Earlier Intraocular Pressure Control After Ahmed Glaucoma Valve Implantation for Glaucoma

Overview

The purpose of this study is to compare the occurrence rate of the high pressure phase and the final pressure outcomes between patients treated with glaucoma medication prior to the expected onset of the high pressure phase to those patients who have glaucoma medication started at the onset of the high pressure phase. The investigators hypothesize that if glaucoma medications are started prior to the expected onset of high pressure phase, the high pressure phase will not occur as frequently and the ultimate pressure level will be lower than if the glaucoma medications are started at the onset of this phase.

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Treatment
    • Masking: None (Open Label)
  • Study Primary Completion Date: March 2013

Detailed Description

Tube shunt procedures are a popular surgery for the control of glaucoma. Tube shunt devices are designed to drain eye fluid (aqueous humor) through a tube inserted into the front chamber of the eye (anterior chamber) to a plate secured to the mid-posterior section of the outer eyeball wall. The body then lays down collagen tissue and forms a capsule around the plate. The fluid filters through the capsule of collagen tissue and is reabsorbed into the ocular and systemic circulation. The collagen tissue continues to remodel itself over a long period of time (up to years). However, a well characterized, yet poorly understood, phenomenon occurs in many patients in the 4-8 weeks after the device's implantation, called the hypertensive phase. The pressure of the eye can increase from a desirable level of about 10 immediately after the tube shunt implantation to much higher levels, in the range of 20 to 30's, and then it may gradually return to less than 20. Such a high pressure phase can cause irreversible damage an eye with glaucoma. The usual management of a high pressure phase is to start glaucoma medications as soon as it is detected. A previous study we conducted showed that this high pressure phase resolves in about half of patients with medical therapy, but the other half may continue to have higher than expected pressures. The exact cause of this high pressure phase is unknown. However, it is postulated that the mechanism may involve a compaction collagen tissue layers under the eye's own fluid pressure while the collagen tissue is being laid down, which in turn creates a firm, dense capsule that makes escape of fluid difficult. Therefore, it is argued that if the formation of eye fluid is reduced by medication during this initial period when the collagen tissue is laid down, the compaction of collagen, and subsequently the high pressure phase may be avoided. The purpose of this study is to compare the occurrence rate of the high pressure phase and the final pressure outcomes between patients treated with glaucoma medication prior to the expected onset of the high pressure phase to those patients who have glaucoma medication started at the onset of the high pressure phase. We hypothesize that if glaucoma medications are started prior to the expected onset of high pressure phase, the high pressure phase will not occur as frequently and the ultimate pressure level will be lower than if the glaucoma medications are started at the onset of this phase. We believe that this study will have a very significant impact on the management of glaucoma with tube shut procedures. If it is true that the rate and pressure level of the hypertensive phase can be reduced by simply starting glaucoma medications to reduce the formation of eye fluid before the expected the high pressure phase begins, which is generally 4 weeks after implantation of the tube shunt device, glaucoma patients can be saved from exposure to the very high level of eye pressure, and the eventual pressure control may be better.

Interventions

  • Drug: glaucoma medications (Timolol, Brimonidine, Dorzolamide, Brinzolamide)
    • Subjects may receive glaucoma medications after Ahmed valve implantation

Arms, Groups and Cohorts

  • Experimental: Research arm (postop IOP>10)
    • Receive glaucoma medications if the eye pressure more than 10 mmHg after AHmed valve implantation
  • Active Comparator: Standard of care arm (postop IOP>17)
    • Receive glaucoma medication if eye pressure more than 17 mmHg after Ahmed valve implantation

Clinical Trial Outcome Measures

Primary Measures

  • Rate of Hypertensive Phase After Ahmed Valve Implantation for Glaucoma
    • Time Frame: within 6 months after surgery
    • Intraocular pressure more than 21 mmHg during the first 6 months after Ahmed valve implantation after the pressure has been reduced to less than 22 mmHg in the first postoperative week
  • Intraocular Pressure Control After Ahmed Valve Implantation for Glaucoma
    • Time Frame: 3 weeks after surgery
    • intraocular pressure comparison between groups after the Ahmed valve implantation
  • Intraocular Pressure of Eyes With Hypertensive Phase Versus Without Hypertensive Phase
    • Time Frame: 1 year after surgery
    • intraocular pressure of eyes with hypertensive phase versus without hypertensive phase

Participating in This Clinical Trial

Inclusion Criteria

1. Patients requiring Ahmed glaucoma valve implantation to control intraocular pressure between the ages of 18 and 85 years. Exclusion Criteria:

1. Unwilling or unable to give consent or unwilling to accept randomization. 2. Patient out of area and potentially unavailable for follow-up visits. 3. Known allergic reaction to timolol, brimonidine, dorzolamide, brinzolamide, or sulfa drugs. 4. Known medical contraindications to the use of beta-blockers, including congestive heart failure, heart block, asthma, and chronic obstructive pulmonary disease. 5. Concurrent intraocular procedure with Ahmed glaucoma valve implantation 6. Previous Ahmed glaucoma valve implantation

Gender Eligibility: All

Minimum Age: 18 Years

Maximum Age: 85 Years

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • University of California, Los Angeles
  • Provider of Information About this Clinical Study
    • Principal Investigator: Simon Law, Clinical Associate Professor of Health Sciences – University of California, Los Angeles
  • Overall Official(s)
    • Simon K Law, MD, Principal Investigator, Jules Stein Eye Institute, University of California Los Angeles

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