A Randomized Study Comparing the Safety and Efficacy of the InnFocus MicroShunt® Glaucoma Drainage System to Standard Trabeculectomy In Subjects with Primary Open Angle Glaucoma

1. Male or female patient, age 40 to 85 years, inclusive
2. Early to severe primary open angle glaucoma where the mean diurnal intraocular pressure is not controlled on maximum tolerated medical therapy with intraocular pressure >= 15 mm Hg and <= 40 mm Hg while on glaucoma medications. Maximum tolerated medical therapy is defined as:
a. Three or more classes of topical glaucoma medications (prostaglandin analog, beta-adrenergic antagonist, carbonic anhydrase inhibitor, alpha-adrenergic agonist, parasympathomimetic). Combination glaucoma medications that consist of two or more glaucoma drugs will have each glaucomadrug component counted as a separate drug.
b. fewer than three classes presently in use if a subject*s intolerance to specific glaucoma medications and ineffective medications are included.
3. Primary open angle glaucoma diagnosis based on:
a. visual field mean deviation of -3dB or worse and
b. glaucomatous optic nerve damage as evidenced by any of the following optic disc or retinal nerve fiber layer structural abnormalities documented on slit lamp stereo biomicroscopy or in stereo disc photos:
* Diffuse thinning, focal narrowing, or notching of the optic disc rim, especially at the inferior or superior poles
* Localized abnormalities of the peripapillary retinal nerve fiber layer, especially at the inferior or superior poles
* Optic disc neural rim asymmetry of the two eyes consistent with loss of neural tissue
* Disc rim or peripapillary retinal nerve fiber layer hemorrhages.
4. Prior ab interno conjunctival-sparing glaucoma procedures were conducted more than 6 months prior to enrolment (e.g., iStent, Trabectome, gonioscopy-assisted transluminal trabeculectomy [GATT]).
5. Patient must have signed and dated the Informed Consent form.
6. Patient is willing to attend follow-up visits for two years postoperatively.

1. Patient unwilling or unable to give informed consent, unwilling to accept randomization, or unable to return for scheduled protocol visits through 2 years.
2. Patient < 40 years or >85 years of age.
3. Patient is pregnant or nursing or unable to use appropriate birth control.
4. Vision level of no light perception.
5. Active iris neovascularization, active proliferative retinopathy or other ophthalmic disease that could confound study results.
6. Iridocorneal endothelial syndrome.
7. Epithelial or fibrous downgrowth.
8. Secondary glaucoma such as post-trauma, pseudoexfoliation or pigment dispersion.
9. Chronic ocular inflammatory disease.
10. Subject already enrolled in this or another study (only one eye can participate in this study) or completed their participation in another study within 30 calendar days of the screening exam.
11. Aphakia.
12. Vitreous in the anterior chamber.
13. A history of corneal surgery (including Lasik or PRK), corneal opacities or disease/pathology if accurate IOP measurement may be affected. (Active corneal infection or Fuchs dystrophy are examples.)
14. Severe anterior or posterior blepharitis.
15. Unwilling to discontinue contact lens use after surgery for the duration of the study.
16. Previous incisional ophthalmic surgery involving the conjunctiva.
17. Prior clear corneal cataract, angle or trabecular meshwork surgery conducted within the past 6 months (e.g., iStent, Trabectome, gonioscopy-assisted transluminal trabeculotomy)
18. Presence of an anterior chamber IOL (ACIOL).
19. Prior laser peripheral iridotomy conducted within three months of enrollment.
20. Need for glaucoma surgery combined with other ocular procedures or anticipated need for additional ocular surgery during the investigational period.
21. Fellow eye with poorer than 20/80 best-corrected visual acuity (BCVA) or points in both hemifields within 5 degrees of fixation with sensitivity less than <0 dB.
22. Known allergy or other contraindication to mitomycin C (MMC) drug.
23. Angle closure glaucoma or narrow anatomical chamber angle as identified by gonioscopy and classified as Shaffer Grade 0 or 1.
24. Endothelial cell density at screening for the central reading of the following values:
- Phakic
* Age 40-45< 2200 cells/mm2
* Age 46-55 < 2000 cells/mm2
* Age 56-65 < 1800 cells/mm2
* Age over 65 < 1600 cells/mm2
- Pseudophakic
* Age 40-45 < 1980 cells/mm2
* Age 46-55 < 1800 cells/mm2
* Age 56-65 < 1620 cells/mm2
* Age over 65 < 1440 cells/mm2
25. Any condition that prevents the investigational device implantation or trabeculectomy in the superior region of the study eye (e.g., peripheral anterior synechiae, scleral staphyloma or conjunctival scarring).
26. Diagnosed degenerative visual disorders not associated with existing glaucoma condition (e.g., advanced dry or wet macular degeneration or other retinal disorders, central retinal artery or vein occlusion) or choroidopathy (e.g., choroidal detachment, effusion, choroiditis, or neovascularization).
27. Central corneal thickness that is less than 450 microns or greater than 620 microns.
28. Previous cyclodestructive procedure
29. Prior retinal laser procedure conducted for any purpose other than treatment of retinal tear or hole.
30. Conditions associated with elevated episcleral venous pressure such as active thyroid orbitopathy, cavernous sinus fistula, Sturge-Weber syndrome, orbital tumors, orbital congestive disease.
31. Clinically significant sequelae from trauma (e.g., chemical burns, blunt trauma, etc.)
32. Ocular pathology or medical condition for which, in the investigator's judgment, the following factors would either place the subject at increased risk of complications or contraindicate device implantation or interfere with compliance to elements of the study protocol (e.g., ophthalmic examinations, follow-up visits),
a. inability to reliably complete visual field testing over the course of the study,
b. uncontrolled systemic disease (e.g. diabetes, hypertension) that could compromise their participation in the study.
c. Disorders that pose a fall risk, as well as compromise ability to take a visual field exam and take glaucoma medications (e.g., Parkinson's disease),
d. inability to discontinue use of blood thinners.
e. immunodeficiency concerns.
f. known corticosteroid responders whose pressure increases would not allow them to withstand the postop corticosteroid regimen.
33. Intraocular silicone oil.
34. Ocular steroid use in the planned study eye or systemic steroid use anytime within three months of the procedure. (This would not include the use of inhaled or dermatologic steroids.)
35. Completion of chemotherapy within six months of the screening visit.
36. Use of oral hypotensive glaucoma medications for treatment of fellow eye.
37. A requirement of general anesthesia for the procedure.
38. ALT/SLT within 90 days of enrollment.