Expert: Jessica - 9/13/2009

Question
Hey Jessica! I have just adopted a ten-week-old kitten that a friend of mine rescued last week. He is a Siamese (my first!) and I had him to the vet earlier this week, and they gave him a good bill of health save for the usual de-worming and booster shots.

He has bright blue eyes which are a bit crossed, and I attributed that to his breed. This morning, though, one of his pupils isn't dialting and the iris is turning a bit yellow. Of course, it is Sunday and all the vets in my area are closed.

Any advice would be much appreciated! I'm quite worried about him!

Answer
Hi Jessa.  You have good cause to be worried.  This sounds like a condition called uveitis.  This is an inflammation of the inner globe of the eye, and anterior uveitis in specific affects the iris and causes the discoloration you’re seeing.  It also causes a condition called anisocoria – uneven pupil size.

Anterior uveitis can be caused by all sorts of things.  It may be caused by a trauma such as a deep penetrating poke in the eye (if you have any other cats, a claw in the eye could cause this).  It may be cause by autoimmune disease.  Often, it’s caused by infection, which can be localized in the eye, or a body-wide infection such as toxoplasmosis, feline infectious peritonitis or feline leukemia.  Toxoplasmosis is treatable, but the other two are not.  You also have the possibility that it may be caused by cancer.  And in a great many cases, no cause is ever found.

The vet will usually put a special drop in the kitty’s eye.  This is a stain that will fluoresce  if there are any tears or ulcers on the cat’s cornea.  If the cornea is damaged, the treatment for uveitis is generally a good antibiotic eye ointment or drop.  If the cornea is not damaged, a steroidal agent will also usually be given.  This is because uveitis tends to cause swelling in the eyeball, and quite a bit of discomfort.  The steroid can help shrink down some of the swelling and relieve pain.  If a steroid is not used, there is the potential for the condition to escalate to glaucoma.  However, if a steroid is used when the cornea is damaged, the eye may actually rupture, so a steroid must not be used until the cornea is healed.

In most cases of uveitis, there is some vision loss.  The sooner the kitty is treated, the greater his chances are at preserving his vision.  Some cats regain vision once the condition is treated if it is caught early, but some cats form scar tissue in their line of vision that will at least partially obscure their sight.  In some cases, the pressure in the eye builds up so much that the lens become pushed out of place, or the retina becomes detached.  This causes permanent and total vision loss in that eye unless you opt to have a veterinary ophthalmologist try to repair it surgically.  However, cats compensate for the loss well, and this has never affected any of my cats negatively.

I think your kitty will be fine until tomorrow, but get him in to be properly diagnosed and treated when the vet opens!  Good luck!

Jessica