The Effect of Topical Brimonidine on the Ocular Hemodynamics in Patients of POAG Using OCTA
Condition: Glaucoma, Primary Open Angle; Ocular Blood Flow; Optical Coherence Tomography Angiography
MeSH terms: Glaucoma; Glaucoma, Open-Angle
Study type: Interventional
Phase: Phase 4

Summary: 
      Topical Brimonidine is a well-established topical antigalucoma, ocular hypotensive
      therapeutic that has been in use since 1996. Brimonidine stands out among other topical
      ocular hypotensives in that it has a neuroprotective effect that is independent of IOP
      reduction. This has been demonstrated in multiple animal and human controlled studies both in
      vivo and in vitro. The mechanisms proposed so far to account for this neuroprotection focus
      mainly on molecular level antiapoptotic effects and modulation of some excitatory stimuli
      like glutamate. In this study we try to test the hypothesis that a positive hemodynamic
      profile of Brimonidine on ocular blood flow may be responsible at least in part for its
      unique neuroprotective effects.
    

Detailed description: 
      -  Study Design: A prospective, longitudinal, interventional, uncontrolled study

        -  Participants: primary open angle glaucoma patients recruited during the period of study
           from the fayoum university hospital ophthalmic outpatient clinic.

        -  Methods:

      Primary open angle glaucoma patients that are Brimonidine naiive and at the same time either
      medication naiive or have been on a fixed antiglaucoma medication for at least a month prior
      will be commenced on Brimonidine 0.2% bid with prior baseline imaging by OCT angiography
      (Optovue) of macula 6*6 mm and ONH 4.5*4.5 mm. After commencing Brimonidine patients will be
      followed up by OCT angiography at three visits assigned for 1,2,3 months after commencing
      Brimonidine. Every time the patient is imaged by OCT, imaging is done twice, once in a seated
      position at presentation and another- also in a seated position-, but after a protocol of
      right recumbency for 30 minutes in order to produce a postural position change as a vascular
      stress test to assess autoregulatory capacity of ocular and systemic circulation.

      At each visit, IOP and arterial blood pressure are measured both in the seated position and
      after the 30-minute recumbency protocol in order to mathematically calculate the mean ocular
      perfusion pressure that will be correlated with OCT angiography data including vascular
      density, as well as indirect parameters of blood flow.

      Data will be statistically analysed using the SPSS software.
    

Intervention name(s): Brimonidine tartrate 0.2% ophthalmic solution
Intervention type(s): Drug
Intervention description(s): Topical Brimonidine tartrate 0.2% bid ophthalmic solution. A selective alpha 2 adrenergic agonist with ocular hypotensive and neuroprotective properties used in glaucoma and ocular hypertension.
Intervention MeSH terms: Brimonidine Tartrate; Ophthalmic Solutions
Intervention model: Single Group Assignment
Intervention model description: A longitudinal, prospective, interventional, uncontrolled study
Masking: None (Open Label)
Primary purpose: Treatment