Ahmed Versus Baerveldt Comparison (ABC) Study

The recruitment status of this study is unknown because the information has not been verified recently.
Verified February 2009 by University of Miami.
Recruitment status was  Active, not recruiting
Sponsor:
Collaborators:
Research to Prevent Blindness
Information provided by:
University of Miami
ClinicalTrials.gov Identifier:
NCT00376363
First received: September 13, 2006
Last updated: February 12, 2009
Last verified: February 2009
  Purpose

The objective of this study is to compare the long-term safety and efficacy of the Ahmed and the Baerveldt implants in patients who are undergoing aqueous shunt implant surgery for glaucoma. Eligible patients will be randomized. Outcome measures include intraocular pressure, visual acuity, visual field, number of glaucoma medications, glaucoma reoperations, and complications, including suprachoroidal hemorrhage, endophthalmitis, choroidal effusion, diplopia, corneal edema, and shunt/tube erosion.


Condition Intervention Phase
Glaucoma
Device: Ahmed implant
Device: Baerveldt implant
Phase 3

Study Type: Interventional
Study Design: Allocation: Randomized
Endpoint Classification: Safety/Efficacy Study
Intervention Model: Parallel Assignment
Masking: Open Label
Primary Purpose: Treatment
Official Title: Ahmed Versus Baerveldt Comparison (ABC) Study

Resource links provided by NLM:


Further study details as provided by University of Miami:

Primary Outcome Measures:
  • intraocular pressure [ Time Frame: 5 years ] [ Designated as safety issue: Yes ]
  • reoperation for glaucoma [ Time Frame: 5 years ] [ Designated as safety issue: No ]
  • number of glaucoma medications [ Time Frame: 5 years ] [ Designated as safety issue: No ]
  • reoperation for ocular complication [ Time Frame: 5 years ] [ Designated as safety issue: Yes ]
  • diplopia [ Time Frame: 5 years ] [ Designated as safety issue: Yes ]

Secondary Outcome Measures:
  • visual acuity [ Time Frame: 5 years ] [ Designated as safety issue: Yes ]
  • visual field [ Time Frame: 5 years ] [ Designated as safety issue: Yes ]
  • endophthalmitis [ Time Frame: 5 years ] [ Designated as safety issue: Yes ]
  • suprachoroidal hemorrhage [ Time Frame: 5 years ] [ Designated as safety issue: Yes ]
  • choroidal effusion [ Time Frame: 5 years ] [ Designated as safety issue: Yes ]
  • corneal edema [ Time Frame: 5 years ] [ Designated as safety issue: Yes ]
  • shunt/tube erosion [ Time Frame: 5 years ] [ Designated as safety issue: Yes ]

Enrollment: 276
Study Start Date: November 2005
Estimated Study Completion Date: December 2013
Estimated Primary Completion Date: December 2013 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: Ahmed implant,1
Ahmed glaucoma drainage implant for intraocular pressure control
Device: Ahmed implant
placement of glaucoma drainage device to control intraocular pressure
Other Name: Ahmed fp7
Active Comparator: Baerveldt implant
Baerveldt glaucoma drainage implant for intraocular pressure control
Device: Baerveldt implant
placement of glaucoma drainage device to control intraocular press
Other Name: Baerveldt 350

  Hide Detailed Description

Detailed Description:

Background and Significance

Aqueous shunt devices have traditionally been reserved for treatment of only the most refractory glaucomas. However, more recent studies have reported favorable results in comparison with trabeculectomy in medically uncontrolled glaucomas at lower risk of filtration failure. Consequently, aqueous shunt devices have been used increasingly in glaucoma drainage surgery.

There are two principal designs of implant in common use, the Ahmed glaucoma valve implant (New World Medical, Los Ranchos, CA, USA and the Baerveldt implant (Advanced Medical Optics, Santa Ana, CA, USA).

Having both evolved from the Molteno, the Ahmed and Baerveldt devices have in common a tube portion that drains aqueous humor from the anterior chamber to a plate that is implanted on the equatorial sclera. The size of plate determines the surface area of the drainage bleb.

The Ahmed and Baerveldt implants differ in two major respects. Firstly, the plate surface area of the Baerveldt 350 implant is almost double that of the Ahmed (185 mm2). Secondly, the Ahmed has a flow-restrictor that limits early hypotony without the need for additional external ligation.

We propose a randomized prospective clinical trial comparing the long-term safety and efficacy of the Ahmed glaucoma valve implant (FP-7) with the 350-mm2 Baerveldt implant (101-350) for surgical control of secondary glaucoma and primary glaucoma in eyes that have undergone previous ocular surgery.

Objective

The objective of this study is to compare the long-term safety and efficacy of the Ahmed FP-7 implant and the 350-mm2 Baerveldt implant in patients who are undergoing aqueous shunt implant surgery. Patients who qualify for the study are randomized to receive either an Ahmed FP-7 or Baerveldt BG-101-350 implant.

Outcome discrimination between the two treatment groups will be made using typical measures of visual function (visual acuity and visual field), intraocular pressure, number of glaucoma medications, and glaucoma reoperations. Emphasis will also be placed on complication rates, including suprachoroidal hemorrhage, endophthalmitis, choroidal effusion, diplopia, corneal edema, and shunt/tube erosion.

Assignment

Since the purpose of this study is to compare the safety and efficacy of two surgical procedures used in the management of glaucoma, randomization techniques are used to assure an unbiased treatment assignment to patients.

Stratification:

Patients will be stratified by clinical center. At each Clinical Center, half of the patients will receive an Ahmed and half will receive a Baerveldt implant . Randomization takes place at the time the patient is enrolled in the study after informed consent is obtained.

Randomization:

A permuted variable block randomization scheme stratified by clinical center and type of glaucoma will be performed.

The following scenarios will constitute a failure in the ABC Study for the purposes of survival analysis:

  • IOP > 21mmHG or < 6mmHg on 2 consecutive study visits at visits > 3 months
  • IOP reduced by < 20% on 2 consecutive study visits at visits > 3 months
  • Reoperation for glaucoma
  • Loss of light perception vision
  • Removal of implant for any reason

Clinical Procedures

Visual Acuity

Visual acuity is an important outcome variable in the ABC Study. Visual acuity is measured before pupil dilation, tonometry, gonioscopy, or any other technique that could affect vision. Refraction is performed prior to formal measurement of visual acuity by either technique at the Qualifying Assessment and at the annual follow-up visits. Snellen visual acuity is measured at the Qualifying Assessment and at every follow-up visit.

Subjective refraction must be performed at the Qualifying Assessment and at the annual follow-up visits in order to determine best-corrected visual acuity. It is permissible to use a phoropter or trial frame to determine best-corrected Snellen visual acuity.

Slit Lamp Biomicroscopy

Examination of the anterior segment using slit lamp biomicroscopy is performed at the Qualifying Assessment to document the preoperative status of the eye, and at all follow-up examinations to detect any changes in ocular status during the course of the study which may be attributable to the disease or treatment. Slit lamp biomicroscopy may be performed with any commercially available instrument, and it is used in a standard fashion starting anteriorly and working posteriorly. Standardizing subjective grading of lenticular opacities is difficult, if not impossible. However, it is expected that subjective grading by each investigator is relatively reproducible. Attempts will be made to compare subjective gradings between investigators.

Conjunctiva:

Eyes are examined carefully for tube or shunt erosion.

Cornea:

The cornea is examined at high magnification to evaluate the epithelium, stroma, and endothelium. The techniques of diffuse illumination, scleral scatter, and retroillumination may be used. Findings consistent with a diagnosis of the iridocorneal endothelial (ICE) syndrome, epithelial downgrowth, or fibrous downgrowth make the eye ineligible for the study. The presence of corneal epithelial or stromal edema is noted. Eyes are examined for the presence of tube-cornea touch.

An assessment is made of the position and length of the tube in the eye.

Anterior Chamber:

Before fluorescein instillation or pupillary dilation, the degree of anterior chamber cell and flare is determined. Eyes with vitreous in the anterior chamber are ineligible for the study if it is anticipated that a vitrectomy will be needed at the time of glaucoma surgery. Careful assessment of the anterior chamber depth is made postoperatively. If the anterior chamber is shallow, the central anterior chamber depth is measured relative to the corneal thickness. The appropriate gradation of > 3 CT, > 2 CT, > 1 CT, < 1 CT, or lens-cornea touch is documented.

