Uvea

Chapter 7 Uvea

INTRODUCTION

The internal vascular layers of the eye—the iris and ciliary body in the anterior segment and the choroid of the posterior segment—make up the uvea. These layers are composed of dense networks of blood vessels of various sizes and have varying degrees of pigmentation. Consequently, the pathology that affects these layers reflects their vascular basis—inflammation, hematogenous spread of infectious agents, and neoplasms. The most significant lesions of the uvea are inflammatory. Various congenital uveal abnormalities, often hereditary, such as colobomas and persistent pupillary membranes, pigmentation variations, uveal cysts, and tumors, are also frequently seen in small animal practice.

Figure 7-1 Normal cat iris with major arterial circle.

Figure 7-2 Aniridia in a dog.

Figure 7-3 Iris coloboma extending nasally in an Australian shepherd. A coloboma is a congenital defect—in this case, in the nasal iris—that involves the sphincter muscle. Iris colobomas are hereditary in this breed and can be associated with multiple ocular anomalies.

Figure 7-4 Iris coloboma extending nasally in the pupil of an Australian shepherd.

Figure 7-5 Australian shepherd with dyscoria. Dyscoria is abnormally shaped pupil; usually a dyscoric pupil is not round and is eccentric in the iris. The condition is hereditary in Australian shepherds and is associated with multiple ocular anomalies.

Figure 7-6 Iris coloboma.

Figure 7-7 Iris coloboma extending nasally and heterochromia iridis in an Australian shepherd. This coloboma involves the iris dilator muscle.

Figure 7-8 Iris-to-lens persistent pupillary membrane (PPM). PPMs are remnants of the vasculature that fills the anterior chamber during fetal development of the eye. Iris-to-lens PPMs are usually associated with cataracts where the PPM touches the lens capsule.

Figure 7-10 Iris-to-lens PPM. Same dog as in Figure 7-9.

Figure 7-9 Iris-to-lens PPM showing attachment of the PPM to the iris collarette.

Figure 7-11 PPM: iris to lens and iris to iris.

Figure 7-12 Iris-to-lens PPM in a Doberman pinscher.

Figure 7-13 PPM: iris to lens capsule.

Figure 7-14 PPM remnants on the lens capsule. Linear opacity is a hair on the cornea. These small pigment deposits on the anterior lens capsule are seen in many dogs and rarely cause any vision-related or other problems. The heritability of these types of deposits is unknown.

Figure 7-15 Iris-to-lens PPM with associated central cataract in a cat.

(Courtesy Dr. Robert Playter.)

Figure 7-17 Same cat as in Figure 7-16 at a later date. The PPMs have decreased.

Figure 7-16 Young kitten with lipoprotein lipase deficiency and lipemia with patent PPMs and lipemic iridal vessels.

Figure 7-18 Iris-to-cornea PPM in a cat. Corneal edema may be present where the PPM touches the cornea.

Figure 7-19 PPMs in a cat. Vascular remnants on the anterior lens capsule.

Figure 7-20 Heterochromia iridis. A marked reduction in pigmentation results in a blue color of the iris.

Figure 7-21 Heterochromia iridis. Heterochromia iridis is a condition in which a difference in color between the irides or in different parts of the same iris exists.

Figure 7-22 Heterochromia iridis in an Australian shepherd.

Figure 7-23 Subalbinotic iris.

Figure 7-24 Heterochromia iridis.

Figure 7-25 Heterochromia iridis.

Figure 7-26 Heterochromia iridis.

Figure 7-27 Iris dilator muscle atrophy.

(Courtesy Dr. Robert Playter)

Figure 7-28 Iris dilator muscle atrophy.

Figure 7-29 Iris sphincter and dilator muscle atrophy; nuclear sclerosis.

Figure 7-30 Thinned iris stroma (atrophy) in a blue-eyed cat.

Figure 7-31 Thinned iris (atrophy) near the pupillary margin in a cat.

Figure 7-33 Close-up of cyst shown in Figure 7-32.

Figure 7-32 Nonpigmented cyst arising from the ciliary epithelium in a dog.

Figure 7-34 Free-floating iris cyst in anterior chamber in a dog; note the transillumination of the tapetal reflex through the cyst. These cysts must be distinguished from iris melanomas and rarely need treatment.

Figure 7-35 Free-floating iris cyst in the anterior chamber of a Boston terrier. Note the transillumination of the tapetal reflex. An immature cataract is incidentally present.

Figure 7-36 Iris cysts at the pupillary margin and in the anterior chamber in a 7-year-old Irish wolfhound.

Figure 7-37 Multifocal small iris cysts at pupil margin of a dog with a cataract. Lipid keratopathy also is present.

Figure 7-38 Iris cyst in a 4-year-old cat.

Figure 7-39 Iris cysts at the pupil margin of a cat.

Figure 7-40 Iris and ciliary body cyst visible through the pupil of a cat.

Figure 7-41 Iris cysts in a cat.

Figure 7-42 Nevus in the iris of a dog; the differential diagnosis is melanoma. A nevus is also called a freckle. Nevi are acquired lesions that are usually flat with the iris surface.

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Tags: Color Atlas of Canine and Feline Ophthalmology

Jul 31, 2016 | Posted by admin in INTERNAL MEDICINE | Comments Off

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