Trabeculotomy ab externo and goniotomy seem to be in many ways equivalent, and both are particularly successful in previously unoperated cases of primary infantile glaucoma that become apparent postnatally but before the age of 1 year. It may be more difficult to achieve a technically perfect procedure with trabeculotomy than it is with goniotomy, but trabeculotomy has an advantage in cases where the cornea is so cloudy that the angle cannot be seen well enough for goniotomy under direct visualization. Overall, the two procedures seem equally effective and safe.