Corneal Transplantation

Indications & Types - Eye See Clearly Now

Indications for Keratoplasty:

• Optical: Improve vision.
  • Keratoconus, Bullous keratopathy (PBK/ABK), Dystrophies (Fuchs', Macular), Scars.
• Tectonic: Restore corneal integrity.
  • Perforations, Descemetocele, Severe thinning.
• Therapeutic: Remove infected tissue.
  • Unresponsive microbial keratitis (fungal, Acanthamoeba).
• Cosmetic: Disfiguring scars (rare).

Types of Keratoplasty:

• Penetrating Keratoplasty (PKP): Full-thickness graft.
  • For full-thickness opacities, advanced keratoconus.
• Lamellar Keratoplasty (LK): Partial-thickness graft.
  • Anterior (ALK):
    • DALK: Stromal disease, healthy endothelium (e.g., Keratoconus).
  • Posterior/Endothelial (EK):
    • DSAEK/DMEK: Endothelial dysfunction (e.g., Fuchs', PBK).
    • DMEK offers faster recovery, better vision.

⭐ Pseudophakic Bullous Keratopathy (PBK) is a leading indication for penetrating keratoplasty in adults in many regions.

Surgical Techniques - Precision Cuts & Layers

Corneal transplantation (Keratoplasty) involves precise surgical replacement of diseased corneal layers. Choice depends on pathology depth.

• PKP (Penetrating Keratoplasty): Full-thickness graft. For pan-corneal opacities.
• DALK (Deep Anterior Lamellar Keratoplasty): Replaces epithelium & stroma; preserves host endothelium. ↓ Rejection risk.
• DSEK/DSAEK (Descemet's Stripping Endothelial Keratoplasty): Replaces posterior stroma, Descemet's, endothelium. Graft approx. 100-200 µm.
• DMEK (Descemet's Membrane Endothelial Keratoplasty): Replaces Descemet's & endothelium only. Graft approx. 10-20 µm; best anatomical fit.

Graft Rejection - Immune System Showdown

• Host immune response against donor corneal antigens; T-cell mediated (Type IV hypersensitivity).
• Types & Timing:
  • Epithelial: Weeks to months; often reversible; rejection line.
  • Stromal: Months to years; infiltrates (Krachmer spots), edema.
  • Endothelial: Most critical; weeks to years; Khodadoust line (endothelial rejection line), keratic precipitates (KPs), edema. Leads to graft failure if untreated.
• Signs & Symptoms: 📌 RSVP: Redness, Sensitivity to light (photophobia), Vision decreased, Pain.
• Risk Factors: Young recipient, prior rejection, large graft, vascularized host bed, active inflammation.

⭐ Endothelial rejection is the most common type leading to irreversible graft failure.

• Management: Topical corticosteroids (e.g., Prednisolone acetate 1% hourly), systemic steroids, immunosuppressants (e.g., Cyclosporine A). Early detection is key for graft survival. Subconjunctival steroids may be used.

Post-op Care & Complications - Healing & Hurdles

• Post-op Regimen:
  • Topical steroids (e.g., Prednisolone): Slow taper (PKP: ~1 year).
  • Topical antibiotics: 1-2 weeks prophylaxis.
  • Cycloplegics: 1-2 weeks for pain/synechiae.
  • IOP checks: Day 1, Wk 1, Mo 1, then regular.
  • Suture removal (PKP): Selective, 9-12 months, guided by astigmatism.
• Potential Hurdles:
  • Early: Wound leak, infection (keratitis/endophthalmitis), ↑IOP.
  • Late: Graft rejection (endothelial most critical), significant astigmatism, suture-related problems, primary disease recurrence, late endothelial failure.
  • 📌 Rejection signs (RSVP): Redness, Sensitivity to light, Vision ↓, Pain.

⭐ High irregular astigmatism is a common reason for suboptimal vision after Penetrating Keratoplasty (PKP).

High‑Yield Points - ⚡ Biggest Takeaways

• Penetrating Keratoplasty (PKP) replaces full corneal thickness; DALK spares recipient endothelium.
• DSEK/DMEK for endothelial issues like Fuchs' dystrophy, Pseudophakic Bullous Keratopathy (PBK).
• Corneal scars and keratoconus are common indications for PKP/DALK.
• Endothelial rejection is most common, characterized by Khodadoust line and corneal edema.
• Donor corneas stored in Optisol-GS at 4°C; HLA matching not routine.
• Key complications: Graft rejection, high post-operative astigmatism, secondary glaucoma.