Eye Infections: Etiological Agents and Diagnosis

Etiological Agents of Eye Diseases

• Etiological agents affecting the eyes vary depending on the area and type of tissue affected
• Disease spread can be divided into four categories:
  • Eyelids and surrounding tissue
  • Conjunctiva
  • Cornea
  • Intraocular area

Blepharitis

• Etiological agent: Demodex folliculorum (a mite) followed by bacterial infection Staphylococcus aureus or Staphylococcus epidermidis
• Diagnosis: allergic reaction to the mite residing in eyelash or eyebrow follicles
• Treatment:
  • Glucocorticoid for allergic reaction
  • Doxycycline or Minocycline (contra-indicated in children and pregnant women)
  • Azithromycin (alternative)

Hordeolum and Chalazion

• Etiological agents:
  • Staphylococcus aureus
  • Pseudomonas aeruginosa
  • Proteus sp.
• Diagnosis:
  • Obstruction of gland orifice (Meibomian, Zeis, or Moll)
  • Red, painful nodule with yellowish top
  • Acute suppurative inflammation
• Treatment:
  • Erythromycin for susceptible strains and prevention of corneal and conjunctival infections
  • Cephalexin for acute hordeolum
  • Doxycycline for recurrent lesions or significant meibomitis
• Chalazion evolves from hordeolum that do not drain spontaneously or are not incised
• Chronic inflammation and granuloma formation may occur

Acute Dacryocystitis

• Etiological agents:
  • Staphylococcus aureus
  • Staphylococcus epidermidis
  • Streptococcus pneumoniae
• Treatment:
  • Coamoxiclav
  • Sultamicillin
  • Levofloxacin
  • Tobramycin ophthalmic
  • Tobramycin plus dexamethasone ophthalmic
• Diagnosis:
  • Infection of lacrimal sac secondary to obstruction of lacrimal duct
  • Pain in tear sac area
  • Erythema, edema, purulent discharge, and epiphora

Chronic Dacryocystitis

• Etiological agents:
  • Streptococcus pneumoniae
  • Hemophilus influenzae
  • Candida albicans
  • Aspergillus spp.
  • Actinomyces spp.
• Treatment:
  • Topical sulfacetamide
  • Erythromycin
  • Ciprofloxacin
  • Gatifloxacin
  • Ofloxacin
  • Besifloxacin (new agent)
• Diagnosis:
  • Chronic conjunctivitis
  • Severe corneal inflammation
  • Isolation of Gram-negative slender rod

Ocular Lymphogranuloma Venereum

• Etiological agent: Chlamydia trachomatis
• Diagnosis:
  • Chlamydial disease transmitted during birth
  • Inflammation begins 5 days after birth
  • Corneal scars, conjunctival scars, and micro pannus formation
  • Inclusions in epithelial cells of the conjunctiva
• Treatment:
  • Azithromycin
  • Erythromycin
  • Doxycycline (DOC, but caution in children)

Trachoma

• Etiological agent: Chlamydia trachomatis
• Diagnosis:
  • Limited to epithelial cells of the eye and nasopharynx
  • No systemic involvement
  • Worldwide distribution
  • Greatest single cause of blindness