Regarding corneal graft survival in penetrating keratoplasty, the 'high-risk' corneal bed is defined by which criteria according to current guidelines, necessitating systemic immunosuppression?
- A Corneal vascularization in 2 or more quadrants of the donor bed, or prior failed graft ✓
- B Graft diameter >8.5 mm or previous failed graft
- C Chemical burn with total conjunctival stem cell failure
- D Age <30 years with active anterior uveitis
Correct answer: A. Corneal vascularization in 2 or more quadrants of the donor bed, or prior failed graft
Explanation
High-risk penetrating keratoplasty is defined by corneal vascularization reaching the donor bed in 2 or more quadrants, and/or a history of prior failed corneal graft. Vascularization disrupts immune privilege (which depends on avascular cornea, anterior chamber-associated immune deviation, and absence of antigen-presenting cells) by introducing vessels that allow lymphocyte trafficking. In such cases, systemic immunosuppression (oral cyclosporine) is considered in addition to intensive topical steroids to prevent rejection.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.