according to studies there is no scientific proof to tell that exposure to solar eclipse can cause birth defects like cleft lip etc,
an early scan at 8 weeks may not detect these anomalies,
by this scan you can detect the gestational age
of the fetus and can monitor the proper growth,
to detect anomalies ultrasound
around 18 to 20 weeks is better time which is called anomaly scan.
so with your doctor's advice you can follow the growth of the baby with regular antenatal check ups and ultrasound.