Eggs are harder to screen for quality than sperm - mainly because sperm swim around and that can give you an idea of how they are :) Plus each egg produced is a potential child (well, half of), whereas out of one lot of sperm, it doesn't matter if a lot of them are dodgy, as long as there's a few good ones.

The only real way to test for age-related problems is to do a genetic test after fertilisation, which is very expensive and can stop it developing further.