Visual function changes of dysthyroid optic neuropathy and ROC curve analysis for early diagnostic indicators

Dysthyroid optic neuropathy (DON) is a class of diseases that makes seriously endanger to the vision of patients with thyroid-associated ophthalmopathy. This study aims to observe the visual function changes in patients with DON, and to evaluate the diagnostic value of indicators diagnosing DON.

A retrospective study was conducted on 98 eyes of 49 patients with dysthyroid optic neuropathy (DON) who were treated in Xiangya Hospital of Central South University from January 2017 to December 2019. All patients were received the examination of best corrected visual acuity (BCVA), Humphrey visual field, visual evoked potential (VEP), and contrast sensitivity. Ninety-eight eyes were divided into a DON group (45 eyes) and a non-DON group (53 eyes). T-test was used to compare the related indicators between the 2 groups. The sensitivity and specificity of each indicator were analyzed by receiver operating characteristic (ROC) curve.

The BCVA and visual field index (VFI) of the DON group were significantly lower than those of the non-DON group (all P<0.05). The mean deviation (MD) and pattern standard deviation (PSD) of the DON group were significantly higher than those of the non-DON group (all P<0.05). The low frequency contrast sensitivity (CSL), medium frequency contrast sensitivity (CSM), and high frequency contrast sensitivity (CSH) of the DON group were significantly lower than those of the non-DON group (all P<0.05), with CSH being particularly prominent. Compared with the non-DON group, at spatial frequencies of 15°, 30°, and 60°, the amplitude of N135 wave was significantly reduced, and the latency of N75 wave, P100 wave, and N135 wave was significantly prolonged in the DON group (all P<0.05); at spatial frequencies of 15° and 30°, the amplitude of P100 wave was significantly reduced in the DON group (P<0.05). The ROC curve analysis results showed that the area under the curve (AUC) of VFI, CSL, CSM, CSH and 15° P100 amplitude diagnosing DON were 0.812, 0.841, 0.880, 0.784, and 0.791, respectively, with CSM possessing the highest sensitivity and specificity.

The visual function of patients with DON is decreased. VFI, contrast sensitivity of low, medium, and high frequency, and 15° P100 wave amplitude might be effective indicators for early diagnosis of DON.