Review of Glaucoma Surgery Clinical Trials

1. Essentials of Glaucoma Therapy
2. Surgical Trials and Regulatory Insights
3. Review of Glaucoma Surgery Clinical Trials

←Suprachoroidal Devices

United States Food and Drug Administration Regulation of Ophthalmic Devices →

Primary authors	Travis C. Rumery, DO David C. Musch, PhD, MPH Joshua D. Stein, MD, MS

There have been several landmark randomized clinical trials that have generated important insights into the safety and efficacy of medical therapy, laser therapy, and surgical therapy for the treatment of glaucoma. In this chapter, we will highlight several of these key randomized clinical trials by describing the rationale for the study, types of patients recruited to participate, interventions that the enrollees were randomized to receive, important primary and secondary outcomes, and implications of the trials’ results. The following randomized clinical trials will be summarized in this chapter:

1. Medical therapy versus laser surgery
   1. Moorfields Primary Treatment Trial (MPTT)
   2. Glaucoma Laser Trial (GLT)
   3. Glaucoma Laser Trial Follow-Up Study (GLTFU)
2. Medical therapy versus incisional surgery
   1. Scottish Glaucoma Trial (SGT)
   2. Moorfields Primary Treatment Trial (MPTT)
   3. Collaborative initial Glaucoma Treatment Study (CIGTS)
3. Laser surgery versus incisional surgery
   1. Advanced Glaucoma Intervention Study (AGIS)
   2. Moorfields Primary Treatment Trial (MPTT)
4. Incisional surgery trials
   1. Ahmed versus Baerveldt Comparison Trial (ABC)
   2. Fluorouracil Filtering Surgery Study (FFSS)
   3. Tube versus Trabeculectomy Study (TVT)
   4. Primary Tube versus Trabeculectomy Study (PTVT)

Main Study Purpose

To test whether it was justifiable to continue with the conventional practice of using medical therapy as the initial treatment compared with using trabeculectomy as the initial treatment of patients with open-angle glaucoma.

Location

Glasgow, Scotland, United Kingdom.

Study Population

Patients with newly diagnosed primary open-angle glaucoma (OAG), as well as those with exfoliation syndrome glaucoma.

Interventions the Participants Were Randomized to Receive

1. Medical therapy (up to a maximum of 3 different topical or systemic drugs) followed by trabeculectomy (without antimetabolites) if medical therapy failed.
2. Trabeculectomy (without antimetabolites) followed by medical therapy,­ if trabeculotomy failed.

Study Design

• Multicenter, randomized clinical trial.
• 116 patients enrolled between 1980 and 1985.
• 99 patients (53 in the medical therapy group and 46 in the trabecu-lectomy group) completed at least 1 year in the trial.

Inclusion Criteria

• Untreated intraocular pressure (IOP) ≥26 mm Hg (Goldmann applanation tonometry) on 2 occasions.
• Visual field (VF) defects characteristic of glaucoma.

Length of Follow-Up

Maximum follow-up of 7 years (mean: 4.6 years).

Results

Trabeculectomy group had a greater decrease in IOP than the medically treated group at 1 year.

At a mean follow-up of 4.6 years, the trabeculectomy group had:

• Less VF loss than the medical group.
• No difference in final visual acuity (VA) versus the medically treated group.

Implications

Showed benefit to early trabeculectomy in the management of newly diagnosed OAG patients.

Notes

This trial preceded the use of many commonly used topical glaucoma medications including prostaglandin analogues, alpha agonists, and topical carbonic anhydrase inhibitors (CAI).

Moorfields Primary Treatment Trial

Main Study Purpose

To compare the efficacy of medical therapy, laser trabeculoplasty, and trabeculectomy without antimetabolites as primary treatment for patients with OAG.

Location

London, England.

Study Population

Patients with chronic, untreated OAG.

Interventions the Participants Were Randomized to Receive

1. Initial medical therapy: pilocarpine and/or a sympathomimetic and/ or timolol, as the initial therapy; increasing to maximum tolerated medical therapy, which could, in individual cases, require all 3 of these topical medications and an oral CAI.
2. Initial laser trabeculoplasty: 2 treatments, each consisting of 50 burns over 180 degrees of the anterior trabecular meshwork, separated by an interval of 2 weeks (treated with pilocarpine for 2 weeks after therapy, which was tapered if IOP allowed, but continued as adjuvant therapy if IOP was not controlled by laser alone).
3. Initial trabeculectomy: trabeculectomy without antimetabolites using either a fornix- or limbal-based conjunctival flap.

