Interstitial Keratitis
👁️ Interstitial Keratitis (IK) is corneal inflammation affecting the stroma (middle corneal layer), sparing the epithelium and endothelium.
It can lead to stromal haze, vascularisation, opacification and, if untreated, significant visual impairment.
🦠 Causes
- Infectious:
- 🧬 Syphilis – most common (esp. congenital syphilis).
- 🦠 Herpes simplex virus (HSV) – recurrent stromal keratitis.
- 🤲 Leprosy – chronic corneal inflammation.
- 🕷️ Lyme disease – ocular involvement possible.
- 🧪 Others: TB, EBV, mumps, measles, herpes zoster.
- Non-infectious:
- 🔄 Autoimmune: Sarcoidosis, RA, GPA, PAN.
- ❓ Idiopathic (no identifiable cause).
🔎 Clinical Features
- 👁️ Red, painful eye.
- 🌞 Photophobia.
- 👓 Blurred vision due to stromal haze/opacity.
- 💧 Tearing, ocular discomfort.
- 🧪 Corneal oedema, stromal infiltrates on slit-lamp.
🧪 Investigations
- 🧬 Serology: Syphilis (VDRL/TPHA), Lyme, TB, others.
- 🖐️ Corneal sensitivity: reduced in HSV keratitis.
- 📷 Imaging: Anterior segment OCT to assess stromal involvement.
- 🔦 Slit-lamp: Stromal haze, infiltrates, vascularisation.
⚖️ Differential Diagnoses
- Infectious: Syphilis, TB, Lyme, HSV, VZV, EBV, leprosy, chlamydia.
- Inflammatory/autoimmune: GPA, PAN, RA, relapsing polychondritis, sarcoidosis, Cogan’s syndrome.
- Neoplastic/infiltrative: Ocular lymphoma.
💊 Management
- 🧬 Target infection:
- Syphilis → IV penicillin or doxycycline.
- HSV → Oral aciclovir / valaciclovir.
- Other bacterial causes → appropriate systemic antibiotics.
- 🔥 Reduce inflammation: Topical corticosteroids (careful use, always alongside antimicrobials if infection suspected).
- ⚖️ Treat underlying disease: e.g. immunosuppression for autoimmune disease.
- 🔄 Monitor complications: Secondary glaucoma, corneal scarring.
📈 Prognosis
- ✅ Early treatment → good visual outcome.
- ⚠️ Untreated/severe cases → corneal scarring, vascularisation, chronic visual loss.
- 🔁 Regular follow-up needed to monitor for recurrence.
