LONG-TERM-RESULTS OF PARS-PLANA-VITRECTOMY IN EQUINE RECURRENT UVEITIS

Equine recurrent uveitis (ERU) is an inflammation of all parts of the uvea. The etiology and pathogenesis are not fully known. Even with opt imal medical treatment the prognosis, in many cases, is not very good due to the recurring nature of the disease and the progressive destruc tion of the intra-ocular structures. In 1989 Werry and Gerhards introd uced the surgical treatment of ERU during the inflammation free interv al. in this paper, the treatment of horses with chronic recurrent uvei tis by pars-plana-vitrectomy is documented. From previously operated p atients, 43 eyes from 38 horses were examined in their home-stalls, wi th a six to sixty-Seven month interval since the operation. The examin ation consisted of a complete ophthalmological examination followed by measuring of the intra-ocular pressure. According to the horse-owners , 42 of the 43 eyes had no uveitic attack since the surgery. More than 70 % of the eyes retained their ability to see, with 39,5 % reporting improved vision and 32,6 % hindered vision. The most common cause for reduced vision or even blindness was a cataract in 19 eyes. The treat ment through a combination of vitrectomy and phacectomy, as used in hu man medicine, is not yet possible in horses. A majority of the eyes (3 1 of 43) had a normal intra-ocular pressure. 32 of 43 pars-plana-vitre ctomies had no problems whatsoever. The most frequent complication dur ing the surgery, experienced in 4 eyes, was intra-ocular haemorrhage. Long-term complications were the development of atrophia bulbi (7 eyes ), ablatio retinae (4 eyes), phthisis bulbi (2 eyes) and cataract deve lopment (19 eyes). Since chronic ocular inflammation could be the caus e of these complications, it is not possible to ascribe them purely to the vitrectomy. The results of these examinations show that pars-plan a-vitrectomy is a significant improvement in the treatment of equine r ecurrent uveitis. This treatment may improve vision and stop the progr ession of the uveitic destruction of the eye. In no case medical treat ment should be left out of the treatment of an acute uveitic attack an d also as pre-surgical measurement. it is concluded, that horses suffe ring from ERU should be operated on as soon as possible after the seco nd or third attack. The suspected reason for the therapeutic effect of the pars-plana-vitrectomy is the reduction of local immunological pro cesses through the removal of the inflammatority-changed vitreous (imm unological memory of the uveitis'').