Purpose To investigate whether quantitative optical coherence tomography angiography (OCTA) metrics of the superficial/deep macular retina are associated with the development of visual field (VF) loss in the fellow eyes of normal tension glaucoma (NTG) patients with unilateral VF loss.

Methods A longitudinal study was conducted in which 61 eyes with normal VF (mean VF mean deviation −0.7±1.6 dB) from 61 NTG patients were included. All subjects underwent OCTA imaging, spectral-domain-OCT imaging and VF testing. OCTA metrics of superficial capillary plexus and deep capillary plexus (DCP) in the macular region were measured. Relationships between baseline OCTA metrics, demographics and ocular characteristics and the risk of VF glaucoma progression were analysed with a Cox proportional hazards model.

Results During a mean follow-up of 38 months, 11 fellow eyes (18.0%) with normal VF at baseline were determined to have VF progression, while 21.3% of affected eyes had VF progression. After adjustment for potential confounding factors, decreased baseline DCP in the fellow eyes was significantly associated with future VF progression (HR 1.33, 95% CI 1.03 to 1.73, p=0.031).

Conclusion Decreased DCP was associated with a higher risk of developing VF damage in NTG patients with unilateral VF loss. Assessments of DCP may help improve the evaluation of the risk of functional deterioration in fellow eyes with an initially normal VF.