Case Study

A 55-year-old man presented with an acute onset of redness, severe pain, and decreased vision in his left eye for two days. He had undergone cataract surgery one week earlier.

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Hypopyon

On slit-lamp examination, his visual acuity was counting fingers at 1 meter, with intense conjunctival injection, corneal edema, and a dense layer of white fluid occupying one-third of the anterior chamber inferiorly — a classic hypopyon.

The pupil was poorly reactive, and the view of the posterior segment was obscured. B-scan ultrasonography revealed dense vitreous echoes suggestive of endophthalmitis.

A diagnosis of postoperative infectious endophthalmitis with hypopyon formation was made. The patient was treated urgently with intravitreal antibiotics (vancomycin and ceftazidime) and intensive topical therapy.

Over the next several days, the hypopyon gradually resolved, and pain subsided, but visual recovery remained limited due to retinal involvement.

Disease Overview

Hypopyon refers to the accumulation of white blood cells (pus) in the anterior chamber of the eye, forming a visible fluid level when the patient is upright.

It is a sign of severe intraocular inflammation, usually secondary to infection (such as bacterial or fungal endophthalmitis) or intense sterile inflammation (as in Behçet’s disease or HLA-B27-associated uveitis).

Hypopyon is not a disease by itself but rather a clinical sign indicating a serious underlying ocular or systemic condition that requires prompt diagnosis and management.

Pathophysiology

Hypopyon develops when inflammatory cells (mainly neutrophils) migrate from the limbal vasculature into the anterior chamber in response to infection or inflammation.

These cells, along with fibrin and exudates, accumulate at the bottom of the anterior chamber due to gravity. The process is mediated by cytokines, chemokines, and increased vascular permeability in the iris and ciliary body.

In infectious causes, bacterial toxins or fungal elements directly stimulate this intense immune response. In non-infectious causes (e.g., autoimmune uveitis), immune complexes or autoantigens trigger the inflammatory cascade without microbial invasion.

The hypopyon may be sterile (non-infectious) or purulent (infectious) depending on the etiology.

Hypopyon

Etiology

The causes of hypopyon can be divided broadly into infectious and non-infectious origins:

  1. Infectious Causes:

    • Postoperative Endophthalmitis: The most common cause, usually following cataract or intraocular surgery.

    • Post-traumatic Endophthalmitis: Following penetrating injuries with contamination.

    • Corneal Ulcers (Bacterial, Fungal, or Acanthamoeba): Severe keratitis can lead to spillover inflammation in the anterior chamber.

    • Endogenous Endophthalmitis: Secondary to systemic sepsis, such as from Staphylococcus aureus or Candida albicans infections.

  2. Non-Infectious Causes:

    • HLA-B27-associated Acute Anterior Uveitis

    • Behçet’s Disease

    • Vogt-Koyanagi-Harada Syndrome

    • Sympathetic Ophthalmia

    • Rheumatoid Arthritis-associated Sclerouveitis

    • Leukemic Infiltration or Masquerade Syndromes

Clinical Features

Patients with hypopyon typically present with:

  • Severe ocular pain, photophobia, and redness

  • Blurring of vision or decreased visual acuity

  • White or yellow layer in the lower anterior chamber is visible even without magnification

  • Conjunctival and ciliary injection

  • Corneal edema (especially in infectious cases)

  • In sterile hypopyon, the fluid is usually immobile and may shift minimally with head movements

  • In infectious hypopyon, the material may appear turbid, mobile, and accompanied by fibrin strands

A distinguishing feature of sterile hypopyon (e.g., in Behçet’s disease) is that it is often non-adherent to the corneal endothelium and tends to move freely, whereas in infectious causes (e.g., bacterial keratitis or endophthalmitis), the hypopyon is sticky and immobile due to fibrin deposition.

Diagnostic Evaluation

A comprehensive workup is crucial to determine the underlying cause:

  1. Slit-Lamp Examination: Confirms the presence and extent of hypopyon, corneal ulceration, or keratic precipitates.

  2. Fundus Examination: If possible, to assess posterior segment involvement; if obscured, perform B-scan ultrasonography.

  3. Anterior Chamber Tap or Vitreous Tap: For microbiological culture and sensitivity testing in suspected endophthalmitis.

  4. Corneal Scrapings: In ulcer-related hypopyon, smears and cultures identify causative pathogens.

  5. Blood Tests: ESR, CRP, HLA-B27 typing, autoimmune markers, and infectious serologies (if systemic disease is suspected).

  6. Imaging: Optical Coherence Tomography (OCT) may reveal anterior chamber reaction and retinal involvement in non-infectious cases.

Differential Diagnosis

  • Pseudohypopyon (from tumor cells, hemorrhage, or lipid material)

  • Hyphema (blood in the anterior chamber)

  • Endogenous endophthalmitis

  • Sterile postoperative inflammation

  • Inflammatory uveitis without layering

Hypopyon

Management

The treatment of hypopyon depends entirely on the underlying etiology:

  1. Infectious Hypopyon (Endophthalmitis or Corneal Ulcer):

    • Immediate broad-spectrum intravitreal antibiotics: Vancomycin (1 mg/0.1 ml) + Ceftazidime (2.25 mg/0.1 ml).

    • Intensive topical antibiotics: Fortified tobramycin or cefazolin for corneal ulcers.

    • Systemic antibiotics or antifungals: Based on culture results.

    • Surgical intervention: Pars plana vitrectomy in severe or non-resolving cases.

  2. Non-Infectious Hypopyon (Uveitis):

    • Topical corticosteroids: Prednisolone acetate 1% drops, tapered gradually.

    • Cycloplegic agents: Atropine or cyclopentolate to relieve pain and prevent synechiae.

    • Systemic corticosteroids or immunosuppressive agents: In Behçet’s disease or autoimmune uveitis.

    • Biologic therapies: Anti-TNF agents (e.g., infliximab) in refractory cases of Behçet’s or HLA-B27 uveitis.

Prognosis

The prognosis of hypopyon depends on the speed of diagnosis and the underlying cause.

  • Infectious hypopyon has a guarded prognosis; delayed treatment often results in irreversible vision loss due to retinal damage or scarring.

  • Sterile hypopyon usually resolves completely with corticosteroid therapy, but recurrence is common if the underlying systemic disease remains uncontrolled.

Early intervention, appropriate antimicrobial or anti-inflammatory therapy, and careful follow-up are key to preserving vision and preventing complications such as secondary glaucoma or corneal decompensation.

Prevention

  • Use protective eyewear during high-risk activities to prevent ocular trauma.

  • Maintain sterile surgical techniques to minimize postoperative infections.

  • Monitor systemic inflammatory diseases closely to prevent recurrent uveitis episodes.

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References

  1. Taban M, Behrens A, Newcomb RL, Nobe MY, Saedi G, Sweet PM, McDonnell PJ. Acute endophthalmitis: incidence, presentation, management, and visual outcome. Ophthalmology. 2005;112(7):1180–1186.

  2. Nussenblatt RB, Whitcup SM. Uveitis: Fundamentals and Clinical Practice. 5th ed. Elsevier; 2021.

  3. Okada AA, Johnson MW, Liles WC. Endophthalmitis: update on causative organisms, diagnosis, and management. Curr Opin Ophthalmol. 2020;31(3):207–213.

  4. Sakai J, Fukushima A. Immune mechanisms of hypopyon formation in autoimmune uveitis. Front Immunol. 2022;13:868345.

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