Ultrasound imaging of the fetal optic nerve from a different plane

Objective In this study, we aimed to visualize the fetal optic nerve and its sheath in a lateral oblique plane by ultrasound. Methods This cross-sectional prospective study was conducted at 20–22 weeks of gestation on healthy pregnant women who applied to our perinatology clinic for anomaly screening. Optic nerve sheath diameter (ONSD) measurements were taken from the lateral orbital and the retroorbital planes twice by the same sonographer. Ultrasound durations were recorded. Intraobserver variability was calculated for both techniques. The Bland-Altman analysis was performed for the lateral orbital technique. Results A total of 45 pregnant women were evaluated in the study. The intraclass correlation coefficient value of the lateral orbital technique was 0.722 (p<0.001), suggesting that the ONSD was measured similarly by the same observer. The ONSD mean measured by the lateral orbital (LO) technique was higher than the ONSD mean measured by the retroorbital (RO) technique (2.10±0.13 vs 1.21±0.13 mm, p<0.001). The ONSD measurement with the LO technique was determined to be more time-effective than the RO technique (129.6±31.3 vs 228.2±32.7 sec, p<0.001). Conclusion It is demonstrated that by using the lateral orbital technique, the optic nerve and its sheath can be visualized separately without the shadowing artifact of the lens. This technique also takes less time than the RO technique. There is a need for more extensive research on this subject with magnetic resonance imaging (MRI) confirmation.