Ophtho2- Uvea

vascular tunic

iris, ciliary body, choroid

the iris

• regulates the amount of light entering the posterior portions of the eye
• blood aqueous barrier

• anterior segment= everything in front of the lens
• posterior segment= behind the lens (vitreous, choroid, retina)

• anterior chamber= in front of the iris
• posterior chamber= behind the iris
• [both are within the anterior segment]

• sphincter muscle (smooth muscle under involuntary parasympathetic control)
• dilator muscle (smooth muscle under involuntary sympathetic control)

parasympathetic control from CN III

parasympatholytic agents; topical Tropicamide or atropine

sympathetic denervation of the eye--> miosis, ptosis, enophthalmos, prolapsed third eyelid, ocular hyperemia, (horses only) unilateral sweating

aka granula iridica; in herbivores, these are the extension of the posterior epithelium into the pupil and appear as pigmented, irregular masses; normal finding

iridocorneal angle

ciliary epithelium--> between the iris and the lens--> pupil--> anterior chamber--> iridocorneal angle--> trabecular meshwork--. scleral venous plexus

pars plicata (superior/ dorsal), pars plana (inferior/ ventral)

posterior to the iris

parasympathetic; contraction

• it gives rise to ciliary processes, which produce aqueous humor
• blood-aqueous barrier
• accommodation

2 layers of epithelium; blood-aqueous barrier; aqueous flare

lenticular zonules; attach to the lens, so when the ciliary body contracts, tension on the zonules is relaxed, allowing the lens to thicken [accommodation]

• passive filtration
• diffusion
• active secretion- under the control of carbonic anhydrase

lens luxation.

in the posterior portion of the uvea, from the ciliary body to the optic nerve.

• provides nutrition for the outer portions of the retina (rods and cones) in dogs, cats, and cows; provides nutrition to the entire retina in horses
• cools the highly metabolically active retina

• shiny part of the choroid (in the vascular tunic) that reflects and amplifies light, allowing animals to see in the dark
• cellular in carnivores and fibrous in herbivores

tapetal hyperreflection- tapetum appears much brighter than normal

pigmented

• intraocular pressures taken
• Normal 10-20mmHg
• Glaucoma > 30mmHg
• Anterior Uveitis <7-10mmHg

• congenital hereditary (autosomal recessive in basenjis)
• remnants of fetal iridal vascular arcades, which originate from the collarette zone of the iris 
• fail to regress
• attach to corneal, iris, or lens
• must r/o synechiae

none

• part or all of the iris stroma lacks pigment, resulting in a variation of color within or between the irises
• associated with dilute coat color (blue merle, siamese, harlequin)

alone it has no significance, but it can be associated with other ocular or systemic abnormalities (deafness, blindness)

• a notch defect in the iris, usually in the inferonasal portion of iris
• must differentiate from iris atrophy

acquired; dogs, cats, horses

cystic accumulation of aqueous humor within a layer of the posterior iris or ciliary body epithelium; can be attached or break free and float around

a cyst allows light to pass through it (transilluminates), while a melanoma mass will not

none (benign neglect), laser ablation, irrigation/ aspiration

they cause increased intraocular pressure

small breed old dogs; coloboma

uveitis or glaucoma

decreased PLR; differentiate it from neurologic causes of decreased PLR

it's not

• miosis
• aqueous flare (continuous beam of light from the cornea to the lens)
• redness
• photophobia
• pain - epiphora, blepharospasm, rubbing eyes
• keratic precipitates- accumulations of protein and mononuclear cells, usually indicate granulomatous anterior uveitis
• hypotony- decreased intra-ocular pressure
• diffuse corneal edema

• Ocular: corneal ulceration, lens induced (hypermature cataract), ocular trauma, primary ocular neoplasia
• Systemic: bacteremia, viremia, septicemia, autoimmune, secondary to metastatic neoplasia

rule out ocular causes first (only 4 ocular causes of anterior uveitis)

• melanoma
• adenoma/ adenocarcinoma originating from the ciliary body
• spindle cell sarcoma (cats only)

• lymphosarcoma 
• metastatic carcinoma
• undifferentiated sarcoma (histiocytic sarcoma), hemangiosarcoma, osteosarcoma, etc

idiopathic/ immune-mediated; neoplasia, systemic infectious disease

auto-immue disorder directed against melanin [dogs]; poliosis, vitiligo, uveitis

Ehrlichia canis, Blastomycosis dermatitidis, Crypto, Histoplasmosis, Rocky Mountain Spotted Fever, Dirofilaria immitis, Lyme Disease, Leishmaniasis

idiopathic/ immune- mediated; systemic infectious disease, neoplasia (least)

FeLV, FIP, Toxoplasma, FIV, Cryptosporidium, Bartonella

• directed towards the inciting cause
• requires correct identification of etiologic agent
• antimicrobials, immunotherapies, chemotherapy, etc

• Topical atropine (parasympatholytic): reduce pain by dilating pupil
• topical corticosteroids or NSAIDs (not with an ulcer!): reduce discomfort and inflammatory mediators
• systemic NSAIDS: only with involvement of posterior uvea, if there's an ulcer, or if no response to topical

anterior +/- posterior synechia, cataracts, glaucoma, blindness, phthisis bulbi (shrunken, non-functional eye), lens luxation

• IMMUNE-MEDIATED
• [all postulated, not proven] Leptospira, Onchocerca, viral infection hypersensitivity, Toxoplasmosis, Brucellosis, Streptococcal

• same as uveitis+
• chorioretinitis (butterfly lesions around optic nerve)
• synechia
• atrophy of corpora nigra
• cataract
• chorioretinal scars
• blindness

• Active phase: atropine, prednisolone acetate topical drops, systemic banamine
• Inactive disease: cannot reverse effects

high blood flow; it is predisposed to blood borne diseases and posterior uveitis (bacteremia, septicemia, mycotic infections, disseminated neoplasia)

choroid; the eye is an excellent location to look for vasculitis and bleeding disorders.

• SLE
• uveo-dermatologic syndrome

• thinning of retina (tapetal hyperreflection)
• fundic depigmentation
• hemorrhage
• vasculitis
• edema
• transudate
• exudate (granulomatous, non-granulomatous)
• +/- retinal detachment

• SYSTEMIC MEDICATION
• if infectious, carprofen (SA) or banamine (Eq)
• corticosteroids if etiology does not contraindicate it

blood in the anterior chamber of the eye

• coagulopathy/ vascular disorder
• trauma
• intraocular neoplasia
• hypertension
• sequelae of anterior uveitis
• retinal detachment
• seen with other ocular anomalies (Collie eye)

intra-ocular pressures

treat underlying cause

sharp; blunt

• anterior uveitis
• avoid topical ointments until the fibrous tunic is repaired (will cause granulomatous inflammation in the eye), atropine, antiinflammatories, surgical repair

• intraocular hemorrhage
• uveitis
• lens displacement
• cataracts
• glaucoma
• retinal detachment

• Dogs- usually benign, enucleate only if mass interferes with normal ocular function, young retrievers are predisposed (hereditary)
• Cats- usually metastasizes, all tumors should be enucleated

• may be benign or malignant
• enucleate if mass interferes with normal ocular function

• Fibrous tunic: cornea and sclera
• Vascular tunic: uvea (iris, ciliary body, choroid)
• Nervous tunic: retina

Everything behind the iris: retina and choroid

adhesion of the iris to the cornea (anterior synechia) or to the lens (posterior synechia)