Iris:

Before pupillary dilation, the pupillary iris is examined at high magnification for the presence of neovascularization. If rubeosis iridis is present, this should be documented.

Lens:

After pupillary dilation, the investigator assesses the lens and grades any cataract present as mild, moderate, or severe. In pseudophakic eyes, the presence of a posterior chamber or anterior chamber intraocular lens is documented. Aphakic eyes are excluded from the study.

Tonometry

Goldmann applanation tonometry is used to measure the intraocular pressure, except when irregular corneal astigmatism, corneal scarring, or corneal edema precludes accurate readings. In these cases, the Tono-Pen (Mentor) is used. The intraocular pressure is measured prior to pupillary dilation. Whenever possible, the intraocular pressure should be checked at the same time of the day as the Qualifying Assessment to minimize the effect of diurnal fluctuation The Tono-Pen (Mentor) is used in cases of corneal edema, corneal scarring, or irregular corneal astigmatism. The Tono-Pen probe tip is covered with a new Ocu-Film Tip Cover. The instrument is calibrated immediately prior to use, as described in the Mentor Tono-Pen Instruction Manual. The right eye is always tested first. A drop of 0.5% proparacaine is instilled. The patient is positioned in the sitting position and instructed to fix on a distant object. Tight-fitting neckwear is loosened, and the patient is instructed not to hold his or her breath. The Tono-Pen is activated by depressing the activation switch momentarily. The Tono-Pen is brought in contact with the patient's cornea lightly and briefly while holding the instrument perpendicular to the cornea. A click will sound and a digital intraocular pressure measurement will be displayed each time a valid reading is obtained. After four valid readings, a final beep sounds and the averaged measurement appears on the display, along with a single line denoting statistical reliability. Measurements are repeated until two successive readings are obtained within 1 mm Hg and both have a statistical reliability of 5%, indicating that the standard deviation of the valid measurements is 5% or less of the number displayed. The investigator records the last two successive measurements. After testing of the right eye is complete, the same technique is applied to testing of the left eye.

Pachymetry

Aqueous shunt implantation has been implicated in long-term damage to the cornea. In this study the position of the tube will be documented in relation to the cornea and the central corneal thickness monitored throughout the study.

Central corneal thickness will be measured in each eye, by ultrasound pachymetry. A minimum of 5 measurements will be taken and the lowest recorded.

Motility Evaluation

Diplopia is an important complication which may occur following glaucoma drainage implantation. The incidence of permanent restrictive strabismus associated with glaucoma drainage implantation is not precisely known, as this complication has not been studied prospectively. In order to address this issue, a formal motility evaluation is performed in all patients preoperatively and in those patients with diplopia at the 6 month follow-up visit or beyond. In addition, all patients will undergo a motility evaluation at the 1 year and 5 year follow-up visits. Transient diplopia following glaucoma drainage implantation is not uncommon. This study will focus on the incidence and nature of permanent restrictive strabismus associated with the glaucoma drainage implantation.

The cover-uncover and alternate cover tests are performed with the patient looking in primary gaze, as well as in upgaze, downgaze, left gaze, and right gaze. Motility evaluation is performed with the patient looking in the distance.

Any heterophorias or heterotropias are identified, and the deviation is measured with hand-held prisms. In patients who are unable to fixate for cover testing, the deviation may be measured by centering the corneal light reflexes with prism using the modified Krimsky method.

An estimate of restriction of abduction, adduction, elevation and depression of each eye is made using a 0 - 4 empirical grading scale.

Gonioscopy

Gonioscopy is performed with the patient sitting at the slit lamp using either a Zeiss type four-mirror gonioprism or Goldmann single- or three-mirror lens. A preoperative examination of the anterior chamber angle is essential to document neovascularization and peripheral anterior synechiae, to identify the presence of silicone oil in the angle and to identify an appropriate implantation site for the tube.

Ophthalmoscopy

A dilated fundus examination is performed at the Qualifying Assessment to determine the preoperative status of the eye, and at all postoperative follow-up examinations to detect any changes in ocular status produced by the disease or treatment. After pupil dilation with appropriate mydriatics, the optic nerve and posterior pole are examined at the slit lamp using a Hruby lens, fundus contact lens, or Volk 90 diopter, 78 diopter, or 60 diopter lens. A head-mounted indirect ophthalmoscope and hand held condensing lens (20 diopter or 28 diopter Nikon aspheric lens) is used to evaluate the retinal periphery.

