Definition

Inflammation of the conjunctiva, the vascularized mucous membrane that covers the anterior portion of the sclera (bulbar conjunctiva) and lines the eyelids (palpebral conjunctiva) and third eyelid.

Pathophysiology

• Primary-allergic; infectious; environmental.
• Secondary to other ocular disease-KCS, entropion, distichiasis.

Systems Affected

Ophthalmic-ocular with possible eyelid involvement.

Genetics

N/A

Incidence/Prevalence

Common

Geographic Distribution

N/A

Signalment

Signs

• Blepharospasm
• Conjunctival hyperemia
• Ocular discharge-serous, mucoid, or mucopurulent
• Chemosis
• Follicle formation on posterior third eyelid surface
• Enophthalmos and third eyelid elevation

Causes

Risk Factors

Atopy and KCS

Differential Diagnosis

• Must distinguish primary conjunctivitis from secondary conjunctival hyperemia or referred inflammation.
• Thorough systematic ophthalmic exam allows rule out of other potential diseases (e.g., KCS, ulcers, uveitis, glaucoma, orbital disease); assess pupil size and symmetry, look for aqueous flare, attempt globe retropulsion, perform Schirmer tear test, IOP and fluorescein staining.
• Deeper, darker, more linear and immobile blood vessel injection indicates episcleral vasculature congested due to episcleritis or intraocular disease.
• Mass biopsy will differentiate conjunctival neoplasia (rare: melanoma, hemangioma, hemangiosarcoma, lymphoma, papilloma, mast cell tumor) or nodular episcleritis.

CBC/Biochemistry/Urinalysis

Normal, except with systemic disease.

Other Laboratory Tests

N/A

Imaging

N/A

Diagnostic Procedures

• Thorough adnexal examination-rule out facial nerve paralysis, lagophthalmos, eyelid abnormalities, hair or eyelash disorders, and foreign bodies in cul-de-sacs or under third eyelid.
• Schirmer tear test-measures aqueous tears to diagnose or rule out KCS; perform before anything else is placed in the eye.
• Fluorescein stain-no corneal retention rules out ulcerative keratitis; stain flow to nares rules out nasolacrimal disease.
• Tear film breakup time-assesses tear film stability to rule out qualitative tear deficiency.
• Intraocular pressures-rule out glaucoma.
• Globe retropulsion-rule out orbital disease.
• Examine for signs of anterior uveitis (e.g., hypotony, aqueous flare, and miosis) or other intraocular disease (e.g., cataracts, lens luxation).
• Consider a nasolacrimal duct flush-rule out nasolacrimal disease if fluorescein stain did not pass to nares.
• Aerobic bacterial culture and sensitivity-consider with mucopurulent discharge if KCS has been ruled out; ideally, specimens are taken before anything is placed in the eye (e.g., topical anesthetic, fluorescein, and flush) to prevent inhibition or dilution of bacterial growth.
• Conjunctival cytology-may reveal a cause (rare); lymphocytes and plasma cells diagnostic for lymphocytic/plasmacytic conjunctivitis; eosinophils may help diagnose allergic conjunctivitis; may see degenerate neutrophils and intracytoplasmic bacteria indicating bacterial infection; rarely see distemper virus intracytoplasmic inclusion bodies.
• Conjunctival biopsy-may be useful with mass lesions and nodular episcleritis or chronic disease for which a definitive diagnosis has not been made.
• Intradermal skin testing-may be helpful with suspected allergic conjunctivitis.

Pathologic Findings

• Biopsy-typical signs of inflammation (e.g., neutrophils and lymphocytes); may note infectious agents.
• Histopathology of mass lesions may reveal neoplasia or nodular episcleritis.
• Ligneous conjunctivitis-thick amorphous eosinophilic hyaline-like material.

Appropriate Health Care

• Primary-often outpatient.
• Secondary to other diseases (e.g., ulcerative keratitis, uveitis, glaucoma, lens luxation)-may require hospitalization to address a severe underlying ophthalmic issue.

Nursing Care

• Irritant induced conjunctivitis-flush ocular surfaces and remove foreign body if observed.
• Allergic or follicular conjunctivitis-instruct the client to apply a viscous artificial tear gel to both eyes before the patient is active outdoors (q8–12h) then flush the ocular surface with eye wash when returning indoors to remove “trapped” allergens.
• Secondary to ectropion or medial canthal pocket syndrome-instruct the client to flush the ocular surface with eye wash daily to remove dust, dirt, or other particulate matter that collects ventrally.

Activity

• No restriction for most patients.
• Suspected contact irritant or acute allergic disease-prevent contact with the offending agent.
• Do not expose patients with infectious viral disease to susceptible animals.

Diet

• No change for most patients.
• Suspected underlying skin disease and/or food allergy-food elimination diet recommended.

Client Education

• When solutions and ointments are prescribed, instruct the client to use the solution(s) before the ointment(s) and wait at least 5 minutes between treatments.
• If copious discharge is noted, instruct the client to clean the eyes before giving medication.
• Instruct the client to call for instructions if the condition fails to improve or worsens, which indicates that the condition may not be responsive, may be progressing, or that the animal may be having an adverse reaction to a prescribed medication.
• Inform the client that an Elizabethan collar should be placed on the patient if self-trauma occurs.

Surgical Considerations

• Follicular conjunctivitis-if follicles are large and unresponsive to medical care, consider follicle debridement.
• Entropion, distichia, or other eyelid disease-perform temporary or permanent surgery depending on the findings, signalment and history.
• Nasolacrimal duct obstruction-if repeated flushing attempts at weekly intervals along with medical therapy is unsuccessful consider contrast study and surgery (see Epiphora).
• Conjunctival neoplasia-depending on tumor type and extent of involvement may involve local excision and adjunctive therapy (-irradiation, cryotherapy), enucleation, or exenteration.

Drug(s) Of Choice

Contraindications

Topical corticosteroids-avoid if corneal ulceration is present, patient is at high risk for ulceration (e.g., entropion, lagophthalmos, severe KCS), and with known or suspected infectious conjunctivitis.

Precautions

• Topical medications may be irritating.
• Topical corticosteroids-monitor all patients carefully for signs of corneal ulceration; discontinue agent immediately if corneal ulceration occurs.

Possible Interactions

N/A

Alternative Drug(s)

Other corticosteroids-1% prednisolone acetate; betamethasone; hydrocortisone.

Patient Monitoring

Recheck shortly after beginning treatment (at 5 days); then recheck in 2 weeks or as needed.

Prevention/Avoidance

Treat any underlying disease that may be exacerbating the conjunctivitis (e.g., KCS, allergic or immune-mediated skin disease).

Possible Complications

N/A

Expected Course and Prognosis

• Good prognosis when underlying cause identified and treated (e.g., KCS, adnexal disease, eyelash disorder).
• Bacterial-usually resolves with appropriate antibiotics; may depend on resolution of underlying disease (e.g., KCS).
• Allergic or follicular-nursing care or medical treatment may be needed during peak allergy times.
• Lymphocytic/plasmacytic-tend to be controlled and not cured; may require chronic treatment at the lowest level possible.

Associated Conditions

• Atopy
• Pyoderma

Age-Related Factors

N/A

Zoonotic Potential

N/A

Pregnancy/Fertility/Breeding

Use topical and systemic medications with caution, if at all, in pregnant animals.

See Also

• Epiphora
• Keratoconjunctivitis Sicca
• Red Eye

Abbreviation

KCS = keratoconjunctivitis sicca

Client Education Handout Available Online