Keratitis

 

👁️‍🗨️ Keratitis

🔍 Definition

Keratitis is inflammation of the cornea, often accompanied by pain, redness, blurred vision, photophobia, and sometimes corneal ulceration. It may be infectious or non-infectious.

🧠 The cornea is avascular and highly innervated, so keratitis can be painful and visually significant.

 

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🌱 Classification

🔹 1. Infectious Keratitis

Caused by bacteria, viruses, fungi, or parasites.

Type	Common Causes
Bacterial	Staph aureus, Pseudomonas, Strep
Viral	Herpes simplex (HSV), Varicella zoster (VZV)
Fungal	Fusarium, Aspergillus, Candida
Parasitic	Acanthamoeba (esp. contact lens wearers)

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🔹 2. Non-Infectious Keratitis

Due to trauma, dry eye, UV exposure, or autoimmune conditions.

Type	Cause
Exposure keratitis	Incomplete eyelid closure (e.g. Bell's palsy)
Neurotrophic keratitis	Reduced corneal sensation (e.g. HSV, diabetes)
Photokeratitis	UV damage (e.g. welding arc, snow blindness)
Dry eye keratitis	Tear film instability
Autoimmune	RA, SLE, Sjogren's, Mooren’s ulcer

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🔬 Clinical Features

Symptom	Notes
Eye pain	Often sharp or aching
Redness	Especially around the limbus (ciliary flush)
Photophobia	Light sensitivity
Blurred vision	Due to corneal clouding or ulceration
Tearing or discharge	May be watery, mucopurulent, or thick
Foreign body sensation	Common in epithelial involvement

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🧪 Signs on Examination

• Corneal ulcer or opacity

• Infiltrate in stroma (white/gray spot)

• Fluorescein staining – shows epithelial defect

• Hypopyon (pus in anterior chamber in severe cases)

• Limbal injection (ciliary congestion)

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🦠 Details on Infectious Types

🧫 Bacterial Keratitis

• Contact lens overuse is a major risk factor

• Pseudomonas is aggressive → rapid ulceration

• Requires urgent topical antibiotics (e.g., fluoroquinolones)

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🧬 Viral Keratitis

• Herpes Simplex Keratitis

  • Dendritic ulcers on fluorescein staining

  • Reduced corneal sensation

  • Treated with topical antivirals (e.g., acyclovir)

• Herpes Zoster Ophthalmicus

  • Involves V1 dermatome of CN V

  • May show pseudodendrites

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🌾 Fungal Keratitis

• History of vegetative trauma (e.g., palm leaf injury)

• Feathery-edged ulcers with satellite lesions

• Treated with antifungals (e.g., natamycin, voriconazole)

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💧 Acanthamoeba Keratitis

• Severe pain disproportionate to signs

• Ring-shaped stromal infiltrates

• Often misdiagnosed; needs anti-amoebic therapy

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🧪 Diagnosis

Test	Purpose
Slit-lamp exam	Visualize ulcer, infiltrate, hypopyon
Fluorescein staining	Epithelial defect and ulcer margins
Corneal scraping	For Gram stain, KOH prep, and culture
Confocal microscopy	Can detect Acanthamoeba
PCR	For viral DNA (in atypical cases)

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💊 Treatment Overview

🔹 General Principles

• Start empirical treatment immediately after corneal scraping

• Adjust therapy based on culture results

🔹 Bacterial

• Topical broad-spectrum antibiotics (e.g., moxifloxacin, fortified ceftazidime + vancomycin)

• Cycloplegics to relieve ciliary spasm

• NO steroids initially (can worsen infection)

🔹 Viral

• Acyclovir ointment or oral acyclovir (for HSV)

• Avoid steroids in active epithelial disease

• For stromal involvement, steroids may be used with antiviral cover

🔹 Fungal

• Natamycin 5%, voriconazole, or amphotericin B

• Longer duration of treatment

• Poor response to antibiotics

🔹 Acanthamoeba

• PHMB, chlorhexidine, propamidine

• Very long treatment course

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⚠️ Complications

• Corneal scarring

• Perforation

• Secondary glaucoma

• Endophthalmitis

• Vision loss

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👁️‍🗨️ Prevention

• Proper contact lens hygiene

• Avoid eye rubbing

• Use protective eyewear during high-risk activities (e.g. sports, farming, welding)

• Early treatment of dry eye and blepharitis

• Manage underlying systemic diseases (e.g. autoimmune)

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🧠 Mnemonic: "K-E-R-A-T-I-T-I-S"

• Keratitis

• Etiologies: bacteria, virus, fungus, parasite

• Red eye

• Anterior chamber reaction (± hypopyon)

• Tearing and pain

• Infiltrate (seen on slit lamp)

• Topical antimicrobials

• Irritated photophobic eye

• Scar risk if untreated

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Would you like:

• A visual summary chart for types and treatment?

• A flowchart for differential diagnosis of red eye?

• A case-based quiz to test understanding?