2nd Consensus Meeting:
Glaucoma Surgery. Open Angle Glaucoma

Fort Lauderdale, FL, April 30, 2005

Download your free copy of Consensus 2 through the IGR website

cons2edited 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.
ISBN-13: 978-90-6299-203-4
Published by Kugler Publications.
Click here for more information on all publications in the Consensus series.

See meeting photos

Consensus Statements

Indications for Glaucoma Surgery

 

  • 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
    IOP.
    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
    visits.
  • 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
    years.
  • 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
    hours.
  • 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)

Wound Healing

 

  • 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
    filtration.
  • 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
    scarring process.
  • 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.

Trabeculectomy

 

  • 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
    eyes.
  • 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
    procedures.
  • 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
    patient morbidity.
  • 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.

Combined Cataract/Trabeculectomy

 

  • 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
    choice.
  • 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)

 

  • 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
Glaucoma

 

  • Lower IOP can be achieved with trabeculectomy than with NPGDS.
  • Short-term
    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
    postoperative intervention.

Cyclodestruction

 

  • 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.
  • Transscleral cyclophotocoagulation
    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.
  • Post-operative
    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.
    b. Cyclodestructive
    procedures reduce aqueous production.
  • GDD implantation requires greater surgical
    training and is a more extensive procedure than cyclodestruction.
  • GDD implantation
    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
    currently available.

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