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Basics ⬇

Basics

DEFINITION

Pathophysiology

  • Increased permeability of the blood-aqueous barrier related to infectious, immune- mediated, neoplastic, traumatic, or other causes; allows entrance of plasma proteins and blood cellular components into aqueous humor.
  • Disruption of blood-aqueous barrier is initiated and maintained by numerous chemical mediators, including histamine, prostaglandins, leukotrienes, serotonin, kinins, and complement.

Systems Affected

  • Ophthalmic.
  • Other systems may also be affected by underlying disease process.

Incidence/Prevalence

  • Relatively common condition.
  • True incidence/prevalence unknown.

Geographic Distribution

Geographic location may affect incidence of certain infectious causes of uveitis.

Signalment

Species

Cat

Mean Age and Range

  • Mean age 7–9 years.
  • Any age may be affected.

Predominant Sex

Males/neutered males more commonly affected than females.

Signs

Historical Findings

  • Cloudy eye-due to corneal edema, aqueous flare, hypopyon, etc.
  • Painful eye-manifest by blepharospasm, photophobia, or rubbing eye; usually less pronounced than in dogs.
  • Red eye-due to conjunctival hyperemia and ciliary flush; less pronounced than in dogs in most cases.
  • Vision loss-variable.

Physical Examination Findings

Importance of a thorough physical examination in cats presenting with uveitis cannot be overstated.

Ophthalmic Findings

  • Ocular discomfort-manifest by blepharospasm and photophobia
  • Ocular discharge-usually serous; sometimes mucoid to mucopurulent.
  • Conjunctival hyperemia-bulbar and palpebral conjunctiva both usually affected.
  • Corneal edema-diffuse; mild to severe.
  • Keratic precipitates-multifocal aggregates of inflammatory cells adherent to corneal endothelium; most notable ventrally.
  • Aqueous flare and cells-cloudiness of aqueous humor due to increased protein content and suspended cellular debris; best visualized with a bright, narrow beam of light shined through anterior chamber.
  • Ciliary flush-injection of deep perilimbal anterior ciliary vessels.
  • Deep corneal vascularization-circumcorneal distribution (brush border).
  • Miosis and/or resistance to pharmacologic dilation.
  • Iridal swelling-may be generalized or nodular.
  • Reduced IOP is consistent with anterior uveitis but is not a uniform finding.
  • Posterior synechia-adhesions between posterior iris and anterior lens surface.
  • Fibrin in anterior chamber.
  • Hypopyon or hyphema-accumulations of white blood cells or red blood cells, respectively, in the anterior chamber; usually settles horizontally in ventral aspect of chamber but may be diffuse.
  • Chronic changes may include rubeosis iridis, iridal hyperpigmentation, secondary cataract, lens luxation, pupillary seclusion, iris bombé, secondary glaucoma, and phthisis bulbi.

Causes

  • Infectious-mycotic (Blastomyces spp., Cryptococcus neoformans; Coccidiodes immitis; Histoplasma capsulatum); protozoal (Toxoplasma gondii; Leishmania infantum); bacterial (Bartonella spp., Mycobacterium spp. or any bacterial septicemia); viral (FIV, FeLV, feline coronavirus; FHV-1); parasitic (ophthalmomyiasis; ocular larval migrans).
  • Idiopathic-lymphocytic-plasmacytic uveitis.
  • Immune-mediated-reaction to lens proteins (due to cataract or lens trauma).
  • Neoplastic-primary ocular tumors (esp. diffuse iris melanoma, ocular sarcoma); metastasis to uveal tract (esp. lymphoma).
  • Metabolic-hyperlipidemia; hyperviscosity; systemic hypertension.
  • Miscellaneous-trauma (blunt or penetrating); ulcerative keratitis; corneal stromal abscess; toxemia of any cause.

Risk Factors

None specific; immune suppression and geographic location may increase incidence of certain infectious causes of uveitis.

Diagnosis ⬆ ⬇

Diagnosis

Differential Diagnosis

  • Conjunctivitis-redness limited to conjunctival hyperemia (i.e., no ciliary flush); ocular discharge usually thicker and more copious than in uveitis; discomfort may be alleviated by topical anesthetic.
  • Glaucoma-elevated IOP is most consistent distinguishing feature of this disease; others may include dilated pupil, Haab's striae, and buphthalmos.
  • Ulcerative keratitis-corneal fluorescein staining will detect ulcers; corneal edema associated with ulcers is either localized to, or most severe at, site of ulcer; ocular discharge often thicker and more copious than with uveitis; discomfort may be alleviated by topical anesthetic.
  • Horner's syndrome-miosis, enophthalmos, and nictitans protrusion are similar in both conditions, but Horner's is non-painful with no ocular discharge; ptosis with Horner's is distinguished from blepharospasm, as the latter is an active process; minor conjunctival hyperemia may be noted with Horner's, but cornea and anterior chamber are clear; clinical signs of Horner's syndrome resolve following topical application of ophthalmic 1–10% phenylephrine.

CBC/Biochemistry/Urinalysis

  • CBC-often normal; changes may be present related to underlying disease.
  • Biochemistry-often normal; most common abnormality in cats with uveitis is elevated serum proteins (usually due to polyclonal gammopathy).
  • Urinalysis-often normal; changes may be present related to underlying disease.

Other Laboratory Tests

  • FeLV serum titers.
  • FIV serum titers.
  • Coronavirus titers-not specific for FIP but may influence the index of suspicion for this disease.
  • Toxoplasma gondii IgM and IgG titers performed on serum and/or aqueous humor.
  • Bartonella spp. serology, PCR (serum or aqueous humor) and/or blood culture.

Imaging

  • Thoracic radiography-may show evidence of causative disease process (e.g., infiltrates related to infectious disease; evidence of metastatic neoplastic disease).
  • Ocular ultrasound-indicated if opacity of ocular media precludes direct examination; may reveal intraocular neoplasm or retinal detachment.

Diagnostic Procedures

  • Tonometry-low IOP consistent with uveitis; elevated IOP indicates glaucoma (primary disease or secondary to uveitis).
  • Ocular centesis-if retinal detachment is present, cytology of subretinal aspirate may reveal causative agents; anterior chamber centesis may be performed for Toxoplasma gondii or Bartonella IgM and IgG titers on aqueous humor.

Pathologic Findings

  • Gross-see physical examination findings.
  • Histopathologic-corneal edema; peripheral corneal deep stromal vascularization; keratic precipitates; preiridal fibrovascular membrane; peripheral anterior synechia; posterior synechia; entropion or ectropion uveae; leukocyte accumulation in iris, ciliary body, sclera, choroid (lymphocytic-plasmacytic, suppurative, or granulomatous infiltrates, depending on etiology); secondary cataract; with posterior segment involvement in inflammatory process, cyclitic membrane; vitreal traction bands and retinal detachment may be present.
  • Lymphoplasmacytic infiltrate of iris and ciliary body (either diffuse or nodular) is most common histopathologic finding.

Treatment ⬆ ⬇

Treatment

Appropriate Health Care

  • Outpatient medical management generally sufficient.

Activity

No changes indicated in most cases.

Diet

No changes indicated.

Client Education

  • Inform of potential systemic diseases causing ophthalmic signs and emphasize importance of appropriate diagnostic testing.
  • In addition to symptomatic uveitis treatment, treatment of underlying disease (when possible) is paramount to a positive outcome.
  • Inform of potential complications and emphasize compliance with treatment and follow-up recommendations that will reduce the likelihood of complications.

Surgical Considerations

  • None in most cases.
  • Specific instances requiring surgical intervention include removal of ruptured lenses and surgical management of secondary glaucoma.
  • Chronic uveitis leading to secondary glaucoma commonly necessitates enucleation of affected globes.
  • Enucleation is recommended in cats with uveitis related to diffuse iris melanoma or other primary intraocular tumors.

Medications ⬆ ⬇

Medications

Drug(s)

Corticosteroids

Topical

  • Prednisolone acetate 1%-apply 2–8 times daily, depending on severity of disease; taper medication as condition resolves.
  • Dexamethasone 0.1%-apply 2–8 times daily, depending on severity of disease; taper medication as condition resolves.
  • Other topical corticosteroids (e.g., betamethasone, hydrocortisone) are considerably less effective in the treatment of intraocular inflammation.
  • Taper treatment frequency as condition improves; stopping topical corticosteroids abruptly may result in rebound of ocular inflammation.

Subconjunctival

  • Triamcinolone acetonide 4 mg by subconjunctival injection.
  • Methylprednisolone 4 mg by subconjunctival injection.
  • Often not required.
  • Indicated only in severe cases as one-time injection, followed by topical and/or systemic anti-inflammatories.

