The purpose of this global, multicenter, open-label, Phase 4 clinical extension study is to evaluate the long-term safety and efficacy of revakinagene taroretcel-lwey (Encelto™; hereinafter referred to as NT-501), in participants with macular telangiectasia type 2 (MacTel) who previously received the intraocular implant in a Phase 1, Phase 2, or Phase 3 clinical study. In addition, this study will evaluate the safety and efficacy of NT501 in participants who previously underwent the sham procedure in a Phase 3 MacTel clinical study and elect to have NT-501 implanted intraocularly in this Phase 4 study.

This extension study consists of 3 arms:

• Arm 1 (Phase 3 Treated Participants' Long-term Follow-up): Arm 1 is to assess the long-term safety and efficacy of NT-501 in participants who received NT-501 in a previous MacTel Phase 3 clinical study (NTMT-03-A or NTMT-03-B).
• Arm 2 (Phase 1 and Phase 2 Long-term Follow-up): Similar to Arm 1, Arm 2 is to assess the long-term safety of NT-501 in participants who received NT-501 in a previous MacTel Phase 1 or Phase 2 clinical study (NTMT-01, NTMT-02, or NTMT-01/02E).
• Arm 3 (Phase 3 Sham to Implant Crossover): Arm 3 will evaluate the safety and efficacy of NT-501 in participants who previously underwent the sham procedure in a Phase 3 MacTel clinical study (NTMT-03-A or NTMT-03-B) and elect to have NT-501 implanted intraocularly in this extension study.

Arms 1 and 2 are noninterventional and observational studies. Participants who received NT-501 in both eyes (ie, participated in study NTMT-02B) will be enrolled in either Arm 1 or Arm 2 based on the study in which the first NT-501 was implanted (ie, participants who received the first implant in a Phase 3 study will be enrolled in Arm 1 and those who received the first implant in the Phase 1 study or Phase 2 study will be enrolled in Arm 2).

Only Arm 3 is an interventional study where participants will receive an NT-501 implant. A participant can receive NT-501 in either eye that meets eligibility criteria according to investigator assessment, and in accordance with participant choice.

Inclusion Criteria

To be eligible to participate in this study, an individual participant must meet all the following criteria:

1. Male or female adult participants who previously completed an NT-501 MacTel clinical study and:

   1. Arm 1: received NT-501 intraocular implant in either Phase 3 study (NTMT-03-A or NTMT-03-B)

   2. Arm 2: received NT-501 intraocular implant in the Phase 1 study (NTMT-01), Phase 2 study (NTMT-02), or in the substudy of the Phase 1 and Phase 2 extension study (NTMT-01/02E)

      Note: participants who received NT-501 in both eyes (ie, participated in study NTMT-02B) will be enrolled in either Arm 1 or Arm 2 based on the study in which the first NT 501 was implanted (ie, participants who received the first implant in a Phase 3 study will be enrolled in Arm 1 and those who received the first implant in the Phase 1 study or Phase 2 study will be enrolled in Arm 2).

   3. Arm 3: underwent the sham procedure in either Phase 3 study (NTMT-03-A or NTMT-03-B)

2. Participants must have steady fixation in the foveal or parafoveal area and sufficiently clear media for good quality retinal imaging.

3. Participant or their legally authorized representative must be able to provide written informed consent to participate in the study, in accordance with the International Conference on Harmonisation (ICH) Good Clinical Practice (GCP) guidelines, and local regulations, before initiating any clinical study related procedures.

4. Arm 3: female participants of childbearing potential must agree to use highly effective contraception. Highly effective forms of contraception (generally a first-year typical use pregnancy risk of 1% or less) include the following: contraceptive implants; an intrauterine device; permanent contraceptive procedures (vasectomy, bilateral salpingectomy, bilateral tubal occlusion, or partial salpingectomy); abstinence. A combination of male condom with either cap, diaphragm, or sponge with spermicide (ie, double barrier methods) is also considered an acceptable, but not highly effective, method of birth control.

Note: Participants enrolled at investigator sites in France or Germany must agree to use 2 forms of contraception listed above during study participation.

Exclusion Criteria

To participate in this study, the potential participant must not meet any of the following criteria. (Note that the ocular exclusion criteria are relevant to the study eye[s], unless indicated for both eyes):

Exclusion Criteria Applicable to Arms 1, 2, and 3:

1. Participant is medically unable to comply with clinical study procedures or visits.

2. 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.

   Exclusion Criteria Applicable to Arm 3 Only:

3. Participant has significant corneal or media opacities in the study eye to be implanted.

4. Participant has evidence of pathologic myopia in the study eye to be implanted.

5. Participant has any of the following lens opacities in the study eye to be implanted: 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. Note: the participant can be reconsidered for enrollment 90 days after undergoing cataract surgery.

6. Participant has undergone lens removal in the study eye to be implanted in the previous 3 months or YAG laser within 4 weeks of the screening/baseline visit.

7. Participant has evidence of ocular disease in the study eye to be implanted 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).

8. Received intravitreal steroid therapy in the study eye to be implanted within the last year.

9. Received intravitreal anti-vascular endothelial growth factor therapy in the study eye to be implanted within the last 6 months.

10. Evidence of active exudative intraretinal neovascularization or subretinal neovascularization in the study eye to be implanted, as evidenced by hemorrhage, hard exudate, subretinal fluid, or intraretinal fluid.

11. Evidence of central serous chorioretinopathy in the study eye to be implanted.

12. Participant underwent vitrectomy, penetrating keratoplasty, trabeculectomy, or trabeculoplasty in the study eye to be implanted.

13. A history of ocular herpes virus in the study eye to be implanted.

14. Participant is on chemotherapy.

15. Participant is pregnant or breastfeeding.

16. Participation in any other clinical study of an intervention (drug or device) within 6 months prior to the screening/baseline visit.

17. A history of malignancy that would compromise survival during the clinical study.