Penetrating keratoplasty for treatment of corneal abscesses in horses – case report

This case report describes the surgical technique and outcome of allograft transplantation to treat full thickness corneal abscesses in three horses. In all three cases penetrating keratoplasty was performed. Each affected eye had an abscess within the corneal stroma. An initial full thickness circular corneal incision was made around the lesion. After excision of the stromal abscess the created defect was replaced with a larger diameter full thickness donor graft and the initial corneal incision was repaired. All of the horses that underwent penetrating keratoplasty procedure healed with a scar at the graft site and remained visual. Penetrating keratoplasty is an effective technique for surgical removal of medically nonresponsive full thickness stromal abscess in horses and results in a visual and cosmetically acceptable globe. The advantages of this technique compared to medical therapy are that there is less scarring, shorter healing times and less damage of the globe because of the concurrent uveitis. To the authors’ knowledge, clinical experience with penetrating keratoplasty in horses has not been reported in Europe so far. Equine, corneal transplant, stromal abscess, uveitis Full thickness corneal abscess is a real challenge for the treating veterinarian and needs surgical repair. Penetrating keratoplasty (PK) has been described in the horse for full thickness stromal abscess (SA) (Andrew 2000; Plummer 2008; Brooks 2008, 2010). Corneal transplantation for treatment of severe inflammatory keratopathies has been performed successfully in horses at the University of Florida since 1993 (Brooks 2008). Corneal SA in the horse is a major disease that has the potential to render a previously normal eye extremely painful and blind (Plummer 2008). A SA may develop during the healing of a minor corneal defect if the surrounding epithelial cells migrate and divide over the defect, thus sealing microorganisms within the stroma (Hendrix 1995). The disease consists of two major components: the corneal lesion itself, which is an accumulation of inflammatory cells and debris with or without an infectious agent or foreign body, and the secondary uveitis that follows the corneal insult (Andrew 2010). Causative agents cannot be isolated in all cases, however, the majority of the cases are caused by fungus, gram-positive cocci, or gram-negative rods. Clinically it is a yellow-white stromal infiltrate of variable size and depth with corneal oedema, neovascularization and iridocyclitis (Hamil ton 1994). If medical therapy alone is insufficient or the SA is situated deep within the stroma or results in severe iridocyclitis, a surgical approach is indicated. Surgical management has been associated with a more rapid recovery time and better visual outcome (Hendrix 1995). There is a lack of case reports from European clinics. Although fungal keratitis and SA are not rare in European horses, PK surgeries have not been described in complicated clinical cases so far in Europe. The aim of this article was to describe the adequate technique and common complications of penetrating keratoplasty. ACTA VET. BRNO 2013, 82: 303–307; doi:10.2754/avb201382030303 Address for correspondence: Zita Makra Department of Large Animal Clinical Sciences Veterinary Faculty, Szent István University Üllő, Dóra major, 2225, Hungary Phone: +36-30-605-3472 E-mail: [email protected] http://actavet.vfu.cz/ Materials and Methods Three clinical cases of equine corneal abscesses were referred to the Large Animal Clinic of the Veterinary Faculty, Szent Istvan University, Hungary in the years 2010–2012. Horse profiles are described in Table 1. The first case was a dressage sport pony, the second and third cases were hobby horses. All three horses were presented for evaluation of profound ocular pain with corneal opacity that had been present prior to referral for 14–28 days, and treated with different antimicrobials and antiinflammatory drugs by the referring veterinarian, although without improvement.