edited by Robert N. Weinreb and Jonathan G. Crowston
2005. xiv and 140 pages with 9 tables and 2 figures, of which 1in full color. Hardbound.
ISBN-10: 90 6299 203 X.
Published by Kugler Publications.
Click here for more information on all publications in the Consensus series.
The decision for surgery should consider the risk/benefit ratio. Although
a lower IOP is generally considered beneficial to the eye, the risk of vision
loss without surgery must outweigh the risk of vision loss with surgery.
Surgery for glaucoma is indicated when:
a. Optimum medical therapy and/or laser surgery fails to sufficiently lower
b. A patient does not have access to or cannot comply with medical therapy.
Clinicians should generally measure IOP more than once and preferably at
different times of day when establishing baseline IOP prior to surgery. When
IOP is markedly elevated, a single determination may be sufficient.
Progression of glaucoma, considering both the structural and functional
integrity of the optic nerve, is clearly a threat to vision and strongly influences
the threshold for surgery.
Ongoing care of the patient with glaucoma requires careful periodic evaluation
of structure and function.
Efforts should be directed at estimating the rate or risk of progression.
A greater rate or risk of progression may lower the threshold for surgery but
must be balanced against the risk and benefits of surgery and the life expectancy
of the patient. Comment: An elderly patient with slow progression may suffer no effect
on quality of life during his/her lifetime. Comment: Advancing glaucomatous optic disc damage or retinal nerve fiber
loss without detected visual loss is progression and can in certain circumstances
be an indication for surgery.
Risk factors for progression of glaucoma are emerging from prospective studies.
(AGIS-older age, lower education, male sex, diabetes; CNTGS-female sex, migraine;
EMGT- high IOP, pseudoexfoliation, worsening visual fields during follow up,
disc hemorrhage, advanced stage of disease.) Presence of these risk factors
may alter target IOP or lower the threshold to surgery.
Comment: Fellow eye vision loss from glaucoma may lower the threshold
IOP for consideration of surgery. It is not clear that it is a risk factor for
threat to vision. Comment: Family history of blindness from glaucoma is not a known risk
factor for vision loss, but such patients warrant close observation.
Primary surgery may be indicated on the basis of socioeconomic or logistic
constraints. Comment: There is insufficient evidence to recommend primary surgery
in all patients.
Patients who are unable or unwilling to use their medical therapy as prescribed
represent failures of treatment efficacy and may need surgery to achieve consistent
IOP reduction, even when isolated IOP measurements appears normal at office
The extent and location of damage may alter the threshold for surgery. Patients
with advanced damage or damage threatening central vision may require lower
IOP than those with early disease.
Argon Laser Trabeculoplasty
Laser trabeculoplasty (LTP) with diode, or frequency doubled Q-switched
Nd:YAG are effective methods to lower IOP. (1, A)
The principal indication for laser trabeculoplasty remains the failure of
medical therapy to sustain acceptable IOP levels in adult eyes with POAG or
intolerance of medical therapy. However, in appropriate cases LTP may be used
as a primary therapy. (III, A)
Although IOP lowering after LTP tends to wane with time, it may produce
clinically significant IOP reduction in phakic eyes for up to several years
(II, A) Comment: LTP often is effective in pseudophakic eyes for up to several
Postoperative monitoring of IOP and follow up treatment of intraocular pressure
spikes is appropriate. (III, A) Comment: IOP spikes tend to occur within the first few postoperative
Uveitis, ICE syndrome, congenital anomalies of the anterior chamber angle,
and poor visualization of angle structures are contraindications for LTP, while
age < 40 year, angle recession, traumatic glaucoma and high myopia are relative
contraindications. (III, A)
All commonly employed methods of LTP appear to be equivalent with respect
to short-term side effects and IOP lowering. (III, A)
There is longer follow-up data available for argon laser trabeculoplasty
(ALT) than for selective laser trabeculoplasty (SLT). Randomized studies comparing
these two modalities are not yet available. (III, A)
Retreatment with ALT (applying additional laser spots to areas of the meshwork
previously treated) is likely to be ineffective and perhaps detrimental. Although
retreatment with SLT has a theoretical advantage, studies to prove this have
not yet been reported. (III, A)
Excessive healing at the conjunctiva-Tenon’s fascia-episcleral interface
is the major cause of inadequate long term IOP lowering after trabeculectomy.
Risk factors for scarring should be evaluated and documented in all patients
prior to undergoing glaucoma filtration surgery (see appendix). Comment: Conjunctival inflammation should be minimized prior to surgery.
