An enucleation is the surgical removal of a horse's eye. There are many indications for which this surgery would be performed, including trauma, neoplasia (cancer), extensive infection, or any condition causing pain in a blind eye. In Misty's case, the procedure was recommended due to an acute worsening of uveitis and ulceration along with equine recurrent uveitis flare-ups that had been occurring over the last four years.
This surgery can be performed under continuous sedation with the horse standing, or under general anesthesia. In a relatively calm horse that will stand under sedation, it is a very reasonable procedure to do standing. This allows us to avoid the risks of general anesthesia. Regional nerve blocks are performed prior to the procedure so that the horse cannot feel the eye or the area surrounding it.
Once the surgical site is draped and scrubbed, the eyelids themselves are sutured closed, and an incision is made parallel to each eyelid. The eye is dissected out from the soft tissues and muscles that surround it, and it is removed.
The incision is sutured closed in several layers.
A pressure bandage is often then placed over the incision overnight to decrease the amount of swelling.
We typically initially see swelling under the incision that will gradually subside, leaving a somewhat concave appearance.
The sutures remain in place for 14 days, and then are removed. At the time of suture removal, Misty came cantering across the pasture with her pasturemate when she was called up. The incision appeared to be healing very well, and she did not seem adversely affected by the loss of the eye.
In fact, the majority of horses do extremely well after an enuclation surgery. Many were so painful with the disease process in the eye that necessitated the surgery that they are considerably less painful immediately after surgery, despite the surgery itself. It is often a difficult decision for owners to make, but for the horse this surgery can make a bit difference in health and comfort. Quality of life in these horses often improves dramatically following surgery. One retrospective research study out of the University of Pennsylvania in 2010 looked at the records of 34 horses that had one eye removed for various reasons. In this study, 85% of the horses returned to work in their previous discipline, including racing, hunter/jumper, dressage, pleasure riding, trail riding, steeplechase, and eventing. Although it is ultimately necessary for each individual owner, trainer, or rider to make an informed decision about the safety of riding any horse with impaired vision, it is definitely true that the majority of these horses are able to return to performance.