Study Design

• Single center, randomized, clinical trial.
• 168 patients (56: medical therapy group, 55: laser therapy group, and

Inclusion Criteria

• IOP ≥24 mm Hg on 2 occasions.
• Cup-to-disc ratio (C/D) >0.6, and/or notching, and/or pallor of the neuroretinal rim.
• Glaucomatous field loss on automated perimetry.
• Open drainage angle.

Length of Follow-Up

Minimum of 5 years.

Results

• Trabeculectomy group had the greatest IOP decrease (from 34 to 14.1 mm Hg for the trabeculectomy group, 35 to 18.5 mm Hg for the laser group, and 35 to 18.5 mm Hg for the medical therapy group) at 5 years.
• Equal IOP decrease in the medical and trabeculectomy groups at 5 years (see above).
• No difference in final VA among all groups at 5 years.
• Medical and trabeculoplasty groups had greater VF loss as compared with the trabeculectomy group at 5 years.

Implications

• Showed benefit of early trabeculectomy in the management of newly diagnosed OAG.
• Suggested a relationship between progression of VF loss and the degree of IOP lowering in OAG patients.

Notes

• This trial preceded the use of many commonly used topical glaucoma medications, including prostaglandin analogues, alpha agonists, and topical CAIs.
• Antimetabolites were not used in this study.
• Humphrey visual field (HVF) testing was not available for the entire follow-up period to allow for adequate data to determine progression with the HVF.
• Success = IOP had been reduced to 22 mm Hg or less by 3 months and maintained below that level.
• Failure = IOP was greater than 22 mm Hg on 2 repeated occasions.

Glaucoma Laser Trial and Glaucoma Laser Trial Follow-Up Study

Main Study Purpose

To compare the safety and efficacy of argon laser trabeculoplasty (ALT) and topical glaucoma medications for controlling IOP in patients with newly diagnosed primary open-angle glaucoma (POAG).

Location

United States.

Study Population

Individuals with newly diagnosed bilateral POAG.

Interventions the Participants Were Randomized to Receive

1. ALT followed by topical glaucoma medications if needed. ALT treat-ment consisted of 2 treatments, each consisting of 48 burns (45 to 50 allowed) over 180 degrees of the trabecular meshwork (360 degrees covered between the 2 treatments).
2. Stepwise medical regimen: timolol 0.5% twice daily (step 1) → dipivefrin (step 2) → low-dose pilocarpine* (step 3) → high-dose pilocarpine♦ (step 4) → timolol with high-dose pilocarpine (step 5) → dipivefrin with high-dose pilocarpine (step 6) → ophthalmologist’s discretion (step 7). *2% if brown iris, 1% otherwise. ♦4% if brown iris, 2% otherwise.

Study Design

• Multicenter, randomized, clinical trial.
• Glaucoma Laser Trial (GLT): 271 patients, 542 eyes (271 eyes in each group, 1 eye randomized to each group) were enrolled between 1984 and 1987 with follow-up ending in November 1989.
• Glaucoma Laser Trial Follow-Up Study (GLTFU): 203 patients (406 eyes) from the original GLT were followed between December 1990 and August 1993.

Inclusion Criteria

• Age ≥35 years.
• IOP ≥22 mm Hg, bilaterally, on 2 successive visits.
• Glaucomatous VF loss in at least one eye or marked (C/D ≥ 0.8) disc changes in the presence of marked (≥31 mm Hg) IOP elevation.
• Intereye ratio of IOP ≤ 1.50.
• Best corrected visual acuity (BCVA) ≥ 20/70 in each eye.
• No signs of pigmentary or exfoliation syndrome glaucoma.
• No history of regular treatment with glaucoma medications within 6 months.

Exclusion Criteria

Evidence of secondary glaucomas, including pigmentary or exfoliative glaucoma.

Length of Follow-Up

GLT: 5 years. GLTFU: mean follow-up of 7 years (maximum: 9 years).

