This study is a phase 3, randomized, multi-center study to evaluate the efficacy and safety of the NT-501 implants in participants with macular telangiectasia type 2.

Phase 3, prospective, multicenter, masked, sham-controlled study with the overall study objective to evaluate the efficacy and safety of NT-501 for the treatment of MacTel. Secondary objective was to evaluate the safety of NT-501 in participants with MacTel. This was a multicenter study conducted at 20 study centers in the United States, Australia, Germany, and the United Kingdom.

Key Inclusion Criteria:

1. Participant must have at least one study eye with a positive diagnosis of MacTel with evidence of fluorescein leakage typical of MacTel and at least one of the other features that include hyperpigmentation that is outside of a 500 micron radius from the center of the fovea, retinal opacification, crystalline deposits, right-angle vessels, or inner/outer lamellar cavities
2. Participant must have an Inner Segment - Outer Segment Junction Line (IS/OS) Photo Receptor (PR) break in the study eye(s) and en face EZ (area of IS/OS loss) as measured by spectral-domain optical coherence tomography (SD-OCT) between 0.16 mm^2 and 2.00 mm^2
3. Participant's best corrected visual acuity (BCVA) is a 54-letter score or better (20/80 or better) as measured by the Early Treatment Diabetic Retinopathy Study (ETDRS) chart at screening.
4. Participant must have steady fixation in the foveal or parafoveal area and sufficiently clear media for good quality photographs
5. Participant must be greater than 21 years of age or less than 80 years of age at screening
6. Participant must be able to provide written informed consent to participate in the study, in accordance with the International Conference on Harmonisation Good Clinical Practices guidelines, and local regulations, before initiating any study-related procedures
7. Women of childbearing potential must agree to use highly effective contraception (Germany and France only)

Key Exclusion Criteria:

1. Participant is medically unable to comply with study procedures or follow-up visits
2. Participant received intravitreal steroid therapy for non-neovascular MacTel within the last 3 months
3. Participant has ever received intravitreal anti-vascular endothelial growth factor (VEGF) therapy in the study eye OR has, within the past 3 months, received intravitreal anti-VEGF in the fellow eye at randomization
4. Participant has evidence of ocular disease other than MacTel that, in the judgment of the examining physician, may confound the diagnosis, procedures or outcome of the study (eg, glaucoma, severe nonproliferative or proliferative diabetic retinopathy, uveitis)
5. Participant has a chronic requirement (eg, ≥ 4 weeks at a time) for ocular medications and/or has a diagnosed disease that, in the judgment of the examining physician, may be vision threatening or may affect the primary outcome (artificial tears are permitted)
6. Participant has evidence of intraretinal neovascularization or subretinal neovascularization (SRNV), as evidenced by hemorrhage, hard exudate, subretinal fluid or intraretinal fluid in either eye
7. Participant has evidence of central serous chorio-retinopathy in either eye
8. Participant has evidence of pathologic myopia in either eye
9. Participant has significant corneal or media opacities in either eye
10. Participant has had a vitrectomy, penetrating keratoplasty, trabeculectomy, or trabeculoplasty
11. Participant has any of the following lens opacities: cortical opacity > standard 3, posterior subcapsular opacity > standard 2, or a nuclear opacity > standard 3 as measured on the Age-Related Eye Disease Study (AREDS) clinical lens grading system
12. Participant has undergone lens removal in the previous 3 months or YAG laser within 4 weeks
13. Participant was a participant in any other clinical trial of an intervention (drug or device) within the last 6 months
14. Participant is on chemotherapy
15. Participant is pregnant or breastfeeding
16. Participant has a history of malignancy that would compromise the 24-month study survival
17. Participant with a history of ocular herpes virus in either eye
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 evidence of intraretinal hyperreflectivity by OCT

The subjects and all personnel at the image reading center remained masked to the treatment assignment throughout the study. In addition, the refractionist, VA examiner, and photographers/imagers were masked to treatment assignment (NT-501 implantation or sham procedure) at all follow-up visits. The ophthalmologist, surgeon, and clinic coordinator were instructed not to discuss the assigned treatment with the subject.