Eye Continued: Age and color...
Eye Continued: Age and color...
Age and Color Related Problems
This will be the last of what has developed into a long series of articles on the eye. If you have an interest in reading all of them, call our office and we will send them to you.
There are a few eye problems we see more often in the older horse and in those with white faces (bald faced, as we say). As the horse ages changes occur to the content of the lens. The lens will start to harden into cataracts. These look like ice and are easiest to see in a dark room. The lens will relax to let in more light, with the use of a flashlight we can see these large ice-filled structures. These changes take place in all horses. The changes may occur sooner in some than others, depending on where they lived in their early years. Southern horses will generally development cataracts earlier than their northern cousins. Horses with bald faces, or with just white around the eye, certainly will develop them early.
Cataracts can be removed if they interfere with Dobbin’s vision. They may be a factor in the performance horse because of the need to react quickly. However, in most horses the change in the lens has been so gradual they have become somewhat used to seeing the outline of objects blurred much, as many of us are trying to adapt to print becoming blurred. If the cataracts are a problem they can be removed and a clear lens put in their place.
We often are asked about the dark object along the top (and less often along the bottom) of the partition between the front and the back of the internal chambers of the eye. It looks like moss or mold growing along the edge and hanging down over the lens. The size varies between horses. It is the granule iridus (indicating someone who studies anatomy has seen it and named it). Other than to stimulate curiosity (and occasionally concern) it has no function. Look deep into your horse’s eye and see if it has these structures. They sure look out of place!
The bald face horse will usually be presented to us with conjunctivitis earlier in the spring than other horses. Whatever irritation other horses experience, the bald face horse will have it worse. In many horses, bright sunlight is the cause of tearing. Adding reflection from snow makes it worse, as does irritation from dust, pollen, long grass, etc. In the horse with white around the eyes, the effect of the sun is greater due to added reflection from white hair and skin. In addition to enduring the direct sunlight, they also have the reflected sun. One simple approach is to darken the area around the eyes with shoe polish or some other dark stain. This will absorb the sunlight and reduces its reflected affect. As the days become longer into summer, the horse may need a mask.
With continuous irritation of the eye, scabs may form along the eyelids. We think of these as being pre-cancerous. If they are ignored, they will become larger and erode away the tissue of the lid. They must eventually be removed. If they become very large, the surgical removal of damaged tissue will result in a gap in the eyelid. The lids will be unable to close completely, allowing irritants to contact the eye. This leads to further irritation. As you can see, it is better to treat and/or correct this problem early.
We have had a very thorough discussion of the eye. By now you have probably heard more about the eye and its problems than you ever wanted to know. If there are other topics you would like to discuss, or if you have questions, please forward them to us. We will make every effort to cover them and periodically answer questions that arrive. This column is for information, so please feel free to use it.
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