Railroad track image characteristic of
posterior polymorphous dystrophy

ICD-10 Diagnosis Code:

H18.59–Posterior polymorphous dystrophy


Posterior Polymorphous Dystrophy


Corneal Opacity And Other Disorders Of Cornea


A form of corneal dystrophy characterized by a metaplasia of endothelial cells.

Posterior polymorphous dystrophy is an uncommon corneal endothelial dystrophy that is typically congenital. However, it can also be recessive and have a later onset.  It usually occurs bilaterally, but often asymmetrically.

Posterior polymorphous dystrophy in most cases is inherited as a autosomal dominant, bilateral and asymmetric disease.  In this condition, the corneal endothelium is often multilayered and has several other characteristics of the corneal epithelium:

  • Multilaminal pattern
  • Desmosomal junctions
  • Microvillus projections
  • Cynplasmic keratin
  • Sparse Mitochonoria
  • Rapid growth in tissue culture

Structural Damage to the Eye

Endothelial Metaplasia 

  • Band-like lesions at the level of Descemet’s membrane
  • Posterior corneal vesicular lesions
  • Islands of abnormal endothelial cells surrounded by normal-appearing cells

Iridocorneal Adhesions 

  • Fine, broad-based adhesions seen only on gonioscopy
  • Large adhesions associated with a glass-like membrane seen on biomicroscopy

Functional Damage to the Eye

  • None (asymptomatic)
  • Photophobia 
  • Decreased vision

The main goal of the diagnostic evaluation in a patient with posterior polymorphous dystrophy is to accomplish the following:

  • Make correct diagnosis
  • Rule out secondary glaucoma 
  • Rule out corneal edema
  • Prescribe a treatment program

Patient History

The severity of the symptoms depends upon the intensity of the presentation.  In severe cases, ocular pain associated with epithelial edema may be present.  

  • None
  • Sensitivity to light
  • Fluctuation vision
  • Decreased vision
  • Foreign body sensation
  • Eye pain

Clinical Appearance of the Cornea

DG37158Pic03a Posterior Corneal Lesions of Variable Morphology

  • Posterior border of cornea appears grayish in color
  • Mild loss of stromal transparency
  • Band-like lesions at the level of Descemet’s membrane
DG37158Pic01a Posterior Corneal Lesions of Variable Morphology

  • Posterior corneal vesicles and opacities in a horizontal band known as a “railroad track” image seen inferiorly
  • Posterior corneal vesicles and opacities in a polymorphous configuration seen superiorly


External Ocular Photography

  • To document the progress or lack of progress of posterior polymorphous dystrophy
  • To document the delivery of treatment of posterior polymorphous dystrophy

Specular Endothelial Microscopy

  • To document the progress or lack of progress of corneal edema
  • To document the delivery and response to medical treatment
  • To help plan a treatment program
  • To document the progress or lack of progress of a corneal endotheliopathy
  • To visualize and analyze the corneal endothelium
SM1 Right Eye

  • Mild pleomorphism
  • Normal corneal thickness

Left Eye

  • Low endothelial cell count
  • Abnormal Descemet’s layer
  • Islands of abnormal endothelial cells surrounded by normal-appearing cells
  • Normal corneal thickness

Corneal Topopgraphy

  • Document the shape and physical features of the anterior corneal surface
  • Identification and follow-up for corneal disease causing irregular astigmatism
  • To help plan a treatment program
  • To document the progress or lack of progress of keratoconus
  • To document the delivery of medical treatment
  • To document the response to treatment
DG37158Pic05 Surface Corneal Astigmatism

  • Right eye has no significant astigmatism and 20/20 best-corrected visual acuity
  • Left eye has regular limbal astigmatism and 20/30 best-corrected visual acuity

There is no classification system for posterior polymorphous dystrophy.

DG37158Pic10 Anterior Basement Membrane Dystrophy

  • Basement membrane dystrophy is characterized by abnormal quantities of basement membrane and cytoplasmic debris that are misdirected into the corneal epithelium
  • Clinically, the abnormal deposits appear as dot-like opacities, map-like patterns, or whorled fingerprint-like lines in the corneal epithelium
  • In many patients, the epithelial lesions change in appearance, location and number over time
DG37158Pic07 Iatrogenic Corneal Endotheliopathy

  • Endothelial damage caused by cataract surgery
  • Surgical trauma generally results in a 4-10% loss of cells
  • Risk factors for a higher percentage of postoperative cell loss include preexisting endothelial disease, diabetes, glaucoma, shallow anterior chamber and previous ocular surgery
DG37158Pic08 Fuchs’ Endothelial Dystrophy

  • 52-year-old white female
  • 20/25 best corrected visual acuity
  • Stage 4 corneal guttata
PDG37158Pic09 Inflammation-Induced Corneal Endotheliopathy

  • 47-year-old black female
  • Chronic uveitis (2-month duration)
  • 20/40 best corrected visual acuity
  • Posterior synechiae visible with pupilary dilation

The first goal of treating patients with posterior polymorphous dystrophy is to reduce complications.

Preventative Treatment

  • Avoiding or minimizing contact lens wear in patients with preexisting epithelial disease 

Pharmocologic Treatment


  • The goal of treatment is to improve visual acuity by deturgescence of the stroma or epithelium.  Compliance with topical hyperosmotic solutions can be challenging due to the burning sensations they often produce. Nighttime application of hyperosmotic ointment is an excellent if not preferred treatment.

Artificial Tears (FreshKote Ophthalmic Solution)

  • The goal of treatment is to remove excess water from the epithelium by utilizing the high oncotic pressure of the solution

Mechanical Treatment

  • Bandage contact lenses — in patients with posterior polymorphous dystrophy, overnight wear of soft contact lens can be used to decrease pain and improve visual acuity

Surgical Treatment 

  • Amniotic membrane allograft
  • Debridement/superficial keratectomy
  • Debride the cornea with a blunt Kimura spatula
  • Smoothing the basement membrane with a diamond burr
  • Excimer laser phototherapeutic keratectomy 

Amniotic Membrane Inserts

ProKera Amniotic Membrane Insert

  • Cryopreserved amniotic membrane graft fastened to a thermoplastic symblepharon ring
  • The device acts as a self-retaining biological bandage
  • Promotes reepithelialization
BioDOptix Amniotic Membrane Insert

  • Dehydrated amniotic membrane graft


It should be noted that the underlying pathophysiology of EBMD lies in the basement membrane.  Simple debridement of the epithelium does little to solve this problem, more likely just resetting the clock for future epithelial breakdown.  Polishing the basement membrane with a diamond burr or photoablative removal of the defective basement membrane will produce far more effective and longer lasting benefits.

1.  Medscape. Posterior Polymorphous Corneal Dystrophy. Available at http://emedicine.medscape.com/article/1197057-overview. Accessed March 24, 2014.
2.  Mejia LF, Aristizabal D, Palacio JM, Callie NL.  Posterior polymorphous dystrophy and keratoconus: more than a casual association? J Emmetropia 2011; 2: 115-119.
3.  Dohm K.  Differential Diagnosis Key To Managing Posterior Polymorphous Dystrophy.  Primary Care Optometry News.  2014 July; 19(7): 18.  http://www.healio.com/optometry/retina-vitreous/news/print/primary-care-optometry-news/%7Bff8f8ff7-715b-4452-a9f3-7bce34c472fc%7D/differential-diagnosis-key-to-managing-posterior-polymorphous-dystrophy.  Last accessed August 9, 2014.

Other posterior corneal dystrophies

External ocular photography

Specular endothelial microscopy

Corneal pachymetry

Anterior segment imaging


Bandage contact lens

Amniotic membrane placement


  • Age of onset is difficult to determine
  • Some patients may present at birth with congenital disease, exhibiting advanced disease with corneal edema
  • Presentation in adulthood is indicative of a more stable disease state with a decreased probability of progression to corneal decompensation
  • Most patients with significant symptoms present at age 25-50 years

  • Prevalence in the general population is unknown

Risk Factors

  • Keratoconus
  • Alport syndrome
  • Family history