Page 1294 - Problem-Based Feline Medicine

1286 PART 15 CAT WITH EYE PROBLEMS

Prognosis FELINE LEUKEMIA VIRUS

Effects of prolonged deficiency are only partially INFECTION/FELINE SPASTIC
reversible, and supplementation is of no value where PUPIL SYNDROME*
there is advanced retinal degeneration with blindness.
The appearance of the lesions evident at time of diag- Classical signs
nosis will remain the same, even though the ERG signs
● History of variable pupil behavior with
associated with rod degeneration may reverse.
pupils at different times alternating
between miotic or dilated, in one or both
eyes, over weeks to months. Intervening
DYSCORIA ASSOCIATED WITH IRIS periods of normality with equal pupils.
SYNECHIA OR PROLAPSE INTO ● Normal vision.
A CORNEAL WOUND* ● Pupils may fail to dilate or incompletely
dilate in semi-darkness.
Classical signs
● Pear- or tear-shaped pupil, with adhesion
Pathogenesis
of the acute angle of the tear to the lens
capsule or to a traumatic defect in the Viral neuritis is caused by feline leukemia virus
cornea. (FeLV) and affects the parasympathetic and/or sympa-
thetic efferent fibers to the iris.

Clinical signs Clinical signs
Pear- or tear-shaped pupil, with the acute angle of the Cats retain vision, but the pupils fail to dilate, or
tear sticking to either the lens capsule, or to a trau- incompletely dilate in semi-darkness.
matic defect in the cornea.
The history often reveals paradoxically varying pupil
The abnormal shape is often accentuated by stimulating behavior, with pupils alternating between miotic or
the papillary light reflex with a bright light. dilated, in one or both eyes in the weeks to months prior
to presentation. There may have been intervening peri-
ods of normality with equal pupils.
Diagnosis Other ocular signs may be seen, for example, FeLV-
associated lymphoma involving the iris, may cause
Diagnosis is based purely on careful examination of
swelling and hemorrhage of the iris surface. See main
the eye by focal light examination or slit lamp bio-
reference on page 1300 for more details (The Cat With
microscopy.
Abnormal Iris Appearance).
Diagnosis
Treatment
Diagnosis is based on the history of an intermittent,
Treatment is usually either medical or surgical.
bizarre, inexplicable variation in pupil response.
● Medical treatment with mydriatics such as atro-
pine, mydriacyl or 10% phenylephrine will some- Supportive evidence is based on positive testing for
times pull the iris away from the lens or cornea, if FeLV.
used in the very early stages.
● Surgical repair by a veterinary ophthalmic sur-
Treatment
geon is recommended. Repair the corneal laceration
and replace the iris and tamponade away from the There is no treatment for this condition. This syn-
corneal wound, using viscoelastics. drome is thought to have a very poor prognosis with