Page 1279 - Problem-Based Feline Medicine

61 – THE CAT WITH A CLOUDY EYE 1271

Signs of uveitis or history of past uveitis indicate the
DISEASES CAUSING A CLOUDY LENS
origin of the cataract. See page 1303 (The Cat With
Abnormal Iris Appearance).
CATARACT SECONDARY TO INFECTIOUS The eye should be checked for glaucoma by measuring
UVEITIS**
the intra-ocular pressure.
Classical signs
Treatment
● Cloudy lens, unilateral or bilateral.
● Frequently only unilateral. Cataract surgery can be done if the inflammation has
● Poor vision if bilateral. Iris may be been controlled.
distorted from posterior synechia. ● It is prudent to do a diagnostic work-up for sys-
● Iris may show fibrovascular membranes on temic diseases that cause uveitis prior to doing
surface. surgery. See page 1199 (The Blind Cat or Cat With
● History of chronic uveitis caused by Retinal Disease) and page 1304 (The Cat With
infectious agent such as toxoplasmosis or Abnormal Iris Appearance).
fungal disease. ● Check the eye for retinal detachment with ultra-
sound prior to surgery.
● An electroretinogram is indicated to ensure that
Pathogenesis
the eye has normal retinal function prior to surgery.
Inflammation in the eye results in changes to the lens
nutrition and accumulation of toxic products in the eye
which results in death of cells. This will cause a cloudy
NUCLEAR SCLEROSIS AND SENILE
lens (cataract).
CATARACT**
Cataract is often associated with chronic uveitis caused by
infectious agent such as toxoplasmosis or fungal disease. Classical signs
● Milky appearance of lens in cats older than
Clinical signs
10 years of age.
The lens appears cloudy due to the formation of a cor- ● Cats are usually visual and leading a
tical cataract. normal lifestyle.
● The fundus can be seen clearly with an
The cataract may be unilateral or bilateral, but is
ophthalmoscope.
more often unilateral. Vision is poor if bilateral.
Other signs of uveitis will be present such as aqueous
flare and fibrovascular membrane growth on the iris. Pathogenesis
The iris may have a darker color than the opposite eye,
Nuclear sclerosis is a normal aging process in the lens
or have changes in contour due to adhesions of the iris
which starts in animals from about 8 years of age and is
to the anterior lens capsule (posterior synechia).
evident by 10 years.
There may be changes in the cornea such as edema or
Lens fibers are produced throughout life, but the lens
scarring, with or without superficial vascularization.
does not increase in size. Therefore, the fibers in the
Hypopyon or keratic precipitates may be evident. center become thinner and pack closer together
causing a slight opacity, termed sclerosis. As the lens
Some cats develop secondary glaucoma.
ages further some of these fibers may break-down and
then a nuclear cataract develops. In very old cats, the
Diagnosis
nuclear cataract may become quite dense with second-
A tentative diagnosis is based on the signs of a cloudy ary changes in the surrounding cortex leading to a
lens or cataract. mature cataract.