This is a randomized, sham controlled, masked clinical trial of 60 study participants with glaucoma. Participants with a qualifying study eye will be randomized after screening and baseline evaluations to receive the NT-501 encapsulated cell therapy (ECT) implant or a sham surgery (control arm), and no explant will be required.

An examination for safety will occur one day and one week following implant and periodically thereafter for 24 months post-implant. Based on the primary analysis of data at 6 months, patients in the control arm may be offered the NT-501 ECT implant at the 12 month time point.

Inclusion Criteria:

Patients must meet all of the following criteria to join the study (all eligibility criteria must be met at the screening and baseline visits unless otherwise noted):

1. Participant must be medically able to undergo the testing required in the schedule of events (SOE).

2. Participant's clinical diagnosis must be consistent with glaucoma 1. characterized by the following features:

   a) Clinical evidence of progressive retinal ganglion cell (RGC) dysfunction and degeneration using both visual field and at least one structural modality as established by: i. Glaucomatous visual field abnormality. ii. Mean deviation (MD) of -3 to -15 dB. iii. Minimum average retinal nerve fiber layer (RNFL) thickness of 60 μm and maximum average RNFL of 90 μm.

   b) Residual visual field preservation including best-corrected visual acuity (BCVA) better than 20/200 in both eyes.

   c) Two visual field tests of adequate quality with a maximum visual field index (VFI) variability of ± 10%.

3. Participant's glaucoma must be clinically stable, with intraocular pressure (IOP) < 21.

4. If a participant has two eyes meeting study criteria, only the worse eye as determined by visual field index (VFI) will be deemed includable. If both eyes qualify and have the same VFI, a randomization procedure will assign one eye to the study.

5. Participant must understand and sign the informed consent. If the participant's vision is impaired to the point where he/she cannot read the informed consent document, the document will be read to the participant in its entirety.

6. Females of childbearing potential must agree to use an effective form of birth control.

7. Participant must be determined by the presurgical anesthesia or medical team to be fit for ophthalmic surgery for the NT-501 ECT implant insertion.

Exclusion Criteria:

1. Participant is unable to comply with study procedures or follow-up visits.
2. Participant has other optic nerve or retinal degenerative disease causing vision loss, irrespective of whether it is currently treated or untreated.
3. Participant has visual loss to less than 20/200 in non-study eye.
4. Participant is likely to be offered glaucoma surgery within 6 months of screening.
5. Participant has optic nerve atrophy beyond modest pallor.
6. Participant has cataract-associated vision loss to less than 20/40.
7. Participant has a history of ocular herpes zoster.
8. Participant has a requirement of acyclovir and/or related products during study duration. To be eligible for this study, the participant must discontinue use of these products prior to enrollment and must not continue with the products until after they have completed the study.
9. Participant has evidence of corneal opacification or lack of optical clarity.
10. Participant has uveitis or other ocular inflammatory disease.
11. Participant is receiving systemic steroids or other immunosuppressive medications.
12. Participant has diabetic macular edema and/or diabetic retinopathy.
13. Participant has myopic degeneration.
14. Participant is currently participating in or has within the last 3 months participated in any other clinical trial of a drug by ocular or systemic administration.
15. Participant is pregnant or lactating.
16. Participant is on chemotherapy.
17. Participant has a history of malignancy other than basal cell carcinoma, unless it was treated successfully 2 years prior to inclusion in the trial.
18. Participant has, in the opinion of the investigator, any physical or mental condition that would increase the risk of participation in the study or may interfere with the study procedures, evaluations and outcome assessments.
19. Participant has choroidal neovascularization secondary to age related macular degeneration or any other type of retinal degeneration that may interfere with the study procedures, evaluations and outcome assessments.
20. Any intraocular surgery of the study eye within 12 weeks prior to the screening visit
21. History of use of drugs with known retinal toxicity, at retinotoxic doses.
22. Participant has a history or current non-arteritic anterior ischemic neuropathy (NAION)
23. Patient has a history of multiple sclerosis.
24. Participant has glaucoma that is not considered open angle glaucoma, pseudoexfoliation glaucoma or pigmentary glaucoma..