Endophthalmitis/Panophthalmitis in Cats (Felis) | Vetlexicon
felis - Articles

Endophthalmitis/Panophthalmitis

ISSN 2398-2950

Contributor(s) :


Introduction

  • Endophthalmitis is inflammation of the internal structures of the eye, namely the uvea, retina, vitreous, and sometimes the lens.
  • Panophthalmitis is purulent inflammation of all parts of the eye, and often arises when endophthalmitis extends into the cornea and sclera.
  • Cause: bacteria, mycoses, foreign bodies Eye: ocular foreign body  Cornea: foreign body , neoplasia, feline infectious peritonitis (rare) Feline infectious peritonitis.
  • Signs: panuveitis, blindness, secondary glaucoma Glaucoma, possible distortion of the shape or size of the eye.
  • Diagnosis: clinical examination, bacterial culture, histopathology.
  • Treatment: topical and systemic antibiotic or antifungal agents.
  • Prognosis:
    • Endophthalmitis: poor for saving vision, fair for saving the globe.
    • Panophthalmitis: guarded, usually requires enucleation

Presenting signs

  • Obviously inflamed eye.
  • Blindness Blindness.
  • Possible change in the shape or size of the eye.
  • Sometimes systemic signs:
    • Fever.
    • Weight loss
    • Lethargy, etc.
  • Pain.

Acute presentation

  • Grossly inflamed eye, with cloudiness, redness, pain, tearing, etc.
  • Possible enlargement of the eye.

Geographic incidence

  • The systemic mycotic infections have regional geographic distributions within the United States.

Age predisposition

  • Histoplasmosis Histoplasmosis: young cats (< 4 years).
  • Penetrating foreign bodies: young cats.

Breed/Species predisposition

  • Outdoor cats of all breeds.

Public health considerations

  • None.

Cost considerations

  • Inexpensive to moderately expensive to diagnose.
  • Expensive to treat.

Pathogenesis

Etiology

  • Endophthalmitis/panophthalmitis falls into roughly three etiologic categories:
  • Inflammation associated with an underlying systemic illness, ie. the systemic mycoses, neoplasia, bacterial septicemia (rare), and feline infectious peritonitis (rare; primarily endophthalmitis). Any infectious cause of chorioretinitis can potentially result in endophthalmitis, but the diseases listed are the most common causes.
  • Inflammation associated with a bacterial infection that is introduced into the eye, eg following surgery to remove the lens, following penetrating ulcers, or associated with contamination of penetrating wounds (especially cat scratches).
  • Inflammation associated with migration of penetrating foreign bodies. This last category may or may not be complicated by bacterial infection.

Predisposing factors

General

  • Exposure to pathogenic or drug resistant bacteria.
  • Pre-existing inflammation within the eye or penetration of the eye.

Pathophysiology

  • Endophthalmitis may begin as penetrating keratitis Keratitis, anterior uveitis Anterior uvea: traumatic uveitis or chorioretinitis Eye: chorioretinitis. Progressive infection and necrosis, or migration/inflammation induced by a foreign body results in extension of the inflammation into the surrounding or adjacent structures.
  • Panophthalmitis results when the sclera also becomes involved. Panophthalmitis may then extend into the periocular tissues and affect the episclera, conjunctiva, extraocular muscles, periorbital fat, third eyelid and external eyelids.
  • Endophthalmitis does not usually result in a change in the shape of the eye, although the development of severe secondary glaucoma may cause buphthalmos.
  • Panophthalmitis may cause dramatic thickening of the sclera and periocular tissues, along with secondary glaucoma, and may cause a change in the shape of the eye.
  • Vision is threatened with both conditions, and blindness is almost always present in eyes with panophthalmitis.
  • Extension of inflammation into the optic nerve may also occur.

Timecourse

  • Most cases of endophthalmitis/panophthalmitis develop rapidly. Clinical signs may develop within 24-72 hours.
  • The clinical course is often protracted, with therapy required for several weeks to months.

