To quantitatively analyze diffusion parameters of the intraorbital optic nerve in healthy adults using magnetic resonance diffusion tensor imaging (MR-DTI), in order to provide baseline data for clinical research on optic neuropathy.

Fifty-five healthy adult volunteers who underwent orbital magnetic resonance imaging (MRI) without contrast at the Eye Hospital of the China Academy of Chinese Medical Sciences between May 2024 and September 2025 were enrolled, including 26 males and 29 females. The subjects ranged in age from 23 to 73 years, with an average age of (46.0±14.0) years. All participants underwent DTI and axial T1-weighted MRI (T1WI) scans using the United Imaging uMR660 1.5T MRI system. Independent sample t-tests were performed on the fractional anisotropy (FA), mean diffusivity (ADC), relative anisotropy (RA), volume ratio (VR), and axial T1WI optic nerve diameter of the dominant (using the cave method) and non-dominant eyes in the young group (age ≤45, 28 subjects) and the middle-aged and elderly group (age ＞45, 27 subjects).

Significant differences were observed in FA, RA, ADC, and VR values between the young and middle-aged/elderly groups (P＜0.01). FA and RA values correlated negatively with age (ρ=-0.420, P＜0.001), while ADC and VR values correlated positively with age (ρ=0.450, P＜0.001). No significant associations were found with gender or eye dominance.

DTI enables the quantitative assessment of optic nerve diffusion parameters, establishing normative baseline data for research into adult optic neuropathies. This capability supports early disease diagnosis and highlights the importance of using age-matched control groups in future DTI studies of optic nerve disorders. Notably, ocular dominance factors were not considered in this analysis—a point of particular relevance in conditions that may present unilaterally..