1887

The uveal tract

image of The uveal tract
GBP
Online Access: GBP25.00 + VAT
BSAVA Library Pass Buy a pass

Abstract

The uveal tract is composed of continuous tissue that is anatomically subdivided into the iris, ciliary body and choroid. Pathological conditions that affect the uvea are commonly encountered in ophthalmic practice. This chapter covers a wide variety of conditions that affect the uvea, from normal variations, developmental abnormalities and age-related changes to acquired pathological processes. The anatomy, physiology and immune mechanisms are applicable to both dogs and cats. This chapter focuses on conditions that affect the anterior uvea (iris and ciliary body).

Loading full text...

Full text loading...

/content/chapter/10.22233/9781910443170.chap14

Figures

Image of 14.1
14.1 Illustration of the eye showing the different parts of the uvea. Canine eye showing the location of the uvea and its relative proportions. C = choroid; CP = ciliary process; I = iris; PP = pars plana; T = tapetum. (b, Courtesy of JR Mould). Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.
Image of 14.2
14.2 Normal blue iris of a dog showing the major arterial circle in the periphery (black arrows) and position of the iris collarette at the border between the pupillary and ciliary zones of the iris (red arrow). The posterior iris pigmented epithelium is visible through the thinner pupillary zone of the iris, which therefore appears darker than the ciliary portion.
Image of 14.3
14.3 The blood–ocular barrier. The epithelial and vascular components of the blood–aqueous barrier are shown on the left, and the epithelial and vascular components of the blood–retinal barrier are shown on the right. IBV = iris blood vessel; NPCE = non-pigmented ciliary epithelium; RBV = retinal blood vessel; RPE = retinal pigment epithelium. Drawn by S.J. Elmhurst BA Hons (www.livingart.org.uk) and reproduced with her permission.
Image of 14.5
14.5 Boston Terrier with one blue and one brown iris. The blue eye lacks pigment in the choroid and retinal pigment epithelium, which results in a red fundic reflex. In addition, the blue eye also lacks a tapetum.
Image of 14.6
14.6 Heterochromic iris presenting a partial-thickness coloboma (arrowed). The overlying iris stroma is thin or absent, allowing direct visualization of the darkly pigmented iridal epithelium. Note the red fundic reflex, indicating a lack or paucity of fundus pigmentation and/or tapetal development. (Courtesy of BM Spiess)
Image of 14.7
14.7 Pupillary membrane remnants on the anterior lens capsule of a dog. Note the central location and light brown colouration of the pigment spots (white arrow). Although these pigment spots are a relatively common incidental finding in otherwise normal canine eyes, an iris-to-iris PPM remnant (black arrow) and a nuclear and cortical cataract were also present in this eye.
Image of 14.8
14.8 Iris-to-iris PPM remnants in a dog (arrowed). These strands originate at the iris collarette and not at the pupillary margin. Examination with a slit-lamp may be necessary to ascertain the origin and elevation of the PPM off the iris surface.
Image of 14.9
14.9 Peters anomaly in a cat. The iris strands all originate at the collarette region and have the colour of the normal yellow to light brown iris surface. The iris strands attach to a central corneal defect involving the posterior stroma, Descemet’s membrane and endothelium. (Courtesy of the University of Wisconsin-Madison Comparative Ophthalmology Service)
Image of 14.10
14.10 Free-floating PPM remnants originating at the iris collarette.
Image of 14.11
14.11 Posterior synechiae in a patient with chronic uveitis. Note the black colouration of the synechiae and how they originate at the pupillary margin. A complete cataract and subluxation of the lens (arrowed) have also developed as a result of the chronic uveitis.
Image of 14.12
14.12 Senile iris atrophy. Note the relatively mydriatic pupil, irregular pupillary margin and strand of atrophied iris (arrowed). The hazy fundic reflex is due to nuclear sclerosis affecting the lens.
Image of 14.13
14.13 Iris melanosis in a middle-aged dog. Note the irregularity of the pupillary margin as a result of concurrent iris atrophy. There is unrelated nuclear sclerosis and incipient anterior cortical cataract affecting the lens.
Image of 14.14