Funding

National Eye Institute, National Institutes of Health.

Results

• Initial treatment with ALT was at least as effective as initial treatment with timolol. ALT group had 1.2 mm Hg greater reduction in IOP on average over all study times. ALT group showed a small benefit in VF preservation averaged over all study times. ALT group showed less optic nerve deterioration averaged over all study times.
• Both groups had a similar decrease in VA by approximately 0.2 to 1 line over the mean follow-up period of 7 years.
• ALT group required less antiglaucoma medication (62% of the total number of medication days for the medical therapy group) compared with the medical therapy group through the mean follow-up period of 7 years.
• Transient increase in IOP and formation of peripheral anterior synechiae (PAS) were 2 side effects from ALT. Patients who developed PAS had similar or better IOP reduction, similar VF status, and simi-lar medical and surgical history as those patients who did not develop PAS throughout follow-up.

Implications

Provided evidence that ALT is a reasonable alternative to topical glaucoma medications as initial treatment for POAG.

Notes

• Over half of patients initially treated with ALT required medical treat-ment of glaucoma at 2 years.
• This trial preceded the use of many commonly used topical glaucoma medication including prostaglandin analogues, alpha agonists, and topi-cal CAIs.
• There might have been crossover of medication effects as treatment randomization was by eyes, not patients.

Fluorouracil Filtering Surgery Study

Main Study Purpose

To determine the success of using postoperative subconjunctival injections of 5-fluorouracil (5-FU) in patients undergoing filtering surgery.

Location

United States.

Study Population

Patients with uncontrolled glaucoma and guarded prognosis for filter-ing surgery (aphakic and pseudophakic eyes, and phakic eyes after failed filtering surgery).

Interventions the Participants Were Randomized to Receive

1. Trabeculectomy without postoperative 5-FU.
2. Trabeculectomy augmented with a postoperative regimen of subcon-junctival 5-FU.

Study Design

• Multicenter, randomized, clinical trial.
• 213 (108 in the trabeculectomy without 5-FU group, 105 in the trabe-culectomy with 5-FU group) were enrolled between 1985 and 1988.

Inclusion Criteria

• Uncontrolled glaucoma (IOP > 21 mm Hg).
• Patients who had undergone prior cataract extraction or had under-gone at least one unsuccessful filtering procedure in a phakic eye.

Exclusion Criteria

Age <18 years, patients who had previously received 5 -FU systemically or in the study eye, anterior segment neovascularization (NV) and dislocated lenses.

Length of Follow-Up

Up to 8 years.

Funding

• National Eye Institute, National Institutes of Health.
• Several institutional grants from participating centers.

Results

• The 5-FU group was more likely to attain IOP control and to avoid reoperation through 5 years.
• 5-FU reduced the 5-year failure rate following trabeculectomy: 51% of patients who received 5-FU failed compared with 74% in the trabeculectomy without 5-FU group.
• Risk factors for surgical failure included high preoperative IOP, short time interval since last surgery involving conjunctival manipulation, number of previous surgeries with conjunctival manipulation, and Hispanic ancestry.
• The 5-FU group had a higher incidence of late bleb leaks (9% versus 2%) through 5 years.

Implications

• This study supported the benefits of adjunctive antifibrotic use in improving the success of trabeculectomy surgery.
• Further investigations of other antifibrotic medications such as mitomycin C (MMC) were undertaken as a result of this study.

Notes

• Failure = reoperation for control of IOP or an IOP >21 mm Hg at or after the first-year examination.
• None of these patients had intraoperative antimetabolites.
• Eyes in the 5-FU group received a complex regimen consisting of 5.0 mg (0.5 mL) injections of 10-mg/ml 5-FU solution twice daily on postoperative days 1 to 7 and once daily on postoperative days 8 to 14.

Advanced Glaucoma Intervention Study

Main Study Purpose

To determine the most effective way to manage patients with advanced OAG.

Location

United States.

Study Population

Patients with medically uncontrolled OAG.

Interventions the Participants Were Randomized to Receive

1. Argon laser trabeculoplasty was given as first-line treatment. If ineffective, this was followed by trabeculectomy and, when necessary, a second trabeculectomy (ATT).
2. Trabeculectomy*, was given as first-line treatment. If ineffective, this was followed by ALT, and when necessary, followed by a second trabeculectomy (TAT).

