Objective: The objective of this study is to investigate the effect of the ciliary neurotrophic factor (CNTF)-secreting NT-501 device on change from baseline in the area of macular ellipsoid zone disruption as measured by en face imaging by spectral domain optical coherence tomography (SD-OCT) in eyes with evidence of macular telangiectasia (MacTel) type 2 at 24 months. Study Population: Sixty-eight (68) participants with MacTel type 2 will be enrolled study wide. Up to 10 participants will be enrolled at NEI. Five participants will be included in the primary analysis; up to an additional five participants may be enrolled to account for participants who do not meet the eligibility criteria. Eligible participants will be adults, ages 21 to 80 years, who at the time of the screening visit have at least one study eye with a positive diagnosis of MacTel Type 2 with evidence of fluorescein leakage typical of MacTel or at least one of the other features including retinal opacification, crystalline deposits, right angle vessels, inner/outer lamellar cavities or hyperpigmentation not involving the center of the fovea, but no evidence of intraretinal/subretinal neovascularization. Participants must also have the presence of an IS/OS PR break in the study eye(s) and en face ellipsoid zone as measured by SDOCT between 0.16 mm2 and 4.00 mm2. Design: This is a Phase 2, prospective, multi-center, single-masked, sham-controlled study. All participants will have a screening period of up to 14 days. Surgery with the NT-501 implant or a sham procedure will occur within seven weeks after completing screening. Both eyes of the participants may be included in the study if eligible. Participants with one study eye that meets the inclusion criteria will be randomized (1:1) to receive the NT-501 implant or sham procedure in the study-eligible eye. If both eyes are eligible, then the right eye will be randomized (1:1) to receive the NT-501 implant or sham procedure. The left eye will receive the alternative surgery/sham. Study eyes will receive the NT-501 implant or sham procedure on Day 0 and will be assessed on Day 1, Week 1 ( 2 days), Month 1 ( 1 week), Month 3 ( 1 week), Month 6 ( 2 weeks), Month 12 ( 2 weeks), Month 18 ( 2 weeks) and Month 24 ( 2 weeks). Outcome Measures: The primary outcome will be change in the ellipsoid zone (area of IS/OS loss) (month 24 baseline) as measured by en face imaging by SDOCT in study eye(s). Secondary outcomes to investigate the efficacy of Ciliary Neurotrophic Factor (CNTF) produced by NT-501 include (all changes relative to baseline measurements): change in the ellipsoid zone (area of IS/OS loss) from baseline to Month 12; change in retinal sensitivity (dB) as measured by microperimetry from baseline to Months 12 and 24; proportion of study eyes with a 35% or more increase from baseline in the ellipsoid zone (area of IS/OS loss) at Months 12 and 24; change in best corrected visual acuity (BCVA) from baseline to Months 12 and 24; proportion of study eyes with 15 or more letter loss from baseline in BCVA at Months 12 and 24; proportion of study eyes with 10 or more letter loss from baseline in BCVA at Months 12 and 24; change in reading speed from baseline to Months 12 and 24. Exploratory outcomes to investigate the efficacy of Ciliary Neurotrophic Factor (CNTF) produced by NT-501 include (all changes relative to baseline measurements): change in cone density as measured by AOSLO from baseline to Months 12 and 24, in selected participants; change in NEI VFQ (overall and subscale) from baseline to Months 12 and 24; electroretinogram (ERG) changes from baseline to Months 6, 12 and 24, in selected clinics. Safety will be assessed by pre-specified safety outcomes as defined in the protocol. We initiated this study at the NEI in fiscal year 2014. In fiscal year 2015, the trial met its accrual goal of six (6) participants, and enrollment in the study was closed. In fiscal year 2017, participants reached the primary endpoint of the trial at 2 years, and analysis of results is in progress.
