The purpose of this study is to perform trabeculopuncture a test to determine the distal outflow tract function to predict the success of ab interno trabeculectomy.

The aim of this study is to develop a non-invasive predictive test for the function of the distal outflow tract after ab interno trabeculectomy for open angle glaucoma. We hypothesize that the ocular pressure drop and outflow change after preoperative trabeculectomy may predict the success of ab interno trabeculectomy. The results of this study should allow trabeculopuncture to be used to select the most appropriate procedure for the individual patient.

Inclusion Criteria:

• individuals ≥ 18 years of age
• clinical diagnosis of: primary open angle glaucoma, pigmentary glaucoma, or pseudoexfoliation glaucoma
• uncontrolled intraocular pressure (IOP) with maximally tolerated medical therapy
• progressive thinning of retinal nerve fiber layer assessed by Spectral domain optical coherence tomography (p < 0.05)
• progression of visual field defects
• visually significant cataract and indication to reduce IOP or glaucoma medication burden

Exclusion Criteria:

• clinical diagnosis of neovascular glaucoma, angle-closure glaucoma, uveitic glaucoma, neovascular glaucoma
• prior glaucoma surgery
• preexisting conditions affecting the episcleral venous pressure including Grave's ophthalmopathy, Sturge-Weber syndrome, Arteriovenous fistulas (carotid-cavernous fistula)