*Antimetabolites were used very sparingly in initial trabeculectomies and with greater frequency in subsequent trabeculectomies.

Study Design

• Multicenter, randomized, clinical trial.
• 591 patients (789 eyes; 404 in the ATT group and 385 in the TAT group) were enrolled between 1988 and 1992.

Inclusion Criteria

• Age 35 to 80 years.
• Eyes had to be phakic and have advanced OAG.
• On maximal medical therapy, at least 1 medication from each of 3 groups—(a) miotic; (b) beta-blocker, epinephrine derivative, or both; and (c) systemic CAIs, if not contraindicated—must have been tested and continued unless found not to be effective, not accepted, or not tolerated by the patient.
• Patients met 1 of 9 specified combinations of criteria involving elevated IOP, VF loss, and damage to the optic nerve.
• BCVA of 20/80 or better.

Exclusion Criteria

Discernable congenital anomaly of the anterior chamber angle, eyes with secondary glaucoma, eyes with pigment dispersion, patients with exfoliative glaucoma, concurrent active disease in the study eye that may affect IOP or its measurement, patients on kidney dialysis, history of laser or incisional surgery in the eye considered for study (except laser iridotomy), laser retinal treatment anterior to the vortex vein ampullae, local retinal cryotherapy involving less than 2 quadrants for retinal holes anterior to the vortex vein ampullae, eyes that had undergone gonioplasty in more than 180 degrees of the anterior chamber angle circumference, eyes with proliferative or severe nonproliferative retinopathy, eyes with (dilated) pupil diameter of <2 mm, eyes with field loss attributed to a nonglaucoma condition, and the fellow eye previously enrolled in the Advanced Glaucoma Intervention Study.

Length of Follow-Up

8 to 13 years.

Funding

• Research to Prevent Blindness, Inc, New York, NY.
• National Eye Institute, National Institutes of Health.

Results

• IOP reduction was greatest in both Whites and Blacks with the TAT protocol.
• Visual function was better preserved in Blacks with the ATT protocol than the TAT sequence through 7 years of follow-up.
• Visual function was better preserved in Whites with the TAT protocol than the ATT sequence through 7 years of follow-up.
• IOP fluctuation was associated with VF progression at a follow-up of 7 years.
• Consistently low IOP is associated with reduced progression of VF (eyes that had IOP <18 mm Hg at 100% of visits had a mean IOP of 12.3 mm Hg).

Trabeculectomy increases the relative risk of cataract formation by 78%.

Implications

• ALT is preferable to trabeculectomy without antimetabolites in Blacks whose glaucoma is uncontrolled with medical therapy.
• Identifies the importance of IOP control in reducing the risk of glaucoma progression and the significance of IOP fluctuation as a risk factor for VF progression in patients with advanced open-angle glaucoma.

Notes

• Very few initial trabeculectomies used antimetabolites.
• The study findings may have been very different if antimetabolites had been routinely used in trabeculectomies.
• Prostaglandin analogues, topical CAIs, and topical selective alpha-2-adrenergic agonists were not commercially available early in the study.
• The increased risk of cataract after trabeculectomy likely contributed to the greater VA loss in the TAT sequence relative to the ATT sequence, especially in the early follow-up years.
• The race–treatment interactions are likely due to more scar tissue formation in Blacks after incisional glaucoma surgery without adjunctive antimetabolites, causing failure of their trabeculectomies, whereas Whites were less prone to this.

Collaborative Initial Glaucoma Treatment Study

Main Study Purpose

To compare the outcomes of initial management of OAG by using medical therapy versus trabeculectomy.

Location

United States.

Study Population

Newly diagnosed OAG (POAG, exfoliation syndrome glaucoma, and pigmentary glaucoma) patients.

Interventions the Participants Were Randomized to Receive

1. Initial medical therapy: When initial treatment failed, the following protocol was followed: ALT → trabeculectomy (with or without 5-FU) → medication → trabeculectomy with antimetabolite → medication → ophthalmologist’s discretion.
2. Initial trabeculectomy (with or without 5-FU): When initial treatment failed, the following protocol was followed: ALT → medication → trabeculectomy with antimetabolite → medication → ophthalmologist’s discretion.

Study Design

• Multicenter, randomized clinical trial.
• 607 patients (307 assigned to initial medical therapy and 300 assigned to initial trabeculectomy) were enrolled between 1993 and 1997.

Inclusion Criteria

• Age 25 to 75 years.
• Early Treatment Diabetic Retinopathy Study (ETDRS) VA better than or equal to 20/40 and 1 of the following:
  • IOP ≥ 20 mm Hg, HVF 24-2 result with ≥3 contiguous points on the total deviation plot at the <5% level and glaucoma hemifield test result that is “outside normal limits,” and optic disc compatible with glaucoma.
  • IOP between 20 to 26 mm Hg, HVF 24-2 result with ≥2 contiguous points on the total deviation plot at the <2% level and glaucoma-tous optic disc damage.
  • IOP ≥27 mm Hg and glaucomatous optic disc damage.

Exclusion Criteria

Prior use of any glaucoma medications for more than 14 days, use of glaucoma medications within 3 weeks of baseline visit, advanced VF loss at initial presentation, ocular disease that might affect measurement of IOP, VA or VF testing, diabetic retinopathy with >10 microaneurysms, previous ocular surgery, significant cataract, and use of corticosteroids (oral or ophthalmic).

Length of Follow-Up

7 to 10 years.

Funding

National Eye Institute, National Institutes of Health.

Results

• Both treatment arms showed significant reduction in IOP.
• Lower IOP in the trabeculectomy group as compared with the group assigned to pressure-lowering medications through 9 years of follow-up.
• No substantial difference in VF progression between the groups.
• Greater rate of cataract development in the trabeculectomy group.
• Quality-of-life indicators were similar except for increased local eye symptoms in the trabeculectomy group.
• Patients with more advanced VF loss at baseline fared better with initial trabeculectomy.
• Less optic disc progression in the surgery group.
• IOP reduction of 35% seems to stabilize glaucoma.
• Patients with diabetes experienced more VF loss over time if treated with initial trabeculectomy.
• There was no evidence of a substantial effect of trabeculectomy on the IOP of the untreated fellow eye during follow-up.
• Patients with an early post-trabeculectomy IOP spike had significantly higher mean IOP at years 3 and 5 of follow-up, but this was not associated with subsequent VF loss.
• IOP variation during treatment was associated with an increased risk of VF progression.

Implications

Suggests that trabeculectomy is a reasonable alternative to initial treat-ment with pressure-lowering medications in patients with newly diagnosed OAG.

Notes

No MMC was used (at least in the initial trabeculectomy).

Tube Versus Trabeculectomy Study

Purpose

To prospectively compare the safety and efficacy of trabeculectomy with adjunctive MMC as compared with implantation of a glaucoma drainage device (GDD; Baerveldt 350-mm²) in eyes that had previously undergone filtering surgery, cataract surgery with intraocular lens (IOL implantation, or both.

Location

United States and United Kingdom.

Study Population

Patients with uncontrolled glaucoma who had undergone previous trabeculectomy, cataract extraction with IOL, or both.

Interventions the Participants Were Randomized to Receive

1. Baerveldt 350-mm² glaucoma implant.
2. Trabeculectomy with MMC (0.4 mg/mL for 4 minutes).

Study Design

• Multicenter, randomized, clinical trial.
• 212 patients (107 assigned to the GDD group and 105 assigned to the trabeculectomy with MMC group) were enrolled between 1999 and 2004.

Inclusion Criteria

• Age 18 to 85 years.
• Inadequately controlled glaucoma with IOP ≥18 and ≤40 mm Hg on tolerated medical therapy.
• Previous trabeculectomy, cataract extraction with IOL implantation, or both.

Exclusion Criteria

Active iris neovascularization or active proliferative retinopathy, iridocorneal endothelial syndrome, aphakia, vitreous in the anterior cham-ber for which a vitrectomy is anticipated, chronic or recurrent uveitis, severe posterior blepharitis, unwilling to discontinue contact lens use after surgery, previous cyclodestructive procedure, scleral buckling procedure, silicone oil present, conjunctival scarring precluding a trabeculectomy superiorly, and need for glaucoma surgery combined with other ocular procedures (ie, cataract surgery, penetrating keratoplasty, or retinal surgery), or anticipated need for additional ocular surgery.

