Hypopyon

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Hypopyon

 

Hypopyon—accumulation of white blood cells in the anterior chamber of the eye. Inflammatory breakdown of blood-aqueous barrier allows entry of blood cells into the anterior chamber; chemoattractant mediate influx. Cells often settle in the ventral anterior chamber because of gravity.

Lipid flare—resembles hypopyon but turbidity of the anterior chamber is caused by a high concentration of lipids in aqueous humor. Requires breakdown of the blood-aqueous barrier and concurrent hyperlipidemia to occur.

 

SIGNALMENT

Affects both dogs and cats; no age or sex predilection.

 

SIGNS

Hypopyon—white to yellow opacity within anterior chamber; may be a ventral accumulation of cells or may completely fill the anterior chamber. Fibrin accumulation in anterior chamber may prevent discrete settling of white blood cells, resulting in cells suspended within fibrin matrix. Concurrent ophthalmic signs include blepharospasm, epiphora, diffuse corneal edema, aqueous flare, miosis, iridal swelling, and vision loss.

Lipid flare—diffuse milky appearance to anterior chamber. Concurrent ophthalmic signs may include vision loss, mild blepharospasm, and mild to moderate diffuse corneal edema.

 

CAUSES & RISK FACTORS

Hypopyon

Any cause of uveitis can result in hypopyon. Most commonly, hypopyon is associated with severe uveitis. Hypopyon can also result from neoplastic cell accumulation in ocular lymphoma.

 

Lipid Flare

Lipid flare results from hyperlipidemia and concurrent uveitis. Hyperlipidemia may also destabilize the blood-aqueous barrier directly. Post-prandial lipemia may occasionally result in lipemic aqueous if uveitis is present.

 

DIAGNOSIS

DIFFERENTIAL DIAGNOSIS

Hypopyon

Fibrin in anterior chamber—generally forms an irregular clot, not a ventrally located horizontal line.

 

Lipid Flare

Severe aqueous flare—does not appear as milky/white as lipid flare. Animals with severe aqueous flare generally exhibit much more ocular pain than animals with lipid flare.

Diffuse corneal edema—severe corneal edema may be confused with anterior chamber opacity, but corneal stromal thickening, keratoconus, and corneal bullae are noted with the former.

 

CBC/BIOCHEMISTRY/URINALYSIS

Hypopyon

Often normal; abnormalities related to underlying cause of uveitis may be present.

 

Lipid Flare

Elevated serum triglycerides and cholesterol; other abnormalities may be present related to underlying metabolic disorder(s).

 

OTHER LABORATORY TESTS

Hypopyon

None if hypopyon is related to obvious corneal disease; if related to uveitis, look for underlying cause of uveitis (see Anterior Uveitis—Dogs; Anterior Uveitis—Cats).

 

DIAGNOSTIC PROCEDURES

Anterior chamber centesis indicated with suspicion of neoplastic hypopyon (e.g., lymphoma); unrewarding under other circumstances.

 

TREATMENT

Hypopyon requires aggressive treatment for uveitis and underlying cause. Outpatient treatment is adequate.

Lipid flare requires treatment for uveitis and underlying metabolic disorder. Outpatient treatment is adequate.

 

MEDICATIONS

DRUG(S)

Hypopyon

Corticosteroids

 

Topical

  • Prednisolone acetate 1%—apply 2–6 times daily, depending on severity of disease.
  • Dexamethasone 0.1%—apply 2–6 times daily, depending on severity of disease.
  • Taper medication frequency as condition resolves.

 

Subconjunctival

  • Triamcinolone acetonide 4–6 mg (dog); 4 mg (cat) by subconjunctival injection.
  • Methylprednisolone 3–10 mg (dog); 4 mg (cat) by subconjunctival injection.
  • Indicated as one-time injection followed by topical and/or systemic anti-inflammatories.

 

Systemic

  • Prednisone 0.5–2.2 mg/kg/day (dog); 1–3 mg/kg/day (cat); taper dose after 7–10 days.
  • Only use 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.
  • Much less effective than corticosteroids.

 

Systemic

  • Carprofen 2.2 mg/kg PO q12h or 4.4 mg/kg PO QD (dog).
  • Meloxicam 0.2 mg/kg PO QD (dog).
  • Robenacoxib 1 mg/kg PO q24h; limit duration of use to 3 days (cat).
  • 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; limit duration of use to 4 days (cat).
  • Do not use concurrently with systemic corticosteroids.

Topical Mydriatic/Cycloplegic

  • Atropine sulfate 1%—apply 1–4 times daily, depending on severity of disease. Use ointment instead of solution in cats to minimize salivation.

 

Lipid Flare

  • Topical Corticosteroids
  • Prednisolone acetate 1%—apply 2–4 times daily, depending on severity of disease.
  • Dexamethasone 0.1%—apply 2–4 times daily, depending on severity of disease.
  • Taper medication as condition resolves.
  • Topical Mydriatic/Cycloplegic
  • Atropine sulfate 1%—apply 1–2 times daily, if necessary for perceived ocular discomfort.

 

CONTRAINDICATIONS/POSSIBLE INTERACTIONS

  • Avoid the use of topical miotic medications.
  • Topical and subconjunctival corticosteroids contraindicated if ulcerative keratitis is present.
  • Out of concern for secondary glaucoma, topical atropine should be used judiciously and IOP should be monitored.

 

FOLLOW-UP

PATIENT MONITORING

Recheck in 2–3 days. Intraocular pressure should be monitored to detect secondary glaucoma. Frequency of subsequent rechecks dictated by response to treatment.

 

EXPECTED COURSE AND PROGNOSIS

Hypopyon—prognosis guarded to good; depends on underlying disease and response to treatment.

Lipid flare—prognosis good; generally, responds quickly (within 24–72 hours) to moderate anti-inflammatory therapy; recurrence possible.

 

Visit your veterinarian as early recognition, diagnosis, and treatment are essential.

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