Diagnosis

Presenting problems

  • Grossly inflamed eye, with cloudiness, redness, pain, tearing, etc.
  • Possible enlargement of the eye.
  • Blindness in the affected eye.
  • Animal may be systemically ill.

Client history

  • Eye is red, cloudy and painful.
  • Eye may have an abnormal shape.
  • Animal may be feeling ill.
  • History may be revealing if intraocular surgery, a cat fight, or removal of a foreign body occurred recently.

Clinical signs

  • Tearing or purulent discharge.
  • Blepharospasm.
  • Corneal cloudiness.
  • Conjunctival and episcleral hyperemia.
  • Possible swelling of the globe, episcleral tissue, periocular tissues and eyelids.
  • Possible chemosis.
  • Possible protrusion of the third eyelid.
  • Blindness.

Diagnostic investigation

Ophthalmic examination

  • Endophthalmitis is suspected when more than one intraocular structure is inflamed, or when the globe has been penetrated. Corneal edema, hypopyon, marked aqueous flare, cataract formation, miosis, thickening of the iris, rubeosis iridis, and chorioretinitis are common findings.
  • Panophthalmitis is suspected when intraocular inflammation is accompanied by scleritis and periocular inflammation. In addition to the clinical findings of endophthalmitis, exudative retinal detachment and complete opacification of the posterior segment may also be found.
  • Secondary glaucoma is a common sequela.

Physical examination

  • When there is no history of prior corneal ulceration, a recent cat fight, exposure to foreign bodies or intraocular surgery, then a complete physical examination is indicated.

Laboratory tests and radiography

  • For suspected systemic illnesses, a CBC, biochemistry profile, UA, chest and abdominal x-rays and serologic testing for systemic mycoses and FIP/FCV are performed.
  • Cytologic examination of fine needle aspirates and biopsy specimens may also reveal infectious agents.
  • For eyes with endophthalmitis, aqueous humor may be aspirated and submitted for bacterial culture.
  • For blind eyes with panophthalmitis, aspirate of material from the vitreous may reveal mycotic agents, and may be submitted for bacterial culture.

Ultrasonography and advanced imaging

  • Ocular ultrasonography is helpful when the eye is too opaque to allow a thorough examination of either the anterior or posterior segment.
  • Ultrasonography can be disappointing, however, when searching for foreign bodies. Metallic foreign bodies and occasionally, porcupine quills, may be found on ocular ultrasonography.
  • Magnetic resonance imaging is the best technique for identifying ocular foreign bodies, but is contraindicated in the presence of ferrous metal foreign bodies.
  • Abdominal ultrasonography may be indicated with certain suspected systemic infections and neoplasia.

Histopathology

  • Although endophthalmitis may be suspected based upon the clinical examination, it often requires histopathologic confirmation.
  • Histopathologic examination of enucleated eyes usually confirms the underlying cause and the extent of the inflammation.

Confirmation of diagnosis

Discriminatory diagnostic features

  • Ophthalmic examination findings of diffuse or severe inflammation involving multiple intraocular and periocular structures.
  • Positive serologic testing.
  • Positive cytologic evidence of systemic mycoses or neoplasia elsewhere in the body.

Definitive diagnostic features

  • Positive bacterial culture from the eye.
  • Positive identification of infectious organisms in vitreal aspirates.
  • Histopathologic examination of the eye.

Gross autopsy findings

  • The sclera and periocular tissues may be thickened.
  • Penetrating wounds are rarely obvious.
  • The vitreous cavity may be filled with opaque material.
  • Gross detachment of retina may be noted.

Histopathology findings

  • Endophthalmitis is characterized by inflammatory changes in the anterior and posterior uvea, cataract formation, proteinaceous material in the anterior chamber, and inflammatory cells in the vitreous. The cellular features of the inflammation are highly dependent upon the underlying cause.
  • Panophthalmitis is characterized by dramatic inflammation of the sclera, often with extension into the surrounding tissues. Retinal detachment is common. Granulomatous changes and necrosis are common findings.

Differential diagnosis

Treatment

Initial symptomatic treatment

  • Bacterial endophthalmitis may benefit from empirical therapy with topical antibiotics Therapeutics: antimicrobial drug.
  • If there is no evidence of corneal ulceration, penetration of the globe, or a recent incision in the eye, topical corticosteroids may also be instituted while a thorough diagnostic work-up is underway.
  • If glaucoma is present, topical beta-blockers or a combination of a topical beta-blocker/carbonic anhydrase inhibitor may be administered.
  • If glaucoma is not present, then mydriasis is induced with topical atropine.
  • Oral (eg ketoprofen Ketoprofen, aspirin) nonsteroidal anti-inflammatory agents may improve the animal's comfort while diagnostic tests are pending.

Standard treatment

  • Treatment is primarily directed against the underlying cause or disease.
  • Bacterial endophthalmitis is treated with topical, subconjunctival and systemic antibiotics. The choice of antibiotics is best decided from culture and antibiotic sensitivity testing.
  • Endophthalmitis associated with the systemic mycoses is treated with itraconazole.
  • Endophthalmitis associated with feline infectious peritonitis virus is poorly responsive to therapy, but topical, subconjunctival, and systemic corticosteroids may be tried.
  • Panophthalmitis is not usually responsive to medical therapy and often requires enucleation of the globe. Postoperatively, systemic antibiotic or antifungal agents may be indicated, depending upon the underlying cause.
  • Chemotherapy may be indicated in the presence of certain systemic neoplasms.
  • When panophthalmitis results from metastasis of a neoplasm, euthanasia should be considered.

Monitoring

  • Improvement in endophthalmitis may be recognized on sequential eye examinations. Evidence of improvement includes clearing of the cornea, a decrease in aqueous flare and hypopyon, a positive response to mydriatics, improved clarity of the vitreous, improvement in any chorioretinitis lesions, and resolution of glaucoma.

Subsequent management

Treatment

  • If endophthalmitis cannot be controlled, if the eye is blind, and if glaucoma results in persistent pain, then enucleation is indicated.

Monitoring

  • Diligent long-term monitoring is necessary when treating eyes afflicted with the systemic mycotic agents. Itraconazole Itraconazole does not penetrate the eye well, and the eye may serve as a persistent nidus of infection.

Prevention

Control

  • Meticulous aseptic technique at the time of lensectomy and other forms of intraocular surgery usually prevents the development of post-operative bacterial endophthalmitis.

Prophylaxis

  • Eyes with severe ulcerative keratitis or penetrating injuries should be started immediately on topical and systemic antibiotics. Subconjunctival antibiotics may also be administered.

Outcomes

Expected response to treatment

  • Bacterial endophthalmitis is the most treatable form of endophthalmitis, but the prognosis for retention of vision is often poor.
  • Mycotic endophthalmitis may respond to therapy, but chorioretinal scarring and optic nerve atrophy from glaucoma may result in blindness.
  • Many cases of mycotic and FIP endophthalmitis, and most cases of endophthalmitis/panophthalmitis caused by neoplasia, and migrating foreign bodies are not responsive to medical therapy and require enucleation Eye: enucleation.

Reasons for treatment failure

  • Inflammation is too severe to overcome.
  • The underlying infectious agent is resistant to therapy.
  • The medical therapy does not penetrate the eye well.
  • Therapy is not administered for an adequate duration.
  • The diagnosis is incorrect.

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Whitley R D (2000) Canine and feline primary ocular bacterial infections. Vet Clin North Am Samll Anim Pract 30 (5),  1151-1167 PubMed.
  • Taylor M M, Kern T J, Riis R C et al (1995) Intraocular bacterial contamination during cataract surgery in dogs. J Am Vet Med Assoc 206 (11), 1716-1720 PubMed.

Other sources of information

  • Wilcock B (2001) General pathology of the eye. In: Slatter D Fundamentals of Veterinary Ophthalmology. 3rd Ed. WB Saunders, Philadelphia, pp 68-84.
  • Petersen-Jones S & Crispin S (2002) BSAVA Manual of Small Animal Ophthalmology. 2nd edn. British Small Animal Veterinary Association. ISBN 0 905214 54 4