Attack of the Killer Grass Awns

This poor little dog managed to get these 4 little grass awns trapped in the sac under the upper eyelid on the left eye. The foreign bodies then proceeded to wear a little ulceration on the cornea. In the images above, the neon green thing is the ulcer after it has been stained and looked at with ultraviolet light. The grass awns (or seeds) are in the picture at the bottom.

Grass awns are dangerous because they are barbed in only one direction and are very, very good at migrating around the body if they ever get up under the skin. As they travel along they deposit bacteria of various degrees of nastiness. There are many cases of these little buggers entering a wound on the chest, for instance, and then migrating around until they actually end up in the chest cavity causing horrid infection.

The cornea is the clear part of the surface of the eye. It is composed of dozens of layers of cells in a laminar, or onion, type configeration. The cornea is transparent because the thickness of the cells is a very specific measurement (even multiples of the wavelength of visible light) and so light passes right through. In the case of trauma or ulceration of the cornea, it takes on an opaue appearance due to swelling of the cells. This opacity resolves as the swelling resolves.

Since the cornea doesn't have its own blood supply for nutrition (blood vessels wouldn't be transparent so the body choose not to put them there) then it depends on the tear film on the outside and the fluid in the front chamber of the eye from behind. So in the case of damage or ulceration of the cornea, any medications you give must be given frequently or they simply wash away.

In the case of a scratch to the cornea, we assume that it either is or is about to be infected. Again, without blood flow, there are few white blood cells there to help fight the normal exposure to bacteria.

This poor little guy should do fine in the long run. If we can get the infection under control and get the cornea to heal cleanly, we will hopefully only have a thin, nearly transparent scar on the cornea. As long as he doesn't have to read or drive a car, he'll never notice.

AMH