Optic nerve elasticity and sheath diameter in amblyopia: A cross-sectional study

This study aimed to examine and compare optic nerve elasticity (ONE) and optic nerve sheath diameter (ONSD) in amblyopic eyes and healthy fellow eyes. This prospective, observational study was conducted between October 2019 and December 2019. A total of 21 patients diagnosed with unilateral amblyopia were included in the study. The ONSD of both eyes of each patient was measured by ultrasonography, and ONE was measured by shear-wave elastography. The results were compared between healthy eyes and amblyopic eyes. Eleven female and 10 male patients were included in the study, and the median age of the patients was 25 (interquartile range [IQR]: 20-31) years. The mean ONSD of amblyopic eyes (2.37 ± 0.36) was significantly lower than that of healthy eyes (2.54 ± 0.39) (P = .014). Although the median ONE value of the amblyopic eyes (2.73 [IQR = 1.52-3.84]) was higher than that of healthy eyes (2.63 [IQR = 1.70-4.65]), this difference was not significant (P = .931). Mean ONSD values were significantly lower in amblyopic eyes compared with healthy fellow eyes, whereas no significant difference was observed in ONE values between the 2 groups. These findings suggest that reduced ONSD may represent a structural alteration associated with amblyopia. However, because of the cross-sectional design and limited sample size, the biological and clinical significance of these findings remains uncertain and requires further investigation in larger prospective studies.