Page 1212 - Problem-Based Feline Medicine

1204 PART 15 CAT WITH EYE PROBLEMS

associated with the retina such as detachment, and rup-
HYPERTENSIVE RETINOPATHY***
ture of the sclera, as well as hemorrhage in the orbit.
Radiology may be useful to check the orbital bones for Classical signs
signs of fracture.
● Sudden blindness in an old cat.
● Dilated pupils, non-responsive or poorly
responsive to light.
THE RED EYE CAUSED BY RED ● Retinal hemorrhages mainly along the
REFLECTION FROM THE RETINA major blood vessels with hemorrhage in
the vitreous.
THE TIGROID FUNDUS*** ● The retina may be detached and difficult to
visualize clearly.
Classical signs
See the main reference on page 1171 for details (The
● A red fundus reflex is seen frequently in Blind Cat or Cat With Retinal Disease) and also page
color-diluted cats. 1202 (The red vitreous).
● Seen in cats with a blue iris such as
Siamese and Color Points. Clinical signs

Typically appears as acute-onset vision loss in an old
cat.
Clinical signs
Pupils are dilated, and non-responsive or poorly
The red reflex is often seen by owners using flash photog- responsive to light. Signs are usually bilateral.
raphy as a “red eye”.
Affected eyes appear slightly cloudy and focal red areas
In cats the red reflex is frequently misdiagnosed as of hemorrhage are visible through the pupils.
retinal hemorrhage.
Retinal hemorrhages occur mainly along the major
The appearance of a red fundus reflection can be nor- blood vessels, with hemorrhage in the vitreous.
mal in a color-dilute cat. Cats with color dilution have
When the retina is detached, the retinal blood vessels
no pigment in the retinal pigment epithelial cells.
are not clearly in focus with an ophthalmoscope. The
As a result, the blood vessels of the choroid are seen
retina can be seen ballooning into the vitreous, and
clearly against the white background of the sclera. The
appears as a thin veil of pale tissue.
blood vessels appear in a tigroid pattern (called tigroid
fundus), and can give a striking red reflex when seen
through the pupil in certain light. Where there is no Diagnosis
tapetum, the whole of the fundus will appear red.
Diagnosis is based on the clinical presentation of acute
Where there is a tapetum, then only the non-tapetum
vision loss in an older cat, the finding of hemorrhage
will appear red.
adjacent to major vessels in the retina, and systolic
Occurs in cats with a blue iris such as Siamese and blood pressure > 160 mmHg.
Color Points.
Blind cats usually have a total retinal detachment in
both eyes. The retina cannot be visualized through the
pupil with an ophthalmoscope, and a thin veil of pale
Diagnosis tissue can be seen bulging into the vitreous.

Diagnosis is based on signs. On ophthalmic examina- Hyperthyroidism and chronic renal disease need to
tion the eyes are normal, with the typical tigroid vas- be ruled out with diagnostic tests, and thoracic radio-
cular pattern. The breed and blue iris color are graphs or cardiac ultrasound may be useful to detect
indicators of a tigroid fundus. cardio-megaly.