The condition is most frequently observed in children and young adults, especially in regions where ocular surface infections such as staphylococcal blepharitis or tuberculosis are common.

• Age group most affected: 5–30 years.
• Gender: Slight male predominance in some series, but overall distribution is roughly equal.
• Geographic prevalence: Higher in developing countries and in communities with limited access to eye‑care; prevalence estimates range from 0.2 % to 2 % in pediatric ophthalmology clinics in these regions^[1].

Symptoms

Symptoms can vary from mild irritation to severe pain and visual disturbance. Common features include:

• Redness (hyperemia): Diffuse or localized to the limbus.
• Foreign‑body sensation: The feeling that something is in the eye.
• Burning or itching: Often worse in the evening.
• Tearing (epiphora): Excessive watery discharge.
• Photophobia: Light sensitivity that may cause squinting.
• Linear or nodular corneal infiltrates: Visible as small white‑yellow raised lesions.
• Ulceration: If a phlyctenule ruptures, a small ulcer may develop, leading to a gritty feeling.
• Decreased visual acuity: Usually mild, but can progress if scarring occurs.
• Palpebral crusting: Especially if concurrent blepharitis is present.

Causes and Risk Factors

Underlying Mechanism

PKC is a type of delayed‑type (Type IV) hypersensitivity reaction. Antigens from bacteria, fungi, or other microorganisms trigger an immune response that results in localized inflammation at the corneal‑conjunctival junction.

Common Triggers

• Staphylococcus aureus: The most frequent bacterial antigen, especially in cases associated with chronic blepharitis.
• Mycobacterium tuberculosis: Particularly in endemic regions; a positive Mantoux test is frequently found.
• Fungal spores: Aspergillus or Candida species in agricultural settings.
• Parasitic antigens: Rarely, parasites such as Demodex may act as triggers.

Risk Factors

• Age 5‑30 years (immune system still maturing).
• Chronic blepharitis or meibomian gland dysfunction.
• Living in crowded or unsanitary conditions that facilitate ocular surface colonization.
• History of tuberculosis or close contact with an active case.
• Contact lens wear (especially poor hygiene).
• Systemic immune dysregulation (e.g., atopic dermatitis).

Diagnosis

Diagnosis is primarily clinical, based on a characteristic slit‑lamp appearance, but ancillary tests help confirm the underlying cause.

Clinical Examination

• Slit‑lamp biomicroscopy: Reveals small (0.5‑2 mm) white or yellowish nodules at the limbus with surrounding vascular injection. Older lesions may show a central ulcer with an overlying fibrinous membrane.
• Fluorescein staining: Highlights any corneal epithelial defects or ulceration.
• Eyelid inspection: Looks for blepharitis, crusting, or meibomian gland blockage.

Laboratory and Imaging Studies

• Conjunctival swab or impression cytology: To isolate bacterial, fungal, or mycobacterial organisms when infection is suspected.
• Culture and sensitivity: Guides targeted antibiotic therapy.
• Mantoux (tuberculin) test or IGRA: Screen for latent tuberculosis.
• Serologic tests for HIV: Considered in immunocompromised patients.
• Anterior segment optical coherence tomography (AS‑OCT): Provides high‑resolution images of infiltrate depth, useful for monitoring response to therapy.

Treatment Options

The goal is to eliminate the inciting antigen, control inflammation, and prevent scarring.

Medical Management

• Topical corticosteroids: First‑line for active inflammation (e.g., prednisolone acetate 1 %). Typical regimen: 4‑6 times daily for 1 week, then taper based on response. Long‑term use requires intraocular pressure (IOP) monitoring.
• Topical non‑steroidal anti‑inflammatory drugs (NSAIDs): May be used as steroid‑sparing agents (e.g., ketorolac 0.5 %).
• Antibiotic therapy:
  • Empiric broad‑spectrum topical antibiotics (e.g., moxifloxacin 0.5 %) for 5–7 days to cover Staphylococcus.
  • If Staphylococcus is confirmed, a targeted agent such as erythromycin ointment 0.5 % can be continued.
• Antitubercular therapy (ATT): When Mycobacterium tuberculosis is identified or Mantoux test is strongly positive, a standard 6‑month regimen (isoniazid, rifampin, ethambutol, pyrazinamide) is indicated per WHO guidelines^[2].
• Antifungal drops: For confirmed fungal etiology (e.g., natamycin 5 %).

Procedural Interventions

• Debridement of necrotic tissue: Rarely needed but can hasten healing when a large ulcer is present.
• Amniotic membrane transplantation: Considered for persistent epithelial defects or impending perforation.
• Cycloplegic agents (e.g., cyclopentolate 1 %): Reduce painful ciliary spasm and photophobia.

Lifestyle and Supportive Measures

• Warm compresses and lid hygiene (soap‑free lid scrubs twice daily) to control blepharitis.
• Avoidance of contact lenses until the inflammation fully resolves.
• Use of preservative‑free artificial tears 4–6 times daily for comfort.

Living with Keratoconjunctivitis Cornealis (Phlyctenular Keratoconjunctivitis)

Daily Management Tips

• Adhere to medication schedule: Missing doses of steroids or antibiotics can lead to flare‑ups.
• Protect your eyes: Wear sunglasses outdoors to reduce photophobia and UV‑induced aggravation.
• Maintain eyelid hygiene: Use commercially available lid‑scrub pads or diluted baby shampoo.
• Monitor intra‑ocular pressure (IOP): If you are on topical steroids for more than 2 weeks, have your eye doctor check IOP every 2–4 weeks.
• Stay up to date with vaccinations: Especially BCG in TB‑endemic areas, as it may lower systemic sensitization.
• Follow up appointments: Initially weekly, then every 4–6 weeks once stable.

Impact on Vision & Activities

Most patients regain full visual acuity after treatment, but scarring at the limbus can cause mild astigmatism. An optometrist may need to prescribe glasses or contact lenses after the acute phase.

Prevention

• Good ocular surface hygiene: Daily lid cleaning, regular hand washing before touching eyes.
• Prompt treatment of blepharitis or skin infections: Reduces the bacterial antigen load.
• Screen for tuberculosis: In high‑risk settings, a Mantoux test or IGRA should be performed annually.
• Proper contact‑lens care: Use recommended solutions, replace lenses as scheduled, and avoid overnight wear unless approved.
• Environmental control: Reduce exposure to dust, smoke, and agricultural aerosols that may carry fungal spores.

Complications

If PKC is not adequately treated, several complications may arise:

• Corneal scarring: Leads to permanent visual impairment and irregular astigmatism.
• Corneal neovascularization: New blood vessels invade the cornea, further compromising transparency.
• Perforation: Rare but serious; requires surgical intervention.
• Secondary bacterial or fungal infection: Ulcerated lesions become a portal for opportunistic pathogens.
• Glaucoma: Prolonged steroid use can elevate IOP.

When to Seek Emergency Care

Sources:
[1] World Health Organization. “Prevalence of ocular surface disease in children.” WHO Vision Fact Sheet, 2022.
[2] WHO. “Guidelines for the treatment of tuberculosis, 2023 Update.”
[3] Mayo Clinic. “Phlyctenular keratoconjunctivitis.” Updated 2023.
[4] American Academy of Ophthalmology. “Keratoconjunctivitis – Clinical Practice Guidelines.” 2021.
[5] National Eye Institute, NIH. “Eye Health Information: Inflammatory Eye Diseases.” 2022.