The use of adjunctive antifibrosis agents should be considered in most patients
undergoing trabeculectomy and should be titrated against the estimated risk
of postoperative scar formation and estimated risk for postoperative complications.Comment: Although some patients may have a successful result without
adjunctive antifibrosis use, there is no systematic method for identifying these
patients. Comment: Different antifibrotic agents may be associated with different
risks and benefits. MMC may be a more effective adjunct than 5-FU but is associated
greater complications. Comment: A large antifibrotic treatment area is desirable to achieve
diffuse non-cystic blebs with a lower risk of discomfort and leakage. Comment: Complications related to the use of antifibrosis agents are
usually related to excessive inhibition of wound healing, which may result in
or prolong early (wound leak, hypotony, shallow anterior chamber, choroidal
detachment, etc.) and late (hyptonony maculopathy, wound leak, and bleb-related
ocular infection, etc.) complications.
Modern trabeculectomy techniques that include the use of lasered / releasable
/ adjustable sutures should be employed to minimize the complications of excessive
Early intervention (subconjunctival 5-FU and increased topical steroids)
is recommended in eyes with evidence of active scar formation (conjunctival
hyperemia and anterior chamber inflammation) Comment: Use of subconjunctival 5-FU in eyes with a wound leak, corneal
defect or ocular hypotony should be cautioned. Comment: Postoperative IOP elevation typically occurs after significant
scarring has already taken place. As the scarring process might be slowed with
additional measures, but not likely reversed, it is advised to intervene prior
to an actual IOP rise, based on signs indicating the likelihood of an active
Antifibrosis use is associated with enhanced bleb formation and lower intraocular
pressure. However, they also have an increased long-term risk. Comment:
It is essential to inform patients about the signs and symptoms of ocular infection
and advise them that they should seek ophthalmological advice urgently, should
they occur. Long term follow up of these eyes is advisable.
Incisional surgery for glaucoma is indicated when medical therapy and/or
laser fail to sufficiently lower IOP or the patient does not have access to,
or cannot comply with, other forms of therapy. Comment: Primary surgery may also be indicated on the basis of socioeconomic
or logistical constraints.
Trabeculectomy is the incisional procedure of choice in previously unoperated
Postoperative hypotony should be avoided and sequential IOP adjustment should
be performed with suture modification.
Trabeculectomy provides better and more sustained IOP lowering than non-penetrating
Although adjunctive antifibrosis agents enhance the success of trabeculectomy,
their risk/benefit ratio should be assessed for each individual patient prior
to use. This applies to initial and repeat surgeries.
Preoperative conjunctival inflammation and postoperative conjunctival and
intraocular inflammation should be suppressed vigorously with glucocorticoids.
Trabeculectomy success is highly dependent on postoperative care and management. Comment: Early recognition of postoperative complications and timely,
appropriate intervention enhances the success rate of surgery and minimizes
Patients that have had trabeculectomy should be warned of the signs and
symptoms of late bleb-related ocular infection and should be counseled to seek
immediate attention should these occur.
A combined procedure is usually indicated when surgery for intraocular pressure
(IOP) lowering is appropriate and a visually significant cataract is also present.Comment: Patients with glaucoma who are undergoing cataract do not necessarily require
combined surgery. To avoid the complications associated with increased postoperative IOP, however, combined procedures should be considered in those patients on multiple
medications or with advanced glaucomatous optic neuropathy.
The indication for
combined surgery in an individual patient should take into account the level of
desired IOP control after surgery, the severity of glaucoma and the anticipated
benefit in quality of vision after cataract extraction. Comment: Visual rehabilitation
may take longer following combined surgery compared to cataract surgery alone.
There is limited evidence to differentiate a one-site vs. a two-site approach for
combined surgery. Therefore, surgeon preference and experience will dictate the
There is limited evidence to differentiate a limbal vs. a fornix-based
conjunctival incision for combined surgery. Therefore, surgeon preference and experience
will dictate the choice.
Mitomycin-C should be considered in all combined procedures
to improve the chance of successful IOP control, unless there is a clear contraindication
for its use. Comment: Evidence for the use of adjunctive 5-fluorouracil data is
limited and the bulk of the evidence suggests that it does not work well or at all.
Combined procedures are less successful for IOP reduction than trabeculectomy
alone. Comment: Subsequent cataract surgery may compromise the success of earlier trabeculectomy surgery.
In patients with cataract and stable glaucoma, a clear
corneal approach is preferable in patients who may require subsequent trabeculectomy.
Aqueous Shunting Procedures with Glaucoma Drainage Devices
Glaucoma drainage devices (GGD) are indicated when trabeculectomy is unlikely
to be successful or because of socioeconomic or logistical issues. Comment: In some
patients, GDDs should be considered for socioeconomic or logistical issues relating
to safety, follow-up care, etc.
