Many causes of epiphora are unrelated to anatomical problems in the nasolacrimal drainage apparatus. Problems in the upper lacrimal system have often been under-recognized as a cause of epiphora.

One can see that the problems associated with the upper lacrimal drainage system can be complex. We can begin to consider these problems by first establishing whether true epiphora exists.

Although epiphora can be due to either excessive tear production or abnormal drainage through the nasolacrimal system, in rabbits the most common cause of epiphora is a blocked nasolacrimal duct.