title: Current options in the management of pellucid marginal degeneration.
abstract: OBJECTIVE
  To review and evaluate current and future directions in the diagnosis and surgical management of pellucid marginal degeneration (PMD), including penetrating keratoplasty, full-thickness crescentic wedge resection (FTCWR), deep anterior lamellar keratoplasty (DALK), crescentic lamellar wedge resection (CLWR), crescentic lamellar keratoplasty, tuck-in lamellar keratoplasty (TILK), toric phakic intraocular lens (PIOL) implantation, intrastromal corneal ring segment implantation (ICRS), corneal collagen cross-linking (CXL), and combined therapies. This is the first review article looking at the literature specific to PMD.
  
  
  METHODS
  Review of published studies.
  
  
  RESULTS
  Reported data for each treatment is presented. Penetrating keratoplasty is the treatment of last resort in PMD and is effective, but with considerable complications. DALK provides visual outcomes similar to penetrating keratoplasty without the risk of immune-mediated graft rejection, but its complexity and relative novelty limit its acceptance. FTCWR has good visual outcomes, but with significant astigmatic drift. CLWR is effective, but lacks long-term results. Crescentic lamellar keratoplasty and TILK are effective, but technically difficult and without long-term results. Toric PIOL implantation is effective, but ectasia progression is a concern. ICRS implantation can delay penetrating keratoplasty and improve contact lens tolerance, but does not treat the underlying process. CXL demonstrates effectiveness without complications, although data are limited and long-term results are needed. Combining treatments such as ICRS, CXL, toric PIOL implantation, and refractive surgery is promising, but additional studies are needed to investigate their efficacy and safety.
  
  
  CONCLUSIONS
  Although little is understood about the etiology, pathophysiology, epidemiology, and genetics of PMD, new treatments are improving visual outcomes and reducing complications. Corneal collagen cross-linking is especially exciting because it halts disease progression. Combined treatments and improved screening could eliminate the need for surgical management in most cases of PMD.
authors.forename: Majid
authors.initials: M
authors.lastname: Moshirfar
authors.forename: Jason N
authors.initials: JN
authors.lastname: Edmonds
authors.forename: Nicholas L
authors.initials: NL
authors.lastname: Behunin
authors.forename: Steven M
authors.initials: SM
authors.lastname: Christiansen
mesh_terms: D003316:Corneal Diseases / Q000175:diagnosis* / Q000601:surgery*; D019781:Corneal Topography; D003941:Diagnostic Techniques, Ophthalmological; D004108:Dilatation, Pathologic; D006801:Humans; D013508:Ophthalmologic Surgical Procedures