Equine Case Study: Epithelial Iris Cyst

Equine Case Study: Epithelial Iris Cyst

This case was a 9 year old Arab gelding who was presented to the vet because the owner noticed a problem with his vision in the right eye. The gelding had all of a sudden become spooky on the right side when being ridden and also had become very reluctant for people to approach him on the right side.

On examination of Kaisers right eye it was immediately apparent that there was a spherical structure in his lower iris, which was not normal.

Eye

There were a few options as to what this abnormal structure may have been and either an epithelial iris cyst or a melanoma were the two most likely possibilities. In order to get a definitive diagnosis we went on to carry out an ultrasonographic evaluation of Kaiser’s right eye and this revealed a spherical structure which had a white outline and was totally black in the middle. These ultrasonographic findings confirmed that it was an iris cyst we were dealing with and not a melanoma as melanomas tend to be more irregular in outline and have a solid white appearance on ultrasound rather than the cyst which is black in the middle due to the fact it is fluid filled.

Eye

Eye

If the iris cyst is not affecting the horses vision then we opt to leave them well alone. However, in Kaiser’s case it was clear that the cyst was affecting his vision and therefore it was evident that we needed to treat the cyst. Consequently, Kaiser underwent laser ablation (removal) of the cyst under standing sedation.

Two weeks following surgery Kaiser’s vision had returned to normal and there was no evidence of any residual cyst tissue in the eye. It is now six months since the surgery and he is continuing to do well.