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PURPOSE To characterize features of glaucoma associated with a TANK binding kinase 1 (TBK1) gene duplication, which is among the most common molecularly defined causes of normal tension glaucoma (NTG). DESIGN Retrospective observational case series METHODS: We conducted a retrospective case series, by reviewing medical records of 7 members of a pedigree with normal tension glaucoma (NTG) caused by TBK1 gene duplications. Clinical features of these patients at diagnosis, throughout management, and at latest follow up were identified including age, intraocular pressure (IOP), central corneal thickness (CCT), optic nerve head appearance, and mean deviation (MD) assessed with Humphrey visual field (HVF) testing protocols. RESULTS At initial diagnosis, the mean age was 35 ± 7 years, IOP was 16 ± 2.1 mm Hg, cup-to-disc (C/D) ratio was 0.9 ± 0.08, and MD assessed via HVF 30-2 and/or 24-2 testing protocols was -9.0 ± 8.9 (range: -1.8 to -27) dB in the 14 study eyes. At initial diagnosis, 4 (28%) of 14 eyes had no visual field defect, 4 (28%) had early visual field defects, and 6 (43%) had severe visual field defects. Patients had a mean follow-up of 21.5 ± 9.0 years and experienced an average reduction of IOP by 28%. Four of 12 eyes (33%) had stable visual fields throughout follow-up, while 8 eyes (67%) had slow to moderate progression. The 30-2 and/or 24-2 HVF tests had an average change in MD of -0.53 ± 0.26 dB/year. No eyes had rapid progression with a MD > 1.0 dB/year. At final follow up, the mean IOP was 11.5 ± 2.9, and C/D ratio was 0.94 ± 0.4. At final follow up, 3 (21%) of 14 eyes had early visual field defects, 4 (29%) of 14 eyes had moderate visual field defects, and 7 (50%) had severe visual field defects. Six (43%) of 14 eyes met criteria for legal blindness. CONCLUSIONS We provide the first report of the clinical features and long-term clinical course in a family of NTG patients with TBK1 gene duplications. TBK1-associated glaucoma exhibits classic features of NTG. Patients present with severe disease at a relatively early age and most (67%) have slow to moderate progression of their visual field fields. The rate of visual field change appears correlated with the magnitude of IOP, suggesting that it may be advantageous to set extremely low IOP targets for some patients with TBK1-associated glaucoma.