Length of Follow-Up

5 years.

Funding

• Pfizer, Inc, New York, New York.
• Abbott Medical Optics, Santa Ana, California (manufacturer of Baerveldt GDD).
• National Eye Institute, National Institutes of Health.
• Research to Prevent Blindness, Inc, New York, New York.

Results

• Both treatment groups had similar IOP reduction at 3 years of follow-up.^2,3
• Both treatment groups had similar use of supplemental medical therapy at 3 years of follow-up.
• Trabeculectomy group had a significantly higher failure rate* com-pared with the GDD group at 3 years of follow-up.
• Trabeculectomy group had significantly more postoperative complications than the GDD group (60% in the trabeculectomy group compared with 39% in the GDD group); however, the rate of serious complications** was similar in both groups.
• Reoperation rate for glaucoma was higher in the trabeculectomy group but this did not reach statistical significance.
• The GDD group was more likely to maintain IOP control and avoid persistent hypotony, loss of light perception, and reoperation for glaucoma than the trabeculectomy with MMC group during the first 3 years of follow-up. (*See definitions in notes section following.)

Implications

• Prior to the TVT Study, GDD surgery was often reserved for patients who had a high risk of failure from trabeculectomy (eg, patients with neovascular glaucoma) or who had multiple past trabeculectomies.
• This study supports use of GDDs as an alternative to trabeculectomy with MMC in glaucoma patients who have had prior incisional intraocular surgery.

Notes

• Fornix-based conjunctival flaps with a more diffuse application of MMC at a lower dosage has developed since the TVT study was initiated, which may affect outcomes and rates of complications.
• This study is sponsored, in part, by the company that makes the Baerveldt GDD.

* Failure = IOP >21 mm Hg or not reduced by 20% below baseline on 2 consecutive follow-up visits after 3 months, IOP ≤5 mm Hg on 2 consecutive follow-up visits after 3 months, reoperation for glaucoma (additional intervention that required a return to the operating room, cyclodestruction, vitreous biopsy with injection of intravitreal antibiotics), or loss of LP (light perception) vision. ** Serious complications = surgical complications that were associated with loss of 2 or more lines of Snellen VA and/or reoperation to man-age the complication.

Ahmed Baerveldt Comparison Study

Main Study Purpose

To compare the outcomes and complications of the Ahmed glaucoma valve (AGV) and the Baerveldt glaucoma implant (BGI) for surgical management of refractory glaucoma.

Location

• United States.
• London, England (Moorfields Eye Hospital).

Study Population

Refractory glaucomas (primary glaucomas with previous intraocular surgery, neovacular glaucoma, uveitic glaucoma, and other secondary glaucomas).

Interventions the Participants Were Randomized to Receive

1. Ahmed glaucoma valve model FP7.
2. Baerveldt glaucoma implant model 101-350.

Study Design

• Multicenter, randomized clinical trial.
• 276 patients (143 in the AGV group and 133 in the BGI group) were enrolled between 2006 and 2008.

Inclusion Criteria

• Patients 18 to 85 years of age with inadequately controlled glaucoma despite receiving maximum tolerated medical therapy, with IOP ≥18 mm Hg.
• Patients with refractory glaucoma and history of previously failed trabe­ culectomy or other intraocular surgery in the study eye were eligible.
• Patients without previous intraocular surgery were eligible if they had secondary glaucomas known to have a high failure rate with trabeculectomy such as neovascular, uveitic, or iridocorneal endothelial syndrome-associated glaucoma.

Exclusion Criteria

Patients who lacked light perception vision, patients who underwent a previous cyclodestructive procedure or previous aqueous shunt implanted in the same eye, patients who underwent a prior scleral buckling procedure or other external impediment to supratemporal drainage device implantation, patients who had presence of silicone oil, patients who had vitreous in the anterior chamber sufficient to require a vitrectomy, patients who had uveitis associated with a systemic condition, such as juvenile rheumatoid arthritis, patients who had nanophthalmos, and patients who had Sturge-Weber syndrome, other conditions associated with elevated episcleral venous pressure, or needed aqueous shunt surgery combined with other ocular procedures.

