Equine amniotic membrane transplantation for corneal ulceration and keratomalacia in three horses

Amniotic membrane has antifibrotic, anti-angiogenic and antiprotease properties. This retrospective study was designed to investigate the use of equine amniotic membrane transplants (AMT) at preserving vision, maintaining the structural integrity of the globe and maximizing cosmesis in equine eyes with corneal ulceration and severe keratomalacia.

Equine amnion had previously been aseptically harvested from a 12-year-old Thoroughbred mare during an elective Cesarean section. Sections of amnion were stored at -80 degrees C and thawed as needed. Records of equine cases at the University of Florida with keratomalacia that received an AMT without adjunctive conjunctival grafting were examined. Clinical description, details of medical and surgical treatment, globe survival and visual outcome were documented. Etiologies were determined by cytology, culture or histology.

Three horses with corneal ulceration and severe keratomalacia received an AMT without conjunctival graft between December 2002 and April 2003. Pseudomonas spp. were cultured from all three eyes, with evidence of a concurrent fungal infection in two eyes. The three ulcers were 50, 72, and 76% of corneal diameter, and each one worsened in the face of aggressive medical therapy. In all three cases, the AMT sloughed over a 4 to 6-week period. At last follow-up, all three eyes receiving AMT were comfortable and receiving no medication, with light perception and an inconsistent location-dependent menace response. All three horses returned to their prior work.

Results of a small number of equine AMT suggest that amnion can be used successfully to preserve both globe structure and limited vision, as well as optimize cosmesis, in horse eyes with corneal ulceration and severe keratomalacia.