Clinical trial NCT01535768: Effect of Prophylactic Aqueous Suppression on Hyperencapsulation of Ahmed Glaucoma Valves
Official title: Effect of Prophylactic Aqueous Suppression on Hyperencapsulation of Ahmed Glaucoma Valves
Study type: INTERVENTIONAL
Overall status: UNKNOWN
Phase: PHASE4
Conditions: Glaucoma
Lead sponsor: Credit Valley EyeCare
Sponsor class: INDUSTRY
Collaborators: name: Canadian Glaucoma Clinical Research Council
First posted: 2012-02-20
Enrollment: 150
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: PARALLEL
Primary purpose: TREATMENT

Brief summary: After implantation of an Ahmed glaucoma valve in patients with glaucoma, hyperencapsulation phase is an unwanted postoperative phenomenon, typically occurring with the free 3 months postoperatively. When this does occur, it is treated with aqueous suppressant eye drops.

This study aims to determine if it is possible to reduce the rate of hyperencapsulation phase. Patients in the treatment group will receive aqueous suppressant eye drops before the hyperencapsulation phase starts. Treatment will be initiated once their intraocular pressure is above a pre-defined level, and will target a pre-defined range.

Detailed description: Patients with glaucoma requiring tube shunt surgery, with or without simultaneous cataract surgery, will be enrolled in this prospective randomized controlled study at ten sites across Canada and the United States (to be determined). Patients with highly advanced glaucoma at high risk of fixation loss, neovascular glaucoma, chronic uveitis, marked corneal disease, sulfa allergy, renal disease or any contraindication to diamox use will be excluded.

Patients scheduled for Ahmed glaucoma valve surgery, with or without cataract surgery, will be randomized using a stratified central block randomization approach to the treatment group or control group. Those scheduled for combined cataract and tube shunt will be randomized separately from those receiving tube shunt alone. Surgeons will be masked to the postoperative treatment or control group at the time of surgery since randomization will occur when the patient is one-week postoperative Those in the treatment group would receive short-term prophylactic aqueous suppression for the first 3 postoperative months to maintain intraocular pressure (IOP) between 7 and 10mmHg. The control group would not receive prophylactic aqueous suppression, but would be treated using a similar protocol as the treatment group in the event that an Hyperencapsulation phase (HEP) endpoint is met.

Prophylactic aqueous suppression in the study group would only be given for the 1st 3 months postoperatively. At the 3 month visit, aqueous suppression will be stopped. The primary outcome measure is washout IOP at 4 months postoperative. Washout IOP will be checked one month after discontinuation (earlier if needed i.e., advanced glaucoma patients).

Beyond 3 months, aqueous suppressants would be used at the clinician's discretion based on IOP.

At the conclusion of the study, the 4-month postoperative washout IOP, the incidence of HEP, the 12-month IOP, the 13-month washout IOP, and medication requirement would be compared between the treatment and control arms.

Eligibility criteria: Inclusion Criteria:

* clinical diagnosis of glaucoma
* scheduled for Ahmed glaucoma valve surgery, with or without simultaneous cataract surgery

Exclusion Criteria:

* neovascular glaucoma
* uveitic glaucoma
* prior tube shunt surgery
* prior cyclodestruction procedure
* abnormal cornea that would make IOP measurements unreliable
* sulfa allergy
* systemic contraindication to acetazolamide use
* inability to attend follow up visits
* intraocular pressure greater than 21 at postoperative week 1 (represents primary failure of the valve)
* anterior chamber fill within the first week postoperatively

Primary outcomes:
measure: Intraocular pressure
timeFrame: 4 months postoperative
Secondary outcomes:
measure: Hyperencapsulation phase (HEP)
timeFrame: first 3 months postoperative
measure: Qualified Ahmed Glaucoma Valve success
timeFrame: 12 months
measure: Absolute Ahmed Glaucoma Valve success
timeFrame: 13 months
measure: Number of glaucoma medications
timeFrame: 12 months
Other outcomes:
Locations:
city: Mississauga
country: Canada
facility: Credit Valley Eye Care
state: Ontario
Study officials:
affiliation: University of Toronto
name: Devesh K Varma, MD FRCSC
role: PRINCIPAL_INVESTIGATOR
affiliation: University of Toronto
name: Ike K Ahmed, MD FRCSC
role: PRINCIPAL_INVESTIGATOR
affiliation: University of Toronto
name: Amandeep S Rai, MD
role: STUDY_DIRECTOR
References: