Pellucid Marginal Degeneration (PMD)

Pellucid Marginal Degeneration (PMD)
SYMPTOMS Blur | Distorted vision | Image ghosting
SIGNS Peripheral corneal thinning and protrusion (usually inferior) | Irregular astigmatism | Topography shows peripheral corneal elevation - 1-2 mm from the limbus
WORK-UP Thorough history. Slit lamp examination. Topography
TREATMENT Mild PMD may be managed visually with glasses and/or soft contact lenses | Moderate-Severe PMD may be better managed with rigid gas permeable or scleral lenses | Progressive PMD should be monitored closely with topography/tomography | Advanced cases may undergo corneal transplantation
FOLLOW-UP Every 6-12 months
DIFFERENTIAL DX Keratoconus | Keratoglobus | Post-LASIK ectasia | Terrien marginal degeneration
NOTES There is no inflammation associated with PMD | Corneal hydrops is an uncommon occurrence | Corneal transplants for PMD usually require a larger graft than KCN procedures, with a higher risk of graft failure