Page 1267 - Problem-Based Feline Medicine

61 – THE CAT WITH A CLOUDY EYE 1259

its nutritional requirements. Disturbance to the nutri- structures. For example, the change in the structure of
tion of the lens will result in death of lens fibers and the crystallins in the lens results in cataract formation.
development of a cataract. ● Accumulation of protein and cells in the
aqueous humor causes a cloudy aqueous called
Genetic cataract is rare in the cat.
hypopyon.
Most cataracts in cats are secondary to disease ● On rare occasions lipid may be seen in the aqueous
processes within the eye such as uveitis or neoplasia. (aqueous lipid) forming a very cloudy eye.
● Leakage of cells and protein into the vitreous from
Lens fibers in the nucleus become slightly opaque with
inflammation of the ciliary body and/or choroid
age. This is known as nuclear sclerosis and may be
causes a cloudy vitreous.
seen from about 8 years of age. This is not a true
cataract as the fibers are viable and the eye is usually The most common causes of corneal cloudiness are
visual. With age, the nuclear fibers may die, so nuclear from inflammation associated with herpesvirus ker-
sclerosis may develop into a nuclear cataract. atitis or eosinophilic keratitis, or from trauma result-
ing in edema, cellular infiltrates, ulcerative keratitis,
and/or scarring or corneal sequestrum.
Cloudy vitreous
The most common causes of anterior chamber
The vitreous is a living tissue (mainly mucopolysac- cloudiness are inflammation from infectious agents
charide; also called glycosaminoglycans) that fills the such as Toxoplamsa gondii, Cryptococcus, other sys-
space between the retina, ciliary body and lens. temic fungi, feline infectious peritonitis virus, feline
leukemia virus or from neoplasia.
Inflammation or hypertension of the inner retinal blood
vessels will allow protein and white/red blood cells to The most common causes of lens cloudiness are from
leak into the vitreous causing “vitreous flare”. This nuclear sclerosis or cataract secondary to infectious
may present as a cloudy eye behind the pupil. uveitis or trauma.
Inflammation of the choroid (posterior uvea) leads to The most common cause of posterior chamber cloudi-
leakage of protein and blood cells into the outer retinal ness is from systemic hypertension.
space leading to a serous retinal detachment. Retinal
detachment can present as a cloudy eye behind the pupil.
DISEASES CAUSING A CLOUDY
Vitreous degeneration is rare in the cat. CORNEA

WHERE? FELINE HERPESVIRUS-1 KERATITIS***
Disease affecting the cornea, anterior chamber, lens
Classical signs
or vitreous may result in a cloudy eye.
● FHV-1 keratitis is primarily a disease of
Decide which of the media have become cloudy and go
older cats.
to that part of the text for greater detail.
● Frequently unilateral but may be bilateral.
● Shallow irregular ulceration (geographic
ulcer) often with superficial vascularization
WHAT?
and edema.
Cloudiness of cornea, anterior chamber, lens or vitre- ● History of acute episodes followed by
ous may be caused by: quiescent periods.
● Infiltrates of inflammatory cells or infusion of
tissue fluid (edema), which produces swelling of See main references on pages 1212, 1237 for details
the corneal stroma, will result in a cloudy cornea. (The Cat With Ocular Discharge or Changed Conjunctival
● Alteration of the cellular matrix in the cornea Appearance, The Cat With Abnormalities Confined to
and lens causes a change in the refractive index, the Cornea) and page 7 (The Cat With Acute Sneezing
because of changed chemical properties of these or Nasal Discharge).