DNMT3A and Anophthalmia: True anophthalmia also occurred in 4 out of 203 (2%) Dnmt3a2−/− mice, and 1 out of 560 (0.18%) Dnmt3a2+/- mice, characterized by the complete absence of one or both ocular structures due to failed optic vesicle formation during early embryogenesis (Fig. 2C and Table 1).