At the Qualifying Assessment, particular attention is paid for signs of proliferative retinopathy, including retinal neovascularization, neovascularization of the disc, vitreous hemorrhage, or preretinal hemorrhage. At all postoperative follow-up visits, ophthalmoscopy is performed to evaluate for posterior segment complications, such as serous choroidal effusions, suprachoroidal hemorrhage, or hypotony maculopathy.

Perimetry

Visual field assessment is an important outcome measure in the ABC Study. Quantitative automated perimetry is performed using the Humphrey Field Analyzer. Visual field testing is performed before tonometry, gonioscopy, or any other technique that could affect vision. A visual field should be attempted in any eye that has sufficient vision to permit finger counting at two feet. Eyes with poor central vision may have an intact, off-center island of vision which may be measured with perimetry.

For the ABC Study, a 24-2 threshold test is performed in all patients using a size III white stimulus. Visual field testing may be performed with the Swedish Interactive Thresholding Algorithm (SITA) or full threshold strategy, but the same testing strategy must be used throughout the duration of the study. The pupil diameter should be 3 mm or greater before visual field testing is undertaken, and this may require pharmacologic dilation. Standardized refraction is performed to determine the patient's distance refraction and best-corrected visual acuity prior to visual field testing. The age appropriate plus lens is added to the distance refraction. Patient education is provided, and the instrument is set up for the test. The technician should monitor the patient during testing. Visual fields are performed preoperatively (within one month of enrollment in the study) and annually thereafter. Copies of all visual fields are faxed to the Statistical Coordinating Center for evaluation.

Surgical Procedures

Anesthesia:

The type of anesthesia is at the surgeon's discretion.

Conjunctival Flap:

An Ahmed FP-7 is used in all cases and implantation is performed in the superotemporal quadrant. A limbus-based or fornix-based conjunctival flap may be used depending on the surgeon's preference. Sufficient exposure is obtained in the superotemporal quadrant to permit placement of the Ahmed plate. A corneal traction suture or episcleral traction suture may be used to rotate the globe inferonasally to improve exposure.

Priming the Implant

A 28- or 30- gauge cannula is used to prime the Ahmed valve. Occlusion of the tube with a ligature is not permitted.

Attachment of Episcleral Plate:

The Ahmed plate is sutured to the sclera at a measured distance of 8 - 10 mm posterior to the limbus using the two fixation holes on the plate. The type of nonabsorbable suture used is of the surgeon's choice.

Preparation of Tube:

The tube is trimmed bevel-up to extend 2 to 3 mm into the anterior chamber.

Insertion of Tube into the Anterior Chamber:

A 23-gauge needle is used to enter the anterior chamber at the posterior limbus parallel to the iris plane. The Ahmed tube is inserted through this entry incision and should be well positioned in the anterior chamber away from the corneal endothelium and just above the iris. A 23-gauge needle produces an adequate entry incision for the tube without causing aqueous leakage around the tube.

Coverage of Tube:

A donor patch graft composed of donor sclera, donor cornea, or pericardium is used to cover the limbal portion of the tube. The suture selected to fixate the patch graft is of the surgeon's choice.

Conjunctival Closure:

Tenon's and conjunctiva are reapproximated to the limbus. The suture used for the conjunctival closure is determined by the surgeon in keeping with his or her usual practice.

Optional Viscoelastic Insertion

At the surgeons discretion, a viscoelastic of his or her choice may be inserted into the anterior chamber, especially if the anterior chamber shallows after balanced salt solution is inserted.

Intraoperative Medications:

The use of intraoperative medications is at the surgeon's discretion. Subconjunctival antibiotics and corticosteroids may be injected, and a cycloplegic-mydriatic drop and steroid-antibiotic ointment may be instilled at the conclusion of the case, as determined by the surgeon in keeping with his or her usual practice.

Baerveldt Implantation

Anesthesia:

The type of anesthesia is at the surgeon's discretion.

Conjunctival Flap:

A 350-mm2 Baerveldt is used in all cases and implantation is performed in the superotemporal quadrant. A limbus-based or fornix-based conjunctival flap may be used depending on the surgeon's preference.

