Page 1317 - Problem-Based Feline Medicine

64 – THE CAT WITH ABNORMAL GLOBE POSITION OR SIZE 1309

DECREASED GLOBE SIZE OR PROMINENCE
WHERE?

GLOBE
DEGENERATIVE
● Pthisis (p 1315)
Reduced globe size occurs secondary to a known history of severe trauma, chronic intra-ocular
inflammation or hemorrhage. Unusual in cats.
ANOMALY

● Microphthalmos (p 1316)
Rare in cats. Appears as small eye with small corneal dimensions sometimes and associated with
other ocular defects, e.g. cataract.
TRAUMA
● Collapse of the globe* (p 1315)
Small globe and signs of aqueous leakage (wetting of the skin and haircoat around the eye), which
occurs in association with rupture of the cornea or sclera.

WHERE:

ORBIT
DEGENERATIVE

● Enophthalmos secondary to orbital fat loss or muscle wastage** (p 1314)
Bilateral, non-painful, caudal displacement of the globe occurs associated with generalized muscle
wastage and weight loss. The third eyelid is prominent.

INTRODUCTION WHAT?

The most common causes of abnormal globe posi-
MECHANISM? tioning or size in the cat are:
● Cranial displacement (exophthalmos) from
A globe which appears to be more prominent may be
orbital cellulitis or orbital neoplasia.
either enlarged (buphthalmic) or a normal-sized globe
● Increased size (buphthalmos) from chronic
which is abnormally positioned, usually displaced cra-
glaucoma.
nially (exophthalmic). Likewise a globe which is less
● Caudal displacement (enophthalmos) as a result of
prominent may be so because it is shrunken (pthisis) or
shrinkage of orbital tissue related to loss of orbital fat.
it may be a normal-sized globe which is positioned
● Reduced size (pthisis) from shrinkage of the globe
more caudally or deeper in the orbit (enophthalmic).
due to intractable inflammation causing low intra-
ocular pressure or leakage due to a persistent
corneal or scleral defect.
WHERE?
Unilateral prominence or enlargement can best be
Globe.
appreciated by comparing with the opposite eye espe-
Orbit. cially from the dorsal aspect.