Ultrasonographic measurement of the optic nerve sheath diameter in dysthyroid optic neuropathy.

Abstract

The aim of this study is to evaluate the optic nerve sheath diameter (ONSD) in eyes with dysthyroid optic neuropathy (DON) and its relationship with clinical characteristics and disease severity. Patients diagnosed as thyroid-associated ophthalmopathy (TAO), with or without DON, and healthy participants were recruited. Vertical and horizontal sectional images of the optic nerve were collected by B-scan ultrasonography. ONSDs at 3 mm and 6 mm behind the eyeball were measured independently by two researchers. Multivariate regression analysis was performed to evaluate the association of ONSD with demographic and ocular parameters in TAO patients. Areas under the receiver operating characteristic curves (AUROCs) were applied to evaluate the diagnostic accuracy of ONSD for DON. A total of 47 healthy eyes, 36 TAO eyes without DON, and 33 eyes with DON were studied. ONSDs at 3 mm and 6 mm of DON eyes were significantly higher than those in non-DON and healthy eyes (all P < 0.05). There was no significant difference in ONSDs between clinically active and inactive eyes (both P > 0.05). DON occurrence showed a positive association with both ONSDs at 3 mm (β = 0.49, 95% CI: 0.14-0.83, P = 0.007) and 6 mm (β = 0.58, 95% CI: 0.20-0.96, P = 0.003). ONSDs at 3 mm and 6 mm showed a desirable diagnostic capacity to distinguish DON from non-DON eyes (AUROC was 0.77 and 0.75, respectively). An increase in ONSD is evident in DON eyes independent of clinical activity. Ultrasound-based ONSD has sufficient ability to distinguish DON from non-DON eyes.