14.14 Free-floating, heterogeneously pigmented, iridociliary cysts in the anterior chamber of a dog. These cysts can be transilluminated and the tapetal reflection is observed through the cysts (retroillumination).
Image of 14.15
14.15 Multiple, transilluminating, iridociliary cysts observed through the dilated pupil of a 3-year-old neutered Golden Retriever bitch. The remains of one or more deflated cysts are visible as pigment remnants on the anterior lens capsule (arrowed). (Courtesy of the University of Wisconsin-Madison Comparative Ophthalmology Service)
Image of 14.16
14.16 Radially oriented pigment deposits on the anterior lens capsule of an 11-year-old male neutered Golden Retriever. Note the inferior temporal posterior synechia (arrowed). This appearance is consistent with a diagnosis of ‘pigmentary uveitis’ in the Golden Retriever. (Courtesy of the University of Wisconsin-Madison Comparative Ophthalmology Service)
Image of 14.19
14.19 Slit-lamp image of the left eye of a dog with anterior uveitis. The slit beam is projected from the right towards the left side in this image and focused on the superior iris. Swelling of the ciliary zone of the iris is clearly observed as an elevation of the slit beam (arrowed). The cornea is out of focus (arrowhead). (Courtesy of the University of Wisconsin-Madison Comparative Ophthalmology Service)
Image of 14.20
14.20 Granulomatous uveitis in a 4-year-old male crossbreed dog. Inflammatory nodules are present in the iris (arrowheads). Note the granulomatous upper eyelid lesion (black arrow), conjunctival hyperaemia, perilimbal corneal oedema, corneal neovascularization and the superionasal posterior synechia and pigment remnants on the anterior lens capsule (white arrow). The dog was diagnosed with leishmaniosis.
Image of 14.21
14.21 Anterior uveitis in a dog. A narrow beam of focused condensed light is projected from the right towards the left side in this image and focused on the aqueous flare in the anterior chamber. Note the diffuse scattering of light in the anterior chamber, which is best observed at the edge of the light beam (arrowed). This visible continuous beam of light resembles the appearance of car headlights in fog. The cornea is out of focus (arrowhead). This image was taken in a completely darkened room. (Courtesy of the University of Wisconsin-Madison Comparative Ophthalmology Service)
Image of 14.22
14.22 Bilateral fibrin and blood clots in the anterior chamber of a 10-month-old female European Shorthaired cat. No specific aetiology was identified and the cat was diagnosed with idiopathic uveitis.
Image of 14.23
14.23 Hyphaema in a 12-year-old male neutered Labrador-cross dog. The precipitation of erythrocytes in the ventral anterior chamber is clearly demonstrated by the horizontal demarcation line (white arrow). The cell and protein content caused intense light scattering and reflection in the rest of the anterior chamber, which made observation of iris and lens details and fundus examination impossible. Blood deposits on the anterior lens capsule or corneal endothelium are visible as well (black arrow). This dog was affected bilaterally and was diagnosed with lymphoma. (Courtesy of the University of Wisconsin-Madison Comparative Ophthalmology Service)
Image of 14.24
14.24 Slit-lamp image of a 7-year-old male neutered Soft Coated Wheaten Terrier with anterior uveitis. The slit beam is projected from the right towards the left side in this image and focused on the anterior chamber cells and flare (*). Note the corpuscular nature of the material (cells) within the anterior chamber, resembling floating dust particles in a beam of light. Diffuse light scattering is present as well (flare). The cornea is out of focus (arrowhead). This image was taken in a completely darkened room. Slightly less magnified view taken with the room lights on. Note how much more difficult it is to identify the anterior chamber flare and cells, let alone grade them.
Image of 14.25
14.25 Bilateral hypopyon in a 6-year-old neutered Rat Terrier bitch. Note the horizontal demarcation lines. The rest of the anterior chamber also appears hazy owing to the cell and protein content, as evidenced by the loss of iris detail in both eyes. Small amounts of blood are also visible inferionasally in the anterior chambers. This dog was diagnosed with lymphoma. (Courtesy of the University of Wisconsin-Madison Comparative Ophthalmology Service)
Image of 14.26
14.26 Slit-lamp image of a Domestic Shorthaired cat with anterior uveitis. The slit beam is projected from the left towards the right side in this image and focused on the cornea. Under direct illumination in the slit beam, keratic precipitates (KPs) are visible as whitish deposits on the inferior, endothelial side of the cornea. With retroillumination (on the right-hand side of the slit beam) the KPs take on a grey–brown colour. The cat was found to be FIV-positive. Appearance of KPs on the inferior cornea with diffuse illumination. With direct illumination (pupil as the background) the KPs are a yellow to tan colour; with retroillumination (iris as the background) they appear grey–brown. (Courtesy of the University of Wisconsin-Madison Comparative Ophthalmology Service)
Image of 14.27
14.27 Pupil seclusion and iris bombé in an 8-year-old male neutered Domestic Shorthaired cat with chronic uveitis. Front view. Side view.
Image of 14.28
14.28 A pre-iridal fibrovascular membrane (PIFVM) covering the anterior iris surface (rubeosis iridis) and anterior lens capsule in a 4-year-old female neutered European Shorthaired cat with chronic uveitis caused by an old corneal perforation. Note the irregular partially circumferential course of the blood vessels and blood vessels crossing from the iris surface on to the lens capsule (arrowed). The perforation wound had healed and left a corneal scar (arrowheads). Histopathological cross-section of the iris and cornea of a dog with a thick PIFVM (asterisk and arrowheads) covering the anterior surface of the iris and causing ectropion uveae (arrowed). A history of ocular trauma was present. (Courtesy of Dr RR Dubielzig, Comparative Ophthalmic Pathology Laboratory of Wisconsin)
Image of 14.30
14.30 In the hands of a reasonably experienced examiner, small handheld slit-lamps, whilst inferior to larger portable slit-lamps favoured by veterinary ophthalmologists, can be used by practitioners to perform a good anterior segment examination. (Courtesy of K Sherman) Slit-lamp biomicroscopes provide the examiner with a binocular view and superior magnification. Advanced diagnostic training is needed to take full advantage of this instrument.
Image of 14.31
14.31 Slit-lamp image of the normal left eye of a 9-year-old male neutered Domestic Shorthaired cat, demonstrating the appearance of the anterior segment: the convex, bright corneal reflex (white arrow), completely dark anterior chamber (*) and the somewhat dimmer, convex anterior lens capsular reflex (black arrow). The slit beam is projected from the right towards the left side in this image. (Courtesy of the University of Wisconsin-Madison Comparative Ophthalmology Service)
Image of 14.34
14.34 Septic keratitis and secondary hypopyon in a 9-year-old male neutered Shih Tzu. A white cell precipitate is clearly visible in the inferior anterior chamber. The edge of the corneal ulcer shows signs of melting (arrowed). infection was identified on clinical microbiology.
Image of 14.35
14.35 Endophthalmitis, posterior synechia formation, iris bombé and secondary glaucoma in the right eye of a 6-year-old male neutered Vizsla with blastomycosis. Note the yellow appearance of the pupil, due to chorioretinal granulomas and complete retinal detachment. The eye was enucleated as soon as the systemic condition of the dog had been stabilized.
Image of 14.36
14.36 Lens-induced uveitis in a dog with a primary cataract. Note the conjunctival hyperaemia and peripheral corneal neovascularization (red eye), the mild perilimbal corneal oedema and the pigment rests on the anterior lens capsule due to previous iris-to-lens adhesions. (Courtesy of the University of Wisconsin-Madison Comparative Ophthalmology Service)
Image of 14.37
14.37 Labrador Retriever with uveodermatological syndrome before overt onset of the disease. Years later, depigmentation of the fur and eyelid margins is obvious. Almost 6 years have passed between the first presentation and this recheck, during which almost complete pigment loss was observed. Note the progressive depigmentation around the edges of the nasal planum when comparing (b) and (c). At this time the dog had lost vision as a result of uveitis-induced cataracts. The uveitis was fairly well controlled with systemic corticosteroid therapy.
Image of 14.38
