Surgical therapy for ocular setariasis in horses

Nine cases of ocular setariasis in horses were reported with epiphora, mucoid discharge along with cloudiness of cornea of the affected eye. General ophthalmic examination revealed rapid movement of thread like worm in the anterior chamber of the eye. After sedation with diazepam 0.5 mg/kg i.v, regional nerve blocks viz. supraorbital, auriculopalpebral and retrobulbar nerve blocks of the affected eyes were carried out in addition to the topical instillation of 4% lignocaine. Paracentesis oculi technique using 4 mm stab incision with BP blade No. 11 at 12 O'clock position, 4 mm away from the limbus, was made in all the eyes. The worm was grasped and withdrawn using alligator forceps while the cornea was held with corneal forceps. The worm could not be removed in 2 cases due to hyphema and trapping of the worm in between cornea and iris. Parasitological examination revealed that all the worms were Setaria digitata. Post-operatively, tetanus toxoid 5 mL i.m, tobramycin and flurbiprofen eye drops topically for 5 days along with levamisole 7.5 mg/kg orally was recommended in all the cases. In 75% of eyes (n=6), the corneal transparency was regained by 8^th day postoperatively and in remaining eyes it took 14 days for the same. The 12 O'clock position at the limbus was a safe site for stab incision for removal of ocular worm with least complications.