Eye Banking and Corneal Transplantation

Eye Banking and Corneal Transplantation

Eye Banking and Corneal Transplantation

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Eye Banking - Cornea Collection Crew

  • Act: THOTA, 1994 (Transplantation of Human Organs and Tissues Act).
  • Donor Criteria:
    • Age: Generally >2 years; no absolute upper limit.
    • Contraindications (Absolute):
      • Systemic: HIV, active Hepatitis B/C, Rabies, Sepsis, CJD, active Leukemia/Lymphoma, death from unknown cause.
      • Ocular: Active infections (e.g., endophthalmitis), Retinoblastoma, Uveal melanoma.
  • Time Limits:
    • Enucleation (eye removal): Ideally <6 hours post-mortem.
    • Corneal excision & preservation: Within 12 hours of death.
  • Corneal Preservation:
    • Storage Temperature: 2-8°C.
    • Media & Duration:
      • M-K Medium (McCarey-Kaufman): Stores for ~4 days.
      • K-Sol, Cornisol: Stores for ~7-10 days.
      • Optisol-GS: Stores for ~10-14 days (contains Chondroitin sulfate, Dextran). 📌 OptiSOL-GS.
  • Evaluation: Specular microscopy; Endothelial Cell Count (ECC) minimum >2000 cells/mm².

⭐ Minimum acceptable endothelial cell density for a donor cornea is >2000 cells/mm²; >2500 cells/mm² is preferred for better graft survival.

Specular microscopy of corneal endothelium

Corneal Transplantation - Sight Surgery Secrets

  • Indications: Optical (keratoconus, scars), tectonic (perforation), therapeutic (keratitis), cosmetic.
  • Contraindications: Active infection, unsuitable donor tissue.
  • Pre-op: Slit-lamp, IOP, endothelial count, donor screening.
  • Surgical Overview:
    • PKP: Full-thickness graft sutured.
    • DALK: Anterior stroma replaced.
    • DSEK/DMEK: Endothelial layer replaced, air/gas tamponade.
TypeLayers ReplacedAdvantagesDisadvantagesKey Indications
PKPFull thicknessVersatileHigh astigmatism, ↑rejection, open skyFull thickness scars, advanced keratoconus
DALKStroma (Endothelium intact)↓Rejection, stronger globeTechnically hard, interface hazeKeratoconus, stromal scars (good endothelium)
DSEKEndothelium, DM, post. stromaFaster recovery (vs PKP), less astigmatismInterface issues, thicker graftFuchs' dystrophy, PBK
DMEKEndothelium, Descemet's Membrane (DM)Best VA, rapid recovery, ↓↓rejectionVery challenging, rebubblingFuchs' dystrophy, PBK (early/moderate)

⭐ DMEK offers the best anatomical restoration and lowest rejection rates among endothelial keratoplasty procedures.

Post-Op & Complications - Graft Guardianship

  • Post-operative Care:

    • Topical steroids (tapered), antibiotics, cycloplegics.
  • Early Complications (<4 wks):

    • Wound leak, shallow AC, infection, ↑IOP.
  • Late Complications (>4 wks):

    • Astigmatism, suture issues, glaucoma, disease recurrence.
  • Graft Rejection: 📌 RSVP signs: Redness, Sensitivity to light, Vision ↓, Pain.

    • Types, Features & Management Hints:
      • Epithelial: Rejection line. Manage: Intensive topical steroids.
      • Stromal: Infiltrates (Krachmer spots). Manage: Topical +/- systemic steroids.
      • Endothelial: Khodadoust line, KPs, edema. (Most common & serious). Manage: Aggressive topical, systemic, periocular steroids (e.g., Prednisolone acetate 1% hourly, IV Methylprednisolone 500mg-1g).

⭐ Endothelial rejection, often with a Khodadoust line, is most common and vision-threatening, needing aggressive steroid therapy.

  • Graft Failure:
    • Primary: Non-viable donor; graft never clears.
    • Secondary: Initially clear graft opacifies (e.g., rejection, endothelial decompensation).
  • Transplantation of Human Organs Act (THOTA) 1994 & amendments: Regulates organ donation, including eyes; defines brain death; outlines procedures for eye retrieval.
  • National Programme for Control of Blindness and Visual Impairment (NPCBVI): Promotes eye donation, supports eye banking infrastructure, and aims to reduce blindness.
  • Hospital Cornea Retrieval Program (HCRP): Proactive approach to identify potential donors in hospitals.
  • Eye Bank Association of India (EBAI): Standardizes eye banking practices, training, and promotes eye donation.
  • Key Procedures: Informed consent (donor/family); grief counselling for donor families.
  • Awareness: Eye Donation Fortnight (Aug 25 - Sep 8); public education campaigns.

THOTA 1994 is the primary legislation governing all organ (including eye) donation and transplantation activities in India, ensuring ethical practices and preventing commercial dealings in organs. It was significantly amended in 2011 to streamline processes and broaden the scope of donation, including from deceased donors after cardiac death in specific circumstances for certain tissues like cornea and skin.

High‑Yield Points - ⚡ Biggest Takeaways

  • McCarey-Kaufman (MK) medium is standard for corneal preservation, storing corneas for 4 days at 4°C.
  • Ideal enucleation: within 6 hours post-mortem. Optisol-GS extends storage to 14 days.
  • Contraindications: HIV, Hepatitis B/C, Rabies, Septicemia, intrinsic eye malignancies.
  • Penetrating Keratoplasty (PKP) is a full-thickness corneal replacement.
  • Minimum donor endothelial cell count: 2000 cells/mm² for graft survival.
  • Endothelial rejection is the most common type of corneal graft rejection.

Practice Questions: Eye Banking and Corneal Transplantation

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Flashcards: Eye Banking and Corneal Transplantation

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