Systemic

  • Prednisone 1–3 mg/kg/day initially; taper dose after 7–10 days.
  • Use only if systemic infectious causes of uveitis have been ruled out.

Nonsteroidal Anti-inflammatory Drugs

Topical

  • Flurbiprofen-apply 2–4 times daily, depending on severity of disease.
  • Diclofenac-apply 2–4 times daily, depending on severity of disease.

Systemic

  • Meloxicam 0.2 mg/kg IV, SC, PO once, then 0.05 mg/kg IV, SC, PO q24h for 2 days, then 0.025 mg/kg q24–48h. Due to potential renal effects, limit duration of use to 4 days.
  • Robenacoxib 1 mg/kg PO once daily; limit duration of use to 3 days.
  • Ketoprofen 1 mg/kg PO q24h; limit duration of use to 5 days.

Topical Mydriatic/Cycloplegic

  • Atropine sulfate 1%-apply 1–4 times daily, depending on severity of disease. Use lowest frequency adequate to maintain dilated pupil and ocular comfort; taper medication as condition resolves. Ointment is preferred over solution in cats as it causes less salivation.

Contraindications

  • Avoid the use of miotic medications (e.g., pilocarpine), including topical prostaglandins (e.g., latanoprost), in the presence of uveitis.
  • Topical and subconjunctival corticosteroids are absolutely contraindicated in the presence of ulcerative keratitis.
  • Corticosteroids (especially systemic) should be avoided in cats with systemic hypertension. Avoid systemic NSAIDs in cats with renal disease.

Precautions

Owing to concern for secondary glaucoma, topical atropine should be used judiciously and IOP should be monitored periodically.

Possible Interactions

Systemic corticosteroids and nonsteroidal anti-inflammatory drugs should not be used concurrently.

Follow-Up ⬆ ⬇

Follow-Up

Patient Monitoring

Recheck in 3–7 days, depending on severity of disease. IOP should be monitored at recheck to detect secondary glaucoma. Frequency of subsequent rechecks dictated by severity of disease and response to treatment.

Possible Complications

Systemic Complications

Occur as a result of the systemic etiology of the uveitis.

Ophthalmic Complications

  • Secondary glaucoma-common complication of chronic uveitis in cats.
  • Secondary cataract.
  • Lens luxation.
  • Retinal detachment.
  • Phthisis bulbi.

Expected Course and Prognosis

  • Guarded prognosis for affected eyes. Depends on underlying disease and response to treatment.
  • Cats with treatable underlying disease (e.g., toxoplasmosis) are more likely to have a favorable ophthalmic outcome than those with idiopathic lymphocytic- plasmacytic uveitis or untreatable underlying condition (e.g., FIP, FIV).

Miscellaneous ⬆

Miscellaneous

Age-Related Factors

  • Younger cats more likely to be diagnosed with infectious etiology.
  • Older cats at higher risk of idiopathic lymphocytic-plasmacytic uveitis and intraocular neoplastic causes.

ZOONOTIC POTENTIAL

  • None in most cases.
  • Some forms of systemic infection causing uveitis may pose a slight risk to immunocompromised owners.

Pregnancy/Fertility/Breeding

Avoid systemic corticosteroids. Because of systemic absorption, topical corticosteroids may also pose a risk, especially with frequent application.

Synonym

Iridocyclitis

Abbreviations

  • FeLV = feline leukemia virus
  • FHV-1 = feline herpesvirus type 1
  • FIP = feline infectious peritonitis
  • FIV = feline immunodeficiency virus
  • IOP = intraocular pressure

Suggested Reading

Cullen C, Webb A. Ocular manifestations of systemic diseases. Part 2: The cat. In: Gelatt KN, ed., Veterinary Ophthalmology, 5th ed. Ames, IA: Wiley-Blackwell, 2013, pp. 1978–2036.

Martin C. Anterior uvea and anterior chamber. In: Ophthalmic Disease in Veterinary Medicine. London: Manson Publishing, 2010, pp. 298–336.

Miller P. Uvea. In: Maggs DJ, Miller PE, Ofri R, Slatter's Fundamentals of Veterinary Ophthalmology, 5th ed. St. Louis, MO: Elsevier Saunders, 2013, pp. 220–246.

Stiles J. Feline ophthalmology. In: Gelatt KN, ed., Veterinary Ophthalmology, 5th ed. Ames, IA: Wiley-Blackwell, 2013, pp. 1477–1559.

Author Ian P. Herring

Consulting Editor Paul E. Miller

Client Education Handout Available Online