Fetal ocular distance in normal pregnancies.

OBJECTIVE To construct reference ranges of fetal ocular distance (interocular and binocular distance) and to evaluate the relationships between the gestational ages and fetal ocular distance. MATERIAL AND METHOD Six hundred and two normal pregnant women were evaluated from the 15th to 40th week of gestation. Fetal ocular distance (interocular and binocular distances) was added to routine biometric measurements for normal fetuses. The fetal ocular distance (interocular and binocular distances) was also related to gestational age. RESULTS Five hundred and ninety five measurements were used for analyses. A linear regression and correlation were observed between gestational age (GA) and interocular distance (y = 2.304 + 0.510 x GA, R2 = 0.887; p < 0.0001), and binocular distance (y = 2.590 + 1.420 x GA, R2 = 0.953; p < 0.0001). A linear growth function was observed between biparietal diameter (BPD) and both interocular distance (y = 2.854 + 0.203 x BPD, R2 = 0.888; p < 0.0001), and binocular distance (y = 3.893 + 0.568 x BPD, R2 = 0.965; p < 0.0001). CONCLUSION The present study provides normative data of fetal interocular distance and binocular distance. These data may be helpful in detection of fetal hypotelorism or hypertelorism.