Pellucid marginal corneal degeneration 12 years after penetrating keratoplasty for keratoconus

Purpose. To report visually disabling postkeratoplasty astigmatism occurring 12 years after a corneal transplant for keratoconus apparently caused by pellucid marginal corneal degeneration (PMD). Methods. A 33-year-old woman had had a corneal transplant for keratoconus in her left eye. Twelve years later, she was referred for evaluation and management of increasingly blurred vision due to marked postkeratoplasty astigmatism. Results. The donor cornea protruded over a region of thinning, anterior to and concentric with a thinned inferior wound. Videokeratoscopy showed +18.35 D of astigmatism in the 34 degrees meridian and inferior corneal steepness surrounding the region of inferior flatness. Conclusion. To our knowledge, this is the first case of apparent PMD occurring after corneal transplantation for keratoconus. The presence of subtle biomicroscopic and keratoscopic signs of PMD prior to corneal transplantation for keratoconus may affect the planned surgical approach.