Visual outcome after corneal transplantation for corneal perforation and iris prolapse in 37 horses: 1998-2010.

REASONS FOR PERFORMING STUDY: We wanted to investigate the visual outcome of horses presented with iris prolapse and treated with corneal transplantation.

OBJECTIVE: To evaluate the visual outcome of horses with iris prolapse treated with penetrating keratoplasty alone and penetrating keratoplasty in combination with overlying conjunctival or amniotic membrane grafting.

METHODS: A retrospective medical records study of horses presented to the University of Florida Veterinary Medical Center for iris prolapse and treated with penetrating keratoplasty in the period of 1998-2010. Data collected from the medical records included signalment, clinical descriptions of ocular lesions, treatments, and therapeutic outcome.

RESULTS: Iris prolapses in this study were caused by corneal ulcers with keratomalacia (n = 37). All horses were treated medically for infection, hyperproteinase activity and iridocyclitis, and then surgically treated with either penetrating keratoplasty alone (n = 9) or penetrating keratoplasty with either a conjunctival pedicle flap (n = 22), amniotic membrane transplant (n = 5) or amnion membrane and conjunctival pedicle flap (n = 1). The eyes were visual postoperatively in a majority of the cases (n = 24; 64.9%). Limited vision was noted in 6 eyes (16.2%), 3 eyes became phthisical (8.1%) and 4 globes were enucleated (10.8%). Graft rejection manifested as some degree of donor corneal graft opacification in all cases. Anterior synechiae were present in 48.6% of the eyes. Wound dehiscence and aqueous humour leakage were also common as post operative problems.

CONCLUSION: Penetrating keratoplasty alone or in combination with an overlying graft of conjunctiva or amniotic membrane can achieve a successful visual outcome in a high percentage of horses with iris prolapse.