What can we learn from the thalidomide experience

Abstract

The thalidomide tragedy of the early 1960s resulted in a great number of studies and reports involving many specialties of medicine. Because of the estimated large number of affected children (5000+) worldwide exposed to this potent teratogen, and the many informative cases in which the exposure time was known, a teratogenic timetable was constructed relating affected structures to the time of exposure. This demonstrated that thalidomide had a teratogenic effect between approximately 20 to 36 days after fertilization. We found that Duane syndrome and its variants were prominent in individuals who were exposed to thalidomide early in the sensitive period (days 20 to 26±). Other anomalies associated with this early effect were aberrant tearing, facial nerve palsy, ear malformations, and autism. Structural eye malformations were less frequent in this early phase, appearing slightly later in the sensitive period. This study summarizes the ophthalmologic findings from a number of studies and compares them with respect to the implications of time of exposure. Because the timing of anomalies such as external ear and limb malformations are well established in the thalidomide literature, correlation with associated eye anomalies gives insight into the approximate timing of the causative teratogen exposure.