Phacoemulsification Versus Phacoemulsification With Micro-bypass Stent
Condition: Primary Angle-Closure Glaucoma; Primary Angle Closure Without Glaucoma Damage
MeSH terms: Glaucoma; Glaucoma, Angle-Closure
Study type: Interventional

Summary: 
      Assessing the safety and efficacy of a micro-bypass stent in combination with cataract
      surgery in subjects with primary angle closure. Subjects are randomized into two arms:
      phacoemulsification cataract surgery alone versus phacoemulsification cataract surgery
      combined with the micro-bypass stent implantation. Post surgery intraocular eye pressure will
      be recorded to assess the efficacy of both arms.
    

Detailed description: 
      Aim: To assess the safety and efficacy of the iStent trabecular micro-bypass stent (Glaukos
      Corporation, Laguna Hills, CA) in combination with cataract surgery in subjects with primary
      angle closure and mild to moderate primary angle closure glaucoma

      Method: Prospective, randomised controlled trial, blinded to patient and intra-ocular
      pressure measuring staff. 32 patients, 1:1 ratio, in 2 arms of phacoemulsification alone
      compared to phacoemulsification with iStent.

      Hypothesis: Phacoemulsification with micro-bypass stent has a better intraocular pressure
      (IOP) lowering effect compared to phacoemulsification alone in primary angle closure and
      primary angle closure glaucoma at 1 year after surgery.

      Importance: Primary angle closure and primary angle closure glaucoma are conventionally
      treated with eye drops that lower the intraocular pressure (IOP). Phacoemulsification/lens
      extraction can often help lower the eye pressure by widening the drainage angle and via
      ultrasound mechanisms, however, in some cases the IOP is not lowered, or even can cause the
      IOP to be higher. The iStent implant can be used together with phacoemulsification to lower
      the IOP and in Primary open angle glaucoma, it gives an additional 20% IOP reduction. It is
      unclear what effect the iStent has in primary angle closure or primary angle closure glaucoma
      as it has never been studied. It is important because primary angle closure glaucoma is much
      more common in the Singaporean Chinese population and the iStent can potentially be used to
      control the IOP instead of conventional eye drops and glaucoma surgery which have their own
      potential adverse effects.

      Potential Benefits: iStent with phacoemulsification may control the IOP better than
      phacoemulsification alone, reduce the need for IOP lowering medication after surgery, and
      prevent the need for glaucoma surgery in the future.

      Potential Risks: The iStent has risks of IOP spikes, bleeding in the anterior chamber and
      iStent dislocation.Phacoemulsification has the risks of: infection, bleeding, reduced vision,
      inflammation, posterior capsular rupture, vitreous loss, retinal detachment, endophthalmitis,
      suprachoroidal haemorrhage and Intraocular Lens dislocation.
    

Intervention name(s): iStent implantation
Intervention type(s): Device
Intervention description(s): The iStent is a FDA and Health Sciences Authority (HSA) approved micro-bypass stent device that bypasses the trabecular meshwork (filtration membrane of the aqueous fluid exit pathway) and reroutes aqueous from the anterior chamber directly into canal of Schlemm and out of the eye. It lowers the intraocular pressure (IOP) by increasing the outflow of fluid from the eye from the micro-bypass. In angle closure, the lens has to be removed to create enough space for the iStent to be inserted.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Single centre, randomised prospective trial, the patient and the intraocular pressure (IOP)checking staff will be blinded. Randomised by random envelope shuffle technique.
1:1 ratio allocation 2 arms: phacoemulsification alone and phacoemulsification and iStent. 16 patients in each arm, 32 patients in total. The post-operative management is the same for both arms After operation the patient will be followed up at day 1, week 1, week 2, months 1, 3, 6 and 12.
At each visit the patient will have the following tests: Tonometry (IOP check) - Not to be taken by the operating surgeon, to be taken by 2 people, one IOP checker and one reader.
Masking: Double (Participant, Outcomes Assessor)
Primary purpose: Treatment
Keywords: istent; primary angle closure