THE DESCRIPTIVE EPIDEMIOLOGY OF ANOPHTHALMIA AND MICROPHTHALMIA

Background. Anophthalmia and microphthalmia are serious eye malformati ons which recently have been associated with exposure to Benomyl. Data on these malformations are scarce in the literature and reported prev alences at birth vary strongly. Methods. Data from three large registe rs of congenital malformations were analysed and comprised 849 malform ed infants based on close to 5.7 million births.Results. This is the l argest available epidemiological study on anophthalmia and microphthal mia. The prevalence at birth was 1.50 per 10 000, varying between 0.92 and 2.29 between registers but not varying significantly between race s in the California register. The variation in rates was mainly due to different inclusion of chromosomally abnormal infants (mainly trisomy 13) and of infants with microphthalmia occurring with major non-eye m alformations. On the other hand, rates of anophthalmia and isolated mi crophthalmia were similar. Other major non-eye malformations were foun d in 73% of infants without a known chromosome anomaly. The malformati on was bilateral in 53-60% of infants except when microphthalmia exist ed without any other malformations when only 27% were bilateral. Sex d istribution was normal, there was a slight excess of twins, and an inc reased risk at high maternal age. Conclusions. In analytical studies s earching for the cause of these malformations, it may be useful to res trict the analysis to infants with anophthalmia or isolated microphtha lmia as the recording of such cases seems to be more reliable than of microphthalmia occurring with other malformations. The conclusions pre sented in the literature on the possible effect of Benomyl are partly based on data with apparent very incomplete ascertainment.