Visual and structural prognosis of the untreated fellow eyes of unilateral normal tension glaucoma patients

Purpose To investigate the visual and structural prognosis of untreated initial non-glaucomatous fellow eyes of unilateral normal tension glaucoma (NTG) patients. Methods In this retrospective observational cohort study, 50 NTG patients with unilateral visual field (VF) loss and no VF defect, retinal nerve fiber layer (RNFL) defect or neuroretinal rim (NRR) notching in the fellow eyes, and those who had initial non-glaucomatous fellow eyes untreated were included. For the fellow eyes, the development of VF defect, RNFL defect, and NRR notching was inspected retrospectively by two observers. Baseline clinical characteristics including initial intraocular pressure (IOP), central corneal thickness, and spherical equivalent (SE) were compared between glaucomatous and fellow eyes. Results During the mean follow-up period of 8.77 ± 2.92 years, five patients (10 %) developed RNFL defect and four patients (8 %) developed NRR notching in the fellow eye. Among six patients (12 %) who had developed either RNFL defect or NRR notching, only three patients (6 %) developed VF loss in 1.81, 3.09, and 9.27 years respectively. The initial IOP was significantly higher ( p = 0.031), SE was more myopic ( p = 0.025), and the occurrence of disc hemorrhage ( p = 0.049) was significantly higher in glaucomatous eyes than that in fellow eyes. Conclusions The incidence of glaucoma development in the fellow eye is rather low. Therefore, the initial non-glaucomatous fellow eye of the unilateral NTG patient may be observed without treatment until glaucoma develops.