This is a complicated issue, often ignored or misunderstood. This article is not complete, but gives some information which I will perhaps remember to add to later.
HEALTHY EYES
An excellent eye, firm but not tight rim, no sign of entropion or extropion, minimal sign of haw, lid still slightly slack so tears can rapidly and easily flush out any seed collected if working in a field, eye not so open as to collect seed in a scoop like fashion and the same applies to other debris such as dust.
Technically correct until 1-1-2009, this eye is more open and shows a significant amount of haw.
UNHEALTHY EYES – ENTROPIAN
viewed from the front, the lower lid shows entropion (rolling in of the lid, in clinical cases, the eye leashes brush on and damage the actual eye ball)
same dog (from the 1980s) viewed from the side
Entropion, as a life long disease, is evident by 6 weeks of age. If there is no sign until 9 weeks of age, then there is a change it will resolve itself as the baby’s head develops and the eye shape settles (after the major part of head growth is achieved and the last big molars cut). It should not be causing eye inflammation nor constant tear staining at anytime, if these occur it is likely to be a life long issue and a good breeder will not use the dog in their breeding programme.