Abstract
Purpose: :
It is unclear whether the thickness of atrophic optic nerves correlates to visual function. Here we evaluate the orbital portion of the optic nerve in patients with optic atrophy using MRI, and compare these measurements with objective tests of vision.
Methods: :
Retrospective review of thirty-nine patients diagnosed with optic atrophy (21 unilateral, 18 bilateral) with orbital MRIs performed at a single institution. Patients were excluded if they had intracranial masses compressing the optic nerve or chiasm, had incomplete or inadequate imaging or documentation of the findings, or had other etiologies of visual loss apart from optic neuropathy. The diameter of the optic nerve and its surrounding sheath at proximal, midpoint, and distal sections were measured by a neuro-radiologist blinded to the patients’ diagnoses. The cross-sectional areas of the optic nerve were calculated, as well as the optic nerve areas as a percent of the adjacent sheath areas. Spearmann rank correlation coefficients were calculated to determine whether these measurements were correlated to visual acuity, color vision, and mean deviation on standard automated perimetry testing.
Results: :
Compared to normal optic nerves, atrophic optic nerves were found to have statistically smaller cross-sectional areas in the anterior section. There was no statistically significant correlation between atrophic optic nerve cross-sectional areas and visual acuity or color vision. However, there was a statistically significant correlation between the atrophic optic nerve areas and mean deviation on automated perimetry in the midpoint section of the nerve.
Conclusions: :
While MRI measurements of atrophic optic nerve thickness do not correlate with visual acuity or color vision, they do show a correlation with visual field.
Keywords: optic nerve • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)