has a 9-year-old Basset hound named Hank who seems to be
having trouble seeing. Over the past three months or so
Hank seems tentative when walking, especially in
unfamiliar areas. The problem seems worse at night. When
Alan has looked at Hankís eyes, he has noticed a blue
color and wondered if this might be a cataract.
I thank you for the question and especially for the
excellent detail you provided about Hankís condition.
First of all it is important to know if the blue color
that Alan is seeing is from the outer portion of the
eye, the cornea, or deeper within the eye, the lens. If
there are no other associated problems with Hankís
eyes, it is not likely to be a corneal problem only
because there are usually other symptoms when this
structure is involved. Older corneal scarring can leave
a bluish cast to the eye, but this has been noticed for
only about three months so a corneal disease is less
this discussion, I am going to assume that the blue
color in Hankís eyes is coming from changes in his
lenses within his eyes. The lens in the eye is a very
specialized structure, normally clear, that is
responsible for focusing what is seen onto the retina.
The lens is similar in function to the lens of a camera.
viewed image passes through the lens and, depending on
the distance from the eye, the lens changes shape from
rounder to more oval or more oval to rounder to focus
the image onto the retina in the back of the eye.
I previously stated, the lens is a very clear structure
but there are changes within its structure that can
cause a coloring of the tissue. By far the most common
color change seen is one from clear to various shades of
blue. As Alan mentioned, cataracts are a possibility.
cataract is any opacity; i.e. decreased
"clearness" to the lens, which prevents normal
vision. When this process within the lens first begins,
it is possible to see an area of opacification within
the lens, but vision is not usually impaired. The
process can stop at any point but is often progressive,
eventually rendering the entire lens opaque and
can be inherited, as there are certain breeds of dogs
that show higher incidence of cataracts including
American cocker spaniels, golden retrievers, miniature
schnauzers, old English sheepdogs and poodles. Some
forms of cataracts can start from birth, called juvenile
cataracts, while others develop later in life.
cataracts can develop as a secondary result of an
underlying disease process. The most common example is
cataracts associated with diabetes mellitus. This
disease should always be considered and ruled out with
any case of diagnosed cataracts in our companions.
possible cause of a blue color to the lenses is a
process called lenticular sclerosis. This is the gradual
age-related hardening of the lens that begins to occur
around middle age in virtually all types of companions.
It usually starts in the central portion of the lens,
which starts to turn a grayish blue. It is not a
cataract although is commonly diagnosed, even by
sclerosis still allows for vision whereas cataracts
often cause blindness. We know in humans with lenticular
sclerosis that visual acuity, their ability to focus, is
impaired with lenticular sclerosis. These people often
wear bifocals. Weíve yet to be able to fit bifocals to
you notice your companionís eyes developing a blue
color bring them to your veterinarian for a thorough
examination. It is generally very straightforward to
diagnose, and as a result, you can discuss treatment
the case of cataracts, your veterinarian can refer you
to a board-certified ophthalmologist for specific
treatments available. This condition, especially when it
occurs in younger to middle-aged companions, is very
correctable. Often total vision can be restored. In the
case of lenticular sclerosis, there is no treatment.
Alas, these companions will likely have to buy their
books in large type.