg
*Fisher’s test
21
P value*
Figure 1
22
Figure 2
23
Figure 3
24
Figure 4
25
Figure 5
26
Figure 6
27
28