Disorder - Iris defects

Organ Systems Involved
Nervous/sensory

Alternative disorders described within LIDA

Glaucoma; Uveitis; Iris aplasia; Persistent pupillary membranes; Heterochromia; Iris colobomas

Presenting Signs

Iris defects are abnormalities associated with the coloured part of the eye that controls the light levels inside the eye. Iris defects include:

• Heterochromia - a difference in colour between the left and right iris of an cat or between parts of the same iris due to a lack of pigment in the cells of the iris. One eye may be blue and the other yellow to green.
  
• Waardenburg's syndrome - different coloured iris plus deafness in the cat.
  
• Iris naevus - a condition involving small spots of increased pigmentation which may or may not become cancerous.
  
• Persistent pupillary membranes - remnants of an embryonic vascular network that arise from the iris surface do not fully regress following birth. Large remnants can produce opacities in the iris of a cat and may impair vision.
  
• iridial colobomas - characterised by an area of the iris that is very thin or has a hole as has never formed properly. The effect on vision can be mild or severe.
  
• Chediak-Higashi syndrome - a pale iris and retina discolouration. The irises are usually a pale yellow green as opposed to the normal bold copper or yellow.

Cats at Risk

Heterochromia is most common in white cats. Waardenburg's syndrome occurs in blue eyed white cats.

Breeds Affected
Abyssinian
Burmese
Persian


Treatment

Iris naevus can be treated with surgery. The other conditions have no treatment.

PubMed References
Iris defects

Contributor
Claudia Quai