Scleral Exposure:

Sufficient exposure is obtained in the superotemporal quadrant to permit placement of the Baerveldt plate. A corneal traction suture or episcleral traction suture may be used to rotate the globe inferonasally and improve exposure.

Insertion of Episcleral Plate:

The 350-mm2 Baerveldt plate may be positioned under or over the superior rectus and lateral rectus muscles, depending on the surgeon's usual practice. The implant is sutured to the sclera at a measured distance of 8 - 10 mm posterior to the limbus using the two fixation holes on the plate. The type of nonabsorbable suture used is of the surgeon's choice.

Occlusion of Tube:

The Baerveldt tube must be completely occluded in all cases in order to restrict aqueous flow to the plate until it becomes encapsulated. This is done to minimize the incidence of postoperative hypotony. The method of tube occlusion is left to the discretion of the surgeon. Ligation of the tube with a polyglactin suture near the tube-plate junction, ligation with a polypropylene suture which is inserted into the anterior chamber with the tube, or internal occlusion of the tube using a "rip-cord" technique have all been used effectively. A 30-gauge cannula is used to cannulate the end of the tube and confirm complete occlusion of the tube. Following tube occlusion, the surgeon may fenestrate the tube if desired. The method of tube fenestration is left to the discretion of the surgeon.

Preparation of Tube:

The tube is trimmed bevel-up to extend 2 to 3 mm into the anterior chamber.

Insertion of Tube into the Anterior Chamber:

A 23-gauge needle is used to enter the anterior chamber at the posterior limbus parallel to the iris plane. The Baerveldt tube is inserted through this entry incision and should be well positioned in the anterior chamber away from the corneal endothelium and just above the iris. A 23-gauge needle produces an adequate entry incision for the tube without causing aqueous leakage around the tube.

Coverage of Tube:

A donor patch graft composed of donor sclera, dura mater, or pericardium is used to cover the limbal portion of the tube. The suture selected to fixate the patch graft is of the surgeon's choice.

Conjunctival Closure:

Tenon's and conjunctiva are reapproximated to the limbus. The suture used for the conjunctival closure is determined by the surgeon in keeping with his or her usual practice.

Intraoperative Medications:

The use of intraoperative medications is at the surgeon's discretion. Subconjunctival antibiotics and corticosteroids may be injected, and a cycloplegic-mydriatic drop and steroid-antibiotic ointment may be instilled at the conclusion of the case, as determined by the surgeon in keeping with his or her usual practice.

Study Organization

Introduction

Multicenter clinical trials require an organizational structure that provides efficient operations and facilitates communication. The following resource centers work together in this study:

  • Clinical Centers (CC)
  • Statistical Coordinating Center (SCC)
  • Safety and Data Monitoring Committee (SDMC)
  • Steering Committee (SC)

Clinical Centers:

Each Clinical Center is responsible for screening potential study patients, enrolling an adequate number of eligible patients, and following the patients according to the protocol until the termination of the study. Each CC has one principal investigator. The responsibilities of the Clinical Centers are as follows:

  • To assess the eligibility of patients for the ABC Study.
  • To enroll an adequate number of patients in the study through informed consent.
  • To manage each patient in accordance with the randomized assignment provided by the SCC.
  • To examine patients using the techniques and schedules established for the study.
  • To complete the proper forms and obtain visual fields and quality of life assessments at the appropriate follow-up visits.
  • To respond promptly to requests made by the SCC.
  • To maintain patient records for the ABC Study in an easily accessible and confidential manner.
  • To obtain approval for the study and consent form from the local Institutional Review Board.
  • To promote patient satisfaction and commitment to the trial.
  • To provide representation at all meetings of the SC.

Statistical Coordinating Center

The Statistical Coordinating Center is located at the Department of Biostatistics at the Bascom Palmer Eye Institute. The SCC receives, edits, processes, analyzes, and stores all study data. The SCC coordinates the activities at the Clinical Centers and monitors adherence to the study protocol. The responsibilities of the SCC are listed below:

  • To provide guidance in the development and implementation of the design of the primary study and ancillary studies.
  • To confirm local IRB approval of the study and consent form before initiating participation of a CC.
  • To verify eligibility of the patient and completion of the consent form prior to randomization.
  • To randomize study patients.
  • To review data received, process, and store all study data.
  • To produce extensive monitoring reports for the SC and SDMC every six months and upon request.
  • To assist in the preparation of manuscripts.

