GROWTH OF THE FETAL ORBIT AND LENS IN NORMAL PREGNANCIES

Objective To construct nomograms of the size of the fetal orbit and le ns during gestation. Subjects The study group included 349 normal preg nant women at 14-36 weeks' gestation. Methods Routine biometric measur ements were obtained In all the participants; these included biparieta l diameter, head and abdominal circumferences, measurements of the lon g bones and the diameters of the fetal orbit and lens. The orbital and lens circumference measurements were also related to gestational ages . Results A linear growth function was observed between gestational ag e (GA) and orbital diameter (r=0.94; p < 0.00001; y = -0.66 + 0.5 x GA ), orbital circumference (r = 0.94; p < 0.00001; p = -2.1 + 1.5 x GA) and orbital area (r = 0.94; p < 0.00001; y = -98.1 + 8.3 x GA). Signif icant correlation was also found between femoral length (FL) and orbit al diameter (r=0.95; p < 0.00001; y = 3.3 + 1.9 x FL), orbital circumf erence (r = 0.95; p < 0.00001; y = 10.3 + 5.9 x FL) and orbital area ( r = 0.93; p < 0.00001; y = -28.2 + 32.2 x FL). A linear growth functio n was observed between orbital circumference and biparietal diameter ( r=0.94; p < 0.00001) and head circumference (r = 0.95; p < 0.00001). A linear growth function was also observed between gestational age and the diameter of the lens (r = 0.89; p < 0.00001; y = 0.88 + 1.4 x GA) the circumference of the lens (r = 0.89; p < 0.00001; y = 2.78 + 0.4 x GA) and the area of the lens (r = 0.89; p < 0.00001; y = -7.95 + 1.0 x GA). The correlation was found between the ratios of the diameters, circumferences and areas of the lens and the orbit. Conclusions These results provide normative data of the growth of the fetal orbit and le ns and may aid future studies relating to fetal eye anomalies.