Dr. Tom Sullivan, a veterinary ophthalmologist at Animal Eye Clinic in Seattle, answers this week’s questions about eye problems in aging dogs. It is part of our continuing series about the health issues facing senior dogs.
Question: Eye issues can be prevalent in senior pets and something owners often ignore or underestimate. Why are seniors particularly vulnerable to eye problems, and what are the most common eye issues you see in your older patients?
Answer: Seniors are more likely to have eye problems for a few reasons. First, some disorders are a result of aging and wear and tear. Cataracts, retinal degeneration, for example, are often age-related degenerative conditions.
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Second, older animals have had more opportunity to sustain injury to the eyes, which can lead to long-term complications like glaucoma.
Lastly, some eye diseases are a result of systemic conditions — such as diabetes, high blood pressure, cancers — all of which are more common in the elderly.
Nuclear Sclerosis: This is a normal change seen in aging lenses. The lens sits behind the iris — the colored part of the eye. The pupil is simply a hole in the iris through which we see. The lens is transparent, so we normally don’t see it when we look at our dog.
The lens continues to grow throughout life and forms rings similar to the growth of a tree. Instead of increasing in diameter, each new ring compresses the central part of the lens more and more. As more and more rings compress that nucleus into a smaller and smaller ball, the compressed lens proteins lose some transparency and begin to reflect light approaching from certain angles.
This reflected light makes the pupil appear cloudy when viewed from the exterior but interferes very little with vision.
This is the cloudy appearance seen in older dogs, and it is a normal change. It generally begins at about 7 years of age, but it doesn’t tend to become noticeable until 10 or 11. If you have a dog 10 or older with cloudy looking eyes but no signs of poor vision, it is very likely this.