Entropion is an abnormality in which the eyelids curl inwards. The result is that the hairs on the outside of the eyelids now irritate the eyeball. In severe cases, this can lead to perforation of the eyeball and permanent blindness. In theory, the condition can occur in any animal species but is more common with dogs and cats.

Usually, the cause is a “construction defect”; some eyelids are not entirely reasonable formed. This form is congenital and often gives complaints at a young age. This is, in many cases, a hereditary problem. Inbreeding, this has to be taken into account. Another form arises after prolonged, untreated inflammation of the eye. By constantly squeezing the eye, entropion can also develop. This form does not always disappear when the swelling has healed.