The restriction of flow of aqueous humor from
the eye is important in the prevention of immediate postoperative hypotony. Comment: GDDs that do not have mechanisms to restrict aqueous flow require a suture ligature
or internal stent or other flow restricting mechanism.
In general, larger surface
areas of the plate are associated with lower IOP.
Scar formation around the plate
is the main cause of long-term device failure. Comment: Antifibrotic agents have
not been shown to improve long-term success when used intraoperatively or postoperatively.
Pars plana positioning of a GDD should be considered in a patient with a prior
pars plana vitrectomy or in patient in whom a tube cannot be safely inserted into
the anterior chamber.
The preponderance of evidence addresses GDDs that drain
to a posterior reservoir. Comment: Anterior drainage devices are under study. One
should not extrapolate data from posterior drainage to anterior drainage devices.
Comparison of Procedures: Trabeculectomy versus Aqueous Shunting Procedures with
Glaucoma Drainage Devices
Trabeculectomy with MMC is less expensive and requires
less conjunctival dissection than aqueous shunting procedures. Comment: Cost of GDDs vary significantly throughout the world.
With increased conjunctival scarring,
the success of MMC trabeculectomy is reduced. Aqueous shunting procedures should
be considered in patients with failed MMC trabeculectomy.
In general, lower IOP
can be achieved with MMC trabeculectomy compared with aqueous shunting procedures,
but good clinical studies are lacking. Comment: There are currently limited data
from prospective randomized comparisons between MMC trabeculectomy and aqueous shunting
procedures. To adequately compare MMC trabeculectomy with aqueous shunting procedures,
comparable patient populations are required.
Bleb related complications are less
prevalent after aqueous shunting procedures. However, aqueous shunting procedures
introduce a distinct set of complications including tube erosion or plate erosion,
endothelial decompensation and strabismus.
Aqueous shunting procedures (ASPs)
should be considered in patients at high risk of MMC-related postoperative complications.
These include severe lid margin disease, chronic contact lens wear, and a history
of blebitis or bleb-related endophthalmitis.
Non Penetrating Glaucoma Drainage Surgery
NPGDS provides an alternative surgical approach to trabeculectomy for
moderate lowering of IOP in glaucoma patients.
Post-operative Nd:YAG laser goniopuncture
may be an integral part of the procedure. Comment: Laser goniopuncture is akin to
flap suture manipulations following trabeculectomy.
Unlike viscocanalostomy, external
filtration with deep sclerectomy may enhance the success of the procedure.
Deep sclerectomy may provide a lower IOP than viscocanalostomy, although the evidence
for this is limited.
Failed NPGDS may compromise the success of subsequent trabeculectomy.
Comparison of Trabeculectomy with Non-Penetrating Drainage Glaucoma Surgery in Open-Angle
Lower IOP can be achieved with trabeculectomy than with NPGDS.
complications associated with NPGDS may be fewer and less severe.
NPGDS is technically
more challenging, with a longer operative time. Comment: Both procedures may require
Of the cyclodestructive procedures,
laser diode cyclophotocoagulation with the G-probe is the procedure of choice for
refractory glaucoma when trabeculectomy and drainage implants have a high probability
for failure or have high risk of surgical complications.
may be considered when maximal medical therapy, trabeculectomy or drainage implant
surgery is not possible due to resource limitations.
Prior to transscleral cyclophotocoagulation
treatment, transillumination of the globe to reveal the location of the ciliary
body may be useful, especially in morphologically abnormal eyes.
treatment consisting of topical steroids and cycloplegics is suggested to minimize
post-operative complications and discomfort. Comment: The effectiveness of treatment
should be assessed after 3-4 weeks, at which time re-treatment may be considered.Comment: Less intense laser therapy on a repeated basis rather than a single high
dose treatment is suggested to minimize complications of treatment.
Comparison of Cyclophotocoagulation and Glaucoma Drainage Device Implantation
Mechanism of action:
a. Glaucoma drainage devices (GDD) increase aqueous humor outflow.
procedures reduce aqueous production.
GDD implantation requires greater surgical
training and is a more extensive procedure than cyclodestruction.
requires greater postoperative care than cyclodestruction.
GDD implantation should
be performed in an operating room while cyclodestruction can be performed in the
office, minor surgery area or in the operating room.
The marginal cost of GDD
implantation is more expensive than cyclodestruction. The initial cost of cyclodestruction
related to the purchase of the device used for the procedure may be greater than
that with GDD implantation.
Preoperative visual acuity may impact which of these
two treatment modalities are preferred. All other things being equal, GDD are more
commonly used for patients with better visual acuity and/or visual potential relative
to cyclodestructive procedures. Strong evidence in support of this practice is not
Don’t miss any WGA news! Subscribe now to the WGA newsletter to stay up to date with all WGA activities.