Fetal ocular measurements by MRI.

OBJECTIVE

To present fetal magnetic resonance imaging (MRI) ocular measurement ranges by gestational age (GA) in normal and growth-restricted fetuses.

METHODS

A total of 298 pregnant women from the 18th to the 39th week of gestation were imaged using MRI. Ocular measurements including binocular distance (BOD), interocular distance (IOD), transverse ocular diameter (OD) and anterior-posterior (AP) OD were measured. The curve estimation analyses for linear, logarithmic and quadratic models were performed. The ocular measurements of the fetuses with intrauterine growth restriction (IUGR) were compared with that of the normal fetuses.

RESULTS

The fetal eye resembles an ellipsoid with significantly longer OD and shorter AP (t = - 22.07, p < 0.001). The quadratic model was the best model in predicting growth of the fetal BOD, IOD, OD and AP. The ocular measurements of the fetuses with IUGR were significantly different from that of the normal fetuses (BOD: t = 3.58, p < 0.001; IOD: t = 5.73, p < 0.001; OD: t = 3.52, p < 0.001; AP: t = 2.19, p < 0.05).

CONCLUSION

Fetal ocular growth can be readily assessed by fetal MRI. Using the normative data provided in this study, fetal ocular anomalies may be detected. Ocular size is frequently reduced in the condition of IUGR, with potential pathologic impact on postnatal vision.