In a large genotype–phenotype correlation of the PAX6 Mutation Database, Tzoulaki et al. [15] established that mutations introducing a premature termination codon (PTC) were predominantly associated with aniridia, whereas non-aniridia phenotypes, such as isolated foveal hypoplasia, microphthalmia, and optic nerve defects, were predominantly caused by missense mutations. This evidence concerns the gene PAX6 and microphthalmia.