Distichiasis is an eye defect in which one or more abnormal eyelashes grow toward the cornea rather than away from it. Often these lashes are so small and fine they cause no difficulty. Sometimes, however, they are stiff enough that they scratch the cornea every time the dog blinks. This can cause pain and corneal scarring if the lash is not removed. Distichia (the abnormal lashes) can occur at any point in a dog’s lifetime. Minor distichia will pass an eye exam.
Distichiasis is common in Australian Shepherds. The condition is inherited, though the mode of inheritance is not known. If a dog has distichiasis bad enough to require surgical removal of the lashes it should not be bred. If a dog has mild distichiasis that will pass the US eye exams ig can be bred to mates that do not have distichiasis from families not known to have the condition.