Infectious Systemic Diseases

Bacterial Blight - TB & Syphilis Eyes

• Ocular Tuberculosis (TB):
  • Most common: Posterior uveitis (choroiditis, retinal vasculitis).
  • Choroidal tubercles: Creamy-yellow, deep lesions; may be single or multiple.
  • Eales disease: Peripheral retinal periphlebitis, often bilateral; associated with tuberculoprotein hypersensitivity.
  • Phlyctenular keratoconjunctivitis: Type IV hypersensitivity reaction.
  • Treatment: Standard Anti-Tubercular Therapy (ATT) + Corticosteroids (for inflammation).
• Ocular Syphilis ("The Great Imitator"):
  • Most common: Uveitis (anterior, intermediate, posterior, or panuveitis).
  • Congenital: "Salt & pepper" fundus, interstitial keratitis (Hutchinson's triad component).
  • Neurosyphilis: Argyll Robertson pupil.
  • Acquired: Interstitial keratitis, chorioretinitis, optic neuritis.
  • Treatment: Penicillin (dosage varies by stage and neurosyphilis presence).

⭐ Argyll Robertson pupil (ARP) in neurosyphilis: Characterized by Light-Near Dissociation. 📌 Mnemonic: ARP - Accommodation Reflex Present, Pupillary (Light) Reflex Absent ("Prostitute's Pupil" - accommodates but doesn't react).

Viral Visions - HIV & Herpes Hits

• HIV/AIDS:

  • CMV Retinitis:

    • Most common opportunistic ocular infection. CD4 < 50 cells/µL (high risk), < 100 (moderate risk).
    • Fundus: "Cottage cheese & ketchup" or "pizza pie" appearance (hemorrhages, yellow-white infiltrates).
    • Progresses to retinal necrosis, detachment if untreated.

  • HIV Retinopathy: Non-infectious microvasculopathy. Cotton wool spots, retinal hemorrhages. Common.

  • Others: Kaposi sarcoma (eyelid/conjunctiva), Molluscum contagiosum, increased HZO risk.

• Herpes Viruses:

  • HSV: Keratitis (dendritic ulcer 📌 pathognomonic), uveitis, Acute Retinal Necrosis (ARN).
  • VZV (HZO): Hutchinson's sign 📌 (vesicles on nose tip/side) strongly predicts ocular involvement. Keratitis, uveitis, neuralgia.

⭐ CMV retinitis is the most common opportunistic ocular infection in AIDS, typically occurring when CD4 count < 50 cells/µL.

Fungal Focus - Mucor & Candida Chaos

• Mucormycosis (Zygomycosis)
  • Risks: Diabetes (esp. DKA), immunosuppression, deferoxamine therapy, trauma.
  • Key Presentation: Rhino-orbital-cerebral mucormycosis (ROCM) is most common; look for black necrotic eschar (nasal/palatal), proptosis, ophthalmoplegia, facial pain/numbness, vision loss.
  • Microscopy: Broad, non-septate (aseptate) hyphae with wide-angle (often 90°) branching.
  • Management: Urgent surgical debridement + systemic IV Amphotericin B (liposomal preferred).
• Candida Infections
  • Risks: IV drug use, indwelling catheters, TPN, broad-spectrum antibiotics, immunosuppression, recent major surgery.
  • Ocular: Endogenous endophthalmitis; chorioretinitis presenting as fluffy, white, deep retinal or subretinal lesions (“cotton ball” opacities), often with vitritis.
  • Management: Systemic antifungals (e.g., Fluconazole, Voriconazole); intravitreal antifungals (Amphotericin B or Voriconazole) for significant vitritis/endophthalmitis.

⭐ Rhino-orbital-cerebral mucormycosis (ROCM) is an aggressive, life-threatening fungal infection often seen in diabetic ketoacidosis (DKA) patients, characterized by black necrotic eschar in the nasal cavity or palate and rapid progression if untreated.

Parasite Plight - Toxo & Cystic Curses

• Ocular Toxoplasmosis: Toxoplasma gondii infection.
  • Key: Necrotizing chorioretinitis.
    • Active: "Headlight in fog" (vitritis, fluffy lesion).
    • Inactive: Pigmented scar; satellite lesions common.
  • Congenital (common): 📌 Sabin's triad (chorioretinitis, hydrocephalus, intracranial calcifications).
  • Diagnosis: Clinical; serology (IgG/IgM), PCR (aqueous/vitreous).
  • Rx: Triple therapy (Pyrimethamine + Sulfadiazine + Corticosteroids).
• Ocular Cysticercosis: Taenia solium larvae (Cysticercus cellulosae).
  • Sites: Subretinal (most common), vitreous, anterior chamber, orbit.
  • Intraocular: Translucent cyst ± visible scolex.
  • Orbital: Proptosis, diplopia, myositis.
  • Diagnosis: Clinical, B-scan, CT/MRI (co-existing neurocysticercosis).
  • Rx: Surgery (intraocular); Albendazole + steroids (orbital/adjunct).

⭐ In ocular toxoplasmosis, reactivation often occurs at the border of an old pigmented scar, leading to a satellite lesion.

High‑Yield Points - ⚡ Biggest Takeaways

• Tuberculosis commonly causes choroidal tubercles and uveitis; Eales disease is a sequela.
• Leprosy features madarosis, lagophthalmos, corneal anesthesia, and iris pearls.
• Syphilis ("great masquerader") can cause interstitial keratitis (congenital) and Argyll Robertson pupil.
• CMV retinitis ("pizza pie" appearance) is key in AIDS (CD4 <50).
• Toxoplasmosis presents as focal necrotizing retinochoroiditis ("headlight in fog").
• Herpes Zoster Ophthalmicus shows Hutchinson's sign, indicating higher risk of ocular involvement.
• Dengue fever can lead to maculopathy and retinal hemorrhages.