Length of Follow-Up

• Ongoing study: 1 year follow-up data on 92% of the AGV group and 88% of the BGI group.
• Study intends to continue following patients up to 1 year after surgery.

Funding

• National Eye Institute, National Institutes of Health.
• New World Medical, Rancho Cucamonga, California (company that manufactures the Ahmed GDD).
• Research to Prevent Blindness, Inc, New York, New York.

Results

Both surgical procedures produced a significant reduction in IOP (AVG group 31.2 ± 11.2 mm Hg preoperatively → 15.4 ± 5.5 mm Hg

postoperatively; BGI group 31.8 ± 12.5 mm Hg preoperatively → 13.2 ± 6.8 mm Hg postoperatively) at 1 year.

• Average IOP in the BGI group was 2.2 mm Hg lower at 1 year com-pared with the AVG group.
• Both surgical procedures produced a significant reduction (AVG group 3.4 ± 1.1 glaucoma medications → 1.8 ± 1.3; BGI group 3.5 ± 1.1 glaucoma medications → 1.5 ± 1.4) in the need for medical therapy at 1 year.
• Similar failure rates* between both treatment groups at 1 year.
• BGI group had more complete successes*.
• Higher rate of reoperation in the AGV group (8%) compared with the BGI group (1%) at 1 year.
• Decrease of 2 or more lines of Snellen VA in 32% of patients overall at 1 year, no difference between the 2 groups.
• More early (≤3 months) postoperative complications in the BGI group.
• Both groups had a similar rate of late postoperative complications at 1 year♦.

*See definitions in notes section below.

♦See implications section below.

Implications

• BGI may be a better option for patients with advanced glaucoma who require a very low postoperative IOP.
• For patients with little or no glaucomatous damage (just very elevated preoperative IOP), the Ahmed GDD is a reasonable option for stabilizing IOP.
• The BGI provided slightly better IOP lowering at 1 year and less need for reoperation for elevated IOP, but patients in the BGI group had more serious complications associated with reoperation, vision loss, or both.

Notes

• Failure = IOP >21 mm Hg or not reduced by 20% less than baseline or IOP ≤5 mm Hg (on 2 consecutive follow-up visits after 3 months), requiring additional glaucoma surgery, removal of the implant, or loss of light perception­ vision.
• Complete success = eyes that had not failed and were not receiving supplemental medical therapy.

Primary Tube Versus Trabeculectomy Study

Main Study Purpose

To compare the long-term safety and efficacy of the Baerveldt glaucoma implant versus trabeculectomy with MMC in patients who have not had prior intraocular surgery.

Location

United States.

Study Population

Patients with glaucoma.

Interventions the Participants Were Randomized to Receive

1. Trabeculectomy with MMC.
2. Baerveldt (350-mm²) glaucoma implant.

Study Design

• Multicenter, randomized, clinical trial.
• Aiming to enroll 88 patients to each arm (176 patients total).
• Ongoing study—plan to enroll patients from May 2008 through May 2012.

Inclusion Criteria

• Age 18 to 85 years.
• Glaucoma that is inadequately controlled on tolerated medical therapy with IOP ≥18 mm Hg and ≤40 mm Hg.
• No previous incisional ocular surgery (including keratorefractive surgery).

Exclusion Criteria

Active iris neovascularization or active proliferative retinopathy, iridocorneal endothelial syndrome, epithelial or fibrous ingrowth, chronic or recurrent uveitis, steroid-induced glaucoma, severe posterior blepharitis, unwilling to discontinue contact lens use after surgery, previous cyclode-structive procedure, conjunctival scarring from prior ocular trauma or cicatrizing disease precluding a superior trabeculectomy, functionally significant cataract, and need for glaucoma surgery combined with other ocular procedures or anticipated need for additional ocular surgery.

Length of Follow-Up

Ongoing study—plan to follow patients for 5 years.

Funding

• Abbott Medical Optics, Inc, Anta Ana, California.
• National Eye Institute, National Institutes of Health.
• Research to Prevent Blindness, Inc, New York, New York.

Results

Ongoing trial.