LACRIMAL SYSTEM

-        The condition is congenital and is often characterized by epiphora, although some animals are relatively asymptomatic and epiphora may not become apparent until several weeks of age, when tear production increases.

-        In dogs, imperforate puncta (usually of the inferior puncta) and punctal aplasia are common.

Diagnosis

 By examination of the normal location of the puncta with magnification and from the inability to cannulate or probe the puncta with a small polytetrafluoroethylene (Teflon) IV catheter (minus needle),a lacrimal cannula, or fine nylon thread.

Treatment:

              1. Surgical opening of the affected punctum is performed. A lacrimal cannula is inserted into the patent punctum or at the nasal punctum and flushing is performed under pressure.  

Antibiotic-corticosteroid preparations are applied for 7 to 10 days to prevent scarring and obstruction. Daily dilation and flushing may be needed for a few days to prevent closure. If the membrane is thick or bleeds when incised the nasolacrimal system may need to be cannulated for 1 to 3 weeks to prevent fibrosis of the newly created stoma.

Fig.5: Repair of imperforate punctum by pressurized fluid. A, The opposing punctum is cannulated, and pressure is applied via a saline-filled syringe to elevate the obstructing conjunctiva over the other punctum . B, The tissue is grasped with fine forceps and incised with strabismus scissors or other fine scissors (David et al.,2008).

2- The overlying conjunctiva may be removed   through retrograde probing with fine nylon thread (2/0) from the nasal opening. . This procedure ismost useful for the superior punctum, because it is more difficult to pass a probe into the inferior punctum from the nasal end.

Fig.6:  Retrograde probing of imperforate punctum. The nasal meatus of the nasolacrimal duct is probed using a nylon (2/0) thread. The probe is passed up to elevate the obstructing conjunctiva, which is excised (David et al.,2008).