Ocular growth in the fetus. 2. Comparative study of the growth of the globe and the orbit and the parameters of fetal growth.

In a previous study, we showed that the growth of the eye during fetal development compared with the other parameters of the fetus was above all connected to the head circumference, which appeared to be the most discriminant measurement. In a second study, we measured the growth of the orbit of the fetus in order to compare it with the growth of the globe and the cranial circumference. Another 60 eyeballs of 30 fetuses of 18-41 weeks gestational age were examined. The corneal diameter (CD) of the cornea was a measurement added to those used in the method in the previous study, and orbital radiography was carried out: the parameters used were the same as in the previous study measured in relation to the CD, orbital diameter (OD) and the biparietal diameter (BPD). The aim of this study was to show the links between the variations in the measurements and to estimate them in relation to fetal growth. The results confirm those of the previous study, and this study also shows that, in estimating the head circumference, the OD and CD are the most accurate indicators. This study was also concerned with the BPD: the best correlation is obtained with the OD, which can be estimated accordingly from the BPD. Although the OD is not in an area studied by ultrasonography (highly dependent on the sectional plane), this study shows that it should perhaps be reconsidered in the prenatal diagnosis of orbital malformation. It would then be necessary to take into account not only the BPD but also the relationship between the OD and the BPD.