equine cataract surgery
Cataracts are opacities of the lens and disrupt the passage of light through the eye onto the retina. There are many types of cataract, some worse than others and unfortunately once a cataract has formed there is no medication currently available that can reverse the changes. If the cataract is impairing vision and the eye is otherwise healthy, surgical removal can be considered.
With improvements in surgical instrumentation and facilities, cataract surgery in the horse has enjoyed an improved success rate over recent years. However, cataract surgery in the horse is more prone to complications than in people since the equine lens is larger than our own and the equine eye will react more intensely to surgical intervention.
The surgical technique used to remove the cataract is the same that is used in people. A small (3.2mm) incision is made at the edge of the cornea, and through that a window is cut in the front of the lens. An ultrasonic probe is then inserted into the lens and vibrates at high frequency to break up the lens (phacoemulsification) and aspirate the fragments. This leaves an empty capsular bag which used to contain the cataractous lens, and into which an artificial intra-ocular lens can now be inserted.
With the development of aspheric multifaceted lenses we now have dedicated equine intra-ocular lenses, large enough and with sufficient optical power for the equine eye, that can be folded and introduced through a small corneal incision.
As always cataract surgery case selection is critical but in cases of cataract formation secondary to a recurrent uveitis, cataract removal may be indicated if there are no signs of any significant retinal lesions.