Evaluation of Visual Field Index in Toxic, Nutritional, and Hereditary Optic Neuropathies

Leber hereditary optic neuropathy (LHON), toxic optic neuropathy, and nutritional optic neuropathy are three conditions that preferentially affect the metabolically active cells of the papillomacular bundle, causing bilateral optic neuropathy with central vision loss. Herein, we sought to evaluate the visual field index (VFI) as a useful tool for quantifying visual field loss in these optic neuropathies, through comparison with the mean deviation (MD). This was a single center, retrospective, cross-sectional study. Patients were identified using ICD-10 codes, and charts were manually reviewed to confirm the diagnosis. The toxic and nutritional groups were combined into a single cohort due to low numbers and similar presentations, toxic-nutritional optic neuropathy (TNON). Inclusion criteria required automated visual fields. The primary outcome was the correlation between VFI and MD. Fifty-three patients met inclusion criteria: 30 LHON and 23 TNON. Among patients with LHON, there was a strong correlation (r = 0.988 OD, r = 0.975 OS) between the VFI and MD in both eyes. Each one decibel decrease in MD correlated with a 3% decrease in VFI (p < .001 OD, p < .001 OS). In patients with TNON, there also was a strong correlation (r = 0.980 OD, r = 0.985 OS) between the VFI and MD. A one decibel decrease in MD correlated with a 3% decrease in VFI (95%CI: 2.6, 3.2, p < .001 OD, p < .001 OS). VFI demonstrates a strong correlation to MD in both LHON and TNON groups. These findings support the use of VFI to evaluate and explain vision loss in these patient groups and warrant further research into monitoring progression.