Safety and Data Monitoring Committee

The Safety and Data Monitoring Committee is responsible for the ethical conduct of the study. This committee oversees the informed consent process and major changes in the protocol. The SDMC reviews the accumulating data for evidence of adverse and beneficial treatment effects. This committee meets twice each year for the duration of the study. Telephone conferences will occur as needed. The responsibilities of the SDMC are as follows:

  • To review the study design and study documents before the start of the study to identify any problems that may affect future data analysis or patient safety.
  • To monitor adherence to the study protocol at each CC.
  • To review treatment reports prepared by the SCC for evidence of adverse and beneficial treatment effects.
  • To terminate the study if treatment benefits or treatment risks are so high for one treatment group that continuation of the trial is deemed unethical.
  • To advise the SC on interpretation of study data.
  • To recommend to the SC changes in study protocol based on periodic data analysis.
  • To review and approve all publications and presentations.
  • To determine when data collected in the study should be released to study investigators, study patients, the medical community, and the public.

Steering Committee

The Steering Committee is composed of the principal investigator from each Clinical Center. The SC provides leadership for the trial. This committee has overall responsibility for directing activities and formulating policy for the study. This committee meets twice each year for the duration of the study. Telephone conferences will occur as needed. The specific functions of the SC are as follows:

  • To evaluate and approve operational procedures in the study, including the Manual of Procedures and data forms.
  • To change procedures and resolve technical issues during the course of the trial.
  • To review study progress and take steps to correct deficiencies, such as patient recruitment, adherence to protocol, or data collection procedures.
  • To appoint and disband subcommittees needed for execution of the study.
  • To review and approve ancillary studies.
  • To collaborate in preparing manuscripts of study findings for publication.
  • To review and approve all publications and presentations.

Policy Matters

The Ahmed vs. Baerveldt Comparison (ABC) Study requires that written consent be obtained from each patient enrolled in the study. The patient is requested to sign the consent form only after patient education is completed. The signed consent form is kept with the study records at the Clinical Center. A copy of the signed consent is given to the patient, and a second copy is sent to the Statistical Coordinating Center.

The principal investigator of each Clinical Center is responsible for obtaining approval for the study and consent form from the local Institutional Review Board. A copy of each Clinical Center's approved consent and documentation of IRB approval must be submitted to the Statistical Coordinating Center prior to beginning patient enrollment in the study. A copy of the consent form approved by the Institutional Review Board for the University of Miami School of Medicine and the Western IRB is provided in the investigator pack.

Policy of Confidentiality

Materials distributed for Steering Committee and Safety and Data Monitoring Committee meetings are confidential. Minutes from all study meetings are confidential. Access to a participant's record by any unauthorized individual is prohibited. Tabulations or listings which reveal the identity of individual study participants are confidential.

Clinical Center Procedures

Qualifying Assessment

The Qualifying Assessment establishes whether the patient satisfies ABC Study eligibility criteria. If the patient appears to be eligible for the study, the Clinical Center completes the Qualifying Assessment Form and Preoperative Form. Both forms are faxed to the Statistical Coordinating Center, along with a copy of the consent form. Informed consent is an eligibility criterion because it is an agreement by the patient to be randomized and complete follow-up in their treatment group. The SCC reviews each of the inclusion and exclusion criteria to ensure that the patient is eligible. It is vital to the scientific validity of the study that every eligible patient be offered enrollment.

Assignment of Patient Identification Number

Any patient who is confirmed by the Statistical Coordinating Center to meet the eligibility criteria and is enrolled in the study is assigned a patient identification number. The SCC provides a list of patient identification numbers to each Clinical Center. The patient identification number is a six digit, three letter code which is unique for each patient.

Randomization Procedure

Randomization takes place at the time the patient is enrolled in the study. After patient eligibility is confirmed and a patient identification number is provided, the Statistical Coordinating Center assigns treatment by saying, "Ahmed implant" or "Baerveldt implant". The Clinical Center then repeats the assigned treatment. The surgery date is the study entry date, and the dates for all postoperative follow-up visits are computed from this date.

The randomization schedule is constructed using a computer pseudo-random number generator. The allocation ratio is equal between the two treatment groups. The randomization is blocked by clinic and study stratum using a variable block design. This procedure ensures that there is an equal number of patients in each treatment group even early in the trial, and that the CC is not able to predict the next treatment assignment.

Schedule of Visits

All study investigators must be familiar with the schedule of visits to ensure that required data is collected and that future visits are scheduled within the appropriate time windows. The need for continued follow-up and timely visits should be stressed to the patient during the informed consent process and throughout the study. An appointment schedule is generated for each patient by the Statistical Coordinating Center and sent to the patient's Clinical Center. Time windows for follow-up visits are shown in Table 1. Table 2 summarizes the required data at each of the scheduled visits.

Statistical Coordinating Center Procedures

A master log is kept of each patient randomized in the ABC Study. An appointment schedule is made for each patient and sent to the patient's Clinical Center. When a data form is received at the Statistical Coordinating Center, it is processed for filing and data entry. Each form is data entered by a data entry clerk and then verified by double entry by the SCC Research Coordinator. Edit checks, such as missing data and out-of-range values, will be clarified within the CC.

The statistical package SPSS is used for data entry, management, and analysis. Each of the study's two statisticians has a personal computer and one more is dedicated to data entry. The Research Coordinator also has a personal computer to use for data management, study correspondence, reports, and manuscripts. Each computer, except the one dedicated to data entry, has access to the University of Miami's network for e-mail, Internet access, and data file transfer.

Data Security

The paper data forms for the ABC Study are kept in file cabinets in the Biostatistics facility in the McKnight Research Building. The building is locked and access is by card key entry. A security guard is present during working hours. The computer files for the study are kept on computers in the same location. These rooms are kept locked when not in use, and the study computer files are password-protected. The data is backed up weekly, and monthly backups are stored at a remote facility. Computer data files used for publication are saved and stored as separate files.

Data Forms

The data forms were designed to be self-explanatory. Their completion should not require reference to separate information manuals. The data forms contain information to be collected at a given point in time during the study. Information collected at another date is incorporated into a separate form. Data forms are faxed to the Statistical Coordinating Center for data entry. Forms will be reviewed periodically and revised as dictated by protocol changes. The various data forms are provided at the end of this section.

  Eligibility

Ages Eligible for Study:   18 Years to 85 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No
Criteria

Inclusion Criteria:

  • Age 18 to 85 years, inclusive.
  • Glaucoma that is inadequately controlled on tolerated medical therapy with intraocular pressure greater than or equal to 18 mm Hg.
  • Glaucoma drainage implant as planned surgical procedure.
  • POAG with previous failed trabeculectomy or other intraocular surgery.
  • Secondary glaucoma with or without previous intraocular surgery

Exclusion Criteria:

  • Unwilling or unable to give consent or unwilling to accept randomization.
  • Patient out of area and potentially unavailable for follow-up visits
  • No light perception.
  • Uveitis secondary to Juvenile Idiopathic Arthritis
  • Previous cyclodestructive procedure or previous aqueous shunt device implanted in the same eye.
  • Supero-temporal buckling or other external impediment to supero-temporal aqueous shunt implantation.
  • Silicone oil-filled eyes or sufficient residual intraocular silicone oil to preclude supero-temporal aqueous shunt implantation.
  • Vitreous sufficient to require a vitrectomy present in the anterior chamber at the time of surgery.
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00376363

Locations
United States, Florida
University of Miami, Bascom Palmer Eye Institute
Miami, Florida, United States, 33136
Sponsors and Collaborators
University of Miami
Research to Prevent Blindness
Investigators
Principal Investigator: Donald L Budenz, M.D.,M.P.H. University of Miami
Principal Investigator: Keith Barton, M.D. Moorfields Eye Hospital NHS Foundation Trust
Principal Investigator: William J Feuer, M.S. University of Miami
  More Information

Publications:
Responsible Party: Donald L Budenz MD MPH, University of Miami
ClinicalTrials.gov Identifier: NCT00376363     History of Changes
Other Study ID Numbers: 2005-1738, NEI grant EY014801
Study First Received: September 13, 2006
Last Updated: February 12, 2009
Health Authority: United States: Institutional Review Board

Keywords provided by University of Miami:
glaucoma
Ahmed implant
Baerveldt implant

Additional relevant MeSH terms:
Glaucoma
Ocular Hypertension
Eye Diseases

ClinicalTrials.gov processed this record on September 22, 2014