Intravitreal injection of low-dose gentamicin for the treatment of ERU-affected horses

Abstract

Aim of the study was the retrospective evaluation regarding vision and recurrence in equine recurrent uveitis (ERU)-affected horses treated by intravitreal low-dose gentamicin injection in Tierklinik Alt Sammit during the years 2006-2013. The study included 50 equine patients (61 ERU-affected eyes) of different age and breed with different stages of ERU. The solution for the injection contained 4.0 mg sterile gentamicin per eye. The injection was performed according to the procedure described by Pinard et al. in 2005 under general anaesthesia in lateral recumbency of the patient and within a non-inflammatory period. The patients were monitored over a postoperative period of 2-96 months (mean 25.8 months, median 15 months). A total of 56 out of 61 treated eyes displayed no recurrence of ERU during the follow-up period. Recurrence of a single uveitic attack occurred in five eyes (8.2 %) within a period of 2 weeks to 28 months after surgery. Long-term stable vision was achieved in 43 out of 61 eyes (70.5 %). Postoperative blindness developed in 18 eyes, the majority hereof had already preoperatively displayed obvious pathologic ophthalmic findings with partly highly impaired vision. The main reason for a vision loss was the progression of a preoperatively existing cataract formation. Perioperative complications were limited to vitreous reflux into the subconjunctival space (two cases), subconjunctival haemorrhage in the area of the injection site (two cases), vitreous haemorrhage (one case) and two cases of immediate postoperative pain reaction associated with the intravitreal injection. The results of the therapy regarding the reduction of the recurrence rate and preservation of vision are comparable to those of vitrectomy. The complication rate is extremely low when using both the correct injection technique and amount of gentamicin solution. Therefore, the intravitreal injection of low-dose gentamicin is an inexpensive and uncomplicated alternative to vitrectomy.