14.38 Lipid-laden aqueous in a hypothyroid 5-year-old male neutered crossbreed dog. Slit-lamp image of lipid-laden aqueous in a 5-year-old male neutered Cavalier King Charles Spaniel. The slit beam is projected from the left towards the right side in this image and focused on the dense, milky, lipid flare in the anterior chamber. Note the convection currents in the anterior chamber, caused by an upward movement of warmer aqueous close to the lens and a downward movement of cooler aqueous on the corneal side.
Image of 14.40
14.40 Traumatic rupture of the globe with extrusion of ocular contents (black material at the medial canthus). The eye was subsequently enucleated. (Courtesy of the University of Wisconsin-Madison Comparative Ophthalmology Service)
Image of 14.41
14.41 Perforation of the temporal cornea with protrusion of iris through the corneal defect in a young Shih Tzu.
Image of 14.42
14.42 Iris stromal haemorrhage secondary to immune-mediated thrombocytopenia in a Great Dane.
Image of 14.44
14.44 Bilateral hyphaema associated with multicentric lymphoma in an 11-year-old American Staffordshire Terrier. Close-up view of the right eye. (Courtesy of the University of Wisconsin-Madison Comparative Ophthalmology Service)
Image of 14.45
14.45 Ocular melanosis in a Cairn Terrier. The iris is diffusely hyperpigmented and thickened. Pigment accumulation within the sclera results in the characteristic black patches. Pigment also accumulates in the choroid, leading to infiltration of the tapetum. The fundic image is somewhat blurred owing to nuclear sclerosis.
Image of 14.46
14.46 Melanocytoma involving a large portion of the superior iris, leading to pupillary distortion. (Courtesy of BM Spiess) Ciliary body melanocytoma extending into the sclera and temporal iris.
Image of 14.47
14.47 A ciliary body adenoma visible as a pink mass protruding into the pupil.
Image of 14.48
14.48 Appearance of the iris in a young Labrador Retriever that had undergone diode laser photocoagulation twice as treatment for a presumed iris melanocytoma involving the inferionasal quadrant in an otherwise comfortable and sighted eye. Note the mild dyscoria and iris atrophy at the 3 o’clock position. Two small iris cysts are also present.
Image of 14.49
14.49 Multiple smooth-surfaced iridociliary cysts are visible behind the pupil in this cat.
Image of 14.50
14.50 Multifocal iris melanosis in a middle-aged cat. (Courtesy of the University of Wisconsin-Madison Comparative Ophthalmology Service)
Image of 14.52
14.52 Chronic lymphoplasmacytic uveitis in a 15-year-old cat. The branching mid to far peripheral blood vessels with an irregular course (arrowheads) are part of a pre-iridal fibrovascular membrane covering the anterior iris surface (rubeosis iridis). Note also the inflammatory nodules in the iris (arrowed). A clot of fibrin and blood is present in the ventral anterior chamber. Histopathological cross-section of the iris, drainage angle and sclera of a cat with lymphoplasmacytic uveitis and secondary glaucoma. The clinically conspicuous lymphoplasmacytic inflammatory iris nodules are clearly visible (arrowheads). An inflammatory cell infiltrate fills and obstructs the drainage angle structures (arrowed). (Haematoxylin and eosin stain; original magnification x40) (Courtesy of Dr RR Dubielzig, Comparative Ophthalmic Pathology Laboratory of Wisconsin)
Image of 14.53
14.53 Vitreal haemorrhage in a cat with systemic hypertension.
Image of 14.54
14.54 A thorn lodged in the anterior chamber. There was surprisingly little discomfort and inflammation. Note the fibrin clot adhered to the intraocular portion of the thorn (arrowed). Extracted thorn.
Image of 14.55
14.55 Different presentations of feline diffuse iris melanoma. The right iris has developed a slightly darker shade. Close-up view of the eye in (a) demonstrating the ‘velvety’ appearance of the iris surface. The left iris in this cat is darkly pigmented. Close-up view of the eye in (c) showing pigmented cell deposits on the anterior lens capsule (see also Figure 14.56 ).
Image of 14.56
14.56 Slit-lamp image of melanoma cells within the anterior chamber of a cat. (Courtesy of BM Spiess)
Image of 14.57
14.57 Ocular lymphoma in a cat. Note the pink nodular mass, iris neovascularization (rubeosis iridis), fibrin and inferior keratic precipitates. (Courtesy of BM Spiess)
Image of 14.58
14.58 A feline iridociliary adenoma seen as a pink mass displacing the temporal iris and distorting the pupil.

More like this

/content/chapter/10.22233/9781910443170.chap14
dcterms_title,dcterms_description
-contentType:Journal
5
5
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error