What is the inheritance pattern of posterior polymorphous corneal dystrophy?

Autosomal dominant with variable expressivity PPCD is a bilateral autosomal dominant dystrophy, and expressivity varies even within one family, so some relatives have only incidental findings while others develop significant disease.

Sporadic, with no familial clustering

What happens to the corneal endothelial cells in posterior polymorphous corneal dystrophy?

They become metaplastic and behave like epithelium The endothelium undergoes metaplastic transformation towards epithelial characteristics, including the capacity to proliferate, which normal adult corneal endothelium essentially cannot do.

They are progressively replaced by fibroblasts

They accumulate abnormal mucopolysaccharide

They are destroyed by lymphocytic infiltration

Which lesions are characteristic of posterior polymorphous corneal dystrophy at the slit lamp?

Vesicular and band lesions at Descemet's level PPCD shows clustered blister-like vesicular lesions and band-like or geographic lesions with scalloped edges at the level of Descemet's membrane and endothelium.

Subepithelial map-like grey lines

Fine branching stromal lattice lines

Central crystalline stromal deposits

What is the usual clinical course for most patients with posterior polymorphous corneal dystrophy?

Asymptomatic, with normal corneal thickness Many patients carry the diagnosis for life without significant visual symptoms and are found incidentally, with normal corneal thickness and a clear visual axis despite the endothelial changes.

Progressive oedema needing a graft in childhood

Early severe glaucoma in nearly all cases

Recurrent painful epithelial erosion episodes

What produces iridocorneal adhesions in more severe posterior polymorphous corneal dystrophy?

Abnormal endothelial tissue extending across the angle The epithelial-like endothelium can grow across the angle, producing peripheral anterior synechiae and, in a meaningful subset, secondary glaucoma from the same angle involvement.

Chronic granulomatous iritis with synechiae

Lens-induced forward displacement of the iris

A neovascular membrane contracting over the angle

How is posterior polymorphous corneal dystrophy distinguished from iridocorneal endothelial syndrome?

PPCD is bilateral and inherited, ICE unilateral and sporadic Severe PPCD shares endothelial and angle features with ICE syndrome, but PPCD is bilateral and inherited while ICE syndrome is characteristically unilateral, sporadic and presents in adulthood.

PPCD affects one eye only, while ICE is always bilateral

PPCD spares the angle entirely, whereas ICE involves it

PPCD becomes apparent only after the age of sixty

Which feature separates Fuchs endothelial corneal dystrophy from posterior polymorphous corneal dystrophy?

Guttae with a beaten-metal appearance Fuchs dystrophy shows guttae with a beaten-metal appearance and progressive age-related endothelial cell loss, typically with later onset than the vesicular and band lesions of PPCD.

Vesicular lesions grouped into small clusters

Band-like endothelial lesions with scalloped edges

Peripheral anterior synechiae across the angle

Which assessments belong in routine follow-up of a patient with extensive posterior polymorphous corneal dystrophy?

Gonioscopy and intraocular pressure monitoring Because angle involvement and secondary glaucoma are recognised risks in more extensive disease, gonioscopy and pressure checks should be routine rather than reserved for symptomatic patients.

Corneal topography and keratometry

Dilated fundus examination and macular OCT

Lacrimal irrigation and Schirmer testing

How is visually significant corneal oedema from posterior polymorphous corneal dystrophy treated?

Topical corticosteroid with cycloplegia

Why are relatives of a patient with posterior polymorphous corneal dystrophy offered a slit-lamp examination?

Dominant inheritance means relatives may be mildly affected Given the dominant pattern and variable expressivity, screening can identify mildly affected relatives even without symptoms, which supports informed family planning and clarifies recurrence risk.

The condition spreads through shared contact lens use

Screening is required to exclude an infectious source

Every carrier eventually needs a corneal transplant

Posterior Polymorphous Corneal Dystrophy

Posterior polymorphous corneal dystrophy (PPCD) is a bilateral, autosomal dominant endothelial dystrophy notable for how variable its clinical impact is: many affected individuals carry the diagnosis for life without ever developing significant visual symptoms, discovered only incidentally on a slit-lamp exam performed for another reason, while a smaller subset develop progressive corneal edema or glaucoma requiring active treatment.

This wide range of severity, more than almost any other single feature, is what shapes how the condition is actually managed in practice, since the same genetic diagnosis can mean lifelong observation for one patient and active treatment for another.

What Makes PPCD Different From Other Endothelial Dystrophies

Unlike Fuchs endothelial corneal dystrophy, discussed in its own dedicated article on this site, where the endothelium progressively loses cells and function over years, the corneal endothelial cells in PPCD undergo an unusual metaplastic transformation, taking on characteristics more typical of epithelial cells, including the capacity to proliferate, which normal corneal endothelium essentially cannot do in adults.

This abnormal, epithelial-like behavior of the endothelial layer is the fundamental biological difference underlying PPCD’s distinctive appearance and, in its more severe presentations, its capacity to grow across and functionally compromise adjacent structures including the trabecular meshwork.

Clinical Findings

Vesicular lesions — small, round, blister-like changes at the level of Descemet’s membrane and endothelium, often grouped in clusters
Band-like or geographic lesions with scalloped edges, another characteristic pattern seen at the same corneal level
Diffuse, gray, hazy opacification of Descemet’s membrane in some patients
Most patients are asymptomatic, with normal corneal thickness and clarity to the visual axis despite the presence of these endothelial changes on careful exam
A subset of patients develop corneal edema, sometimes significant, related to genuine endothelial dysfunction rather than simply the presence of the characteristic lesions themselves
Iridocorneal adhesions (peripheral anterior synechiae) in more severe cases, related to the abnormal endothelial tissue extending across the angle — a feature that begins to overlap conceptually and clinically with iridocorneal endothelial (ICE) syndrome, discussed in its own dedicated article on this site, though PPCD is bilateral and inherited while ICE syndrome is characteristically unilateral and sporadic
Secondary glaucoma, in a meaningful subset of more severely affected patients, from the same angle involvement described above

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Differential Diagnosis

Fuchs endothelial corneal dystrophy — guttae with a “beaten metal” appearance and progressive, age-related endothelial cell loss, a different pattern and typically later onset than the vesicular/band lesions of PPCD present from a much younger age, discussed in its own dedicated article on this site
Iridocorneal endothelial (ICE) syndrome — shares some overlapping endothelial and angle features with more severe PPCD, but is unilateral, sporadic (not inherited), and typically presents in adulthood rather than being present, even if subclinically, from a much earlier age
Congenital hereditary endothelial dystrophy — presents with dense, diffuse corneal clouding from birth, a far more severe and immediately apparent presentation than the typically subtle, often asymptomatic findings of PPCD, discussed in its own dedicated article on this site
Corneal guttae as a purely incidental, non-progressive finding — distinguished from true PPCD by the specific vesicular or band pattern and, when genetic testing is pursued, the relevant gene involvement

Posterior Polymorphous Corneal Dystrophy: clinical photograph, second view

Genetics

PPCD is genetically heterogeneous, with mutations identified in several genes (including ZEB1, COL8A2, and others depending on the specific subtype), inherited in an autosomal dominant pattern with variable expressivity even within the same family.

Some relatives carrying the same mutation may show minimal, incidental findings while others develop clinically significant disease, similar in spirit to the variable expressivity discussed in this site’s coverage of dominant optic atrophy, another autosomal dominant condition where family members can be affected to different degrees.

Diagnostic Evaluation

The characteristic vesicular and band-like lesions are usually identifiable on careful slit-lamp examination with specular reflection.

Specular microscopy, where available, can further characterize the abnormal endothelial cell morphology.

Gonioscopy and intraocular pressure monitoring are important in patients with more extensive disease, given the recognized risk of secondary angle involvement and glaucoma in this subgroup, and should be incorporated into routine follow-up for these patients rather than reserved only for those with obvious symptoms.

Family screening can be informative given the autosomal dominant inheritance and variable expressivity described above.

Management

Most patients, given how often the disease remains mild and asymptomatic, require no treatment beyond periodic monitoring, including specific attention to intraocular pressure given the glaucoma risk in more severely affected individuals.

Patients who develop significant corneal edema are managed with the same general approach used for endothelial dysfunction from other causes: hypertonic saline for symptomatic relief in milder cases, and endothelial keratoplasty for more advanced, visually significant edema, following similar principles to those discussed in this site’s coverage of Fuchs endothelial dystrophy.

Secondary glaucoma related to angle involvement is managed with standard glaucoma therapy, medical or surgical depending on severity.

Family members of an affected individual may benefit from screening slit-lamp examination given the dominant inheritance pattern, even in the absence of any visual symptoms, since identifying mildly affected relatives can support informed family planning and clarify recurrence risk for future generations.

References

Weiss JS, Møller HU, Aldave AJ, et al. IC3D classification of corneal dystrophies — edition 2. Cornea.
Krachmer JH. Posterior polymorphous corneal dystrophy: a disease characterized by epithelial-like endothelial cells which influence management and prognosis. Transactions of the American Ophthalmological Society.
American Academy of Ophthalmology. Basic and Clinical Science Course, Section 8: External Disease and Cornea.

Test yourself

A few questions straight from this article.

1 / 10 0 correct

What is the inheritance pattern of posterior polymorphous corneal dystrophy?
PPCD is a bilateral autosomal dominant dystrophy, and expressivity varies even within one family, so some relatives have only incidental findings while others develop significant disease.
What happens to the corneal endothelial cells in posterior polymorphous corneal dystrophy?
The endothelium undergoes metaplastic transformation towards epithelial characteristics, including the capacity to proliferate, which normal adult corneal endothelium essentially cannot do.
Which lesions are characteristic of posterior polymorphous corneal dystrophy at the slit lamp?
PPCD shows clustered blister-like vesicular lesions and band-like or geographic lesions with scalloped edges at the level of Descemet's membrane and endothelium.
What is the usual clinical course for most patients with posterior polymorphous corneal dystrophy?
Many patients carry the diagnosis for life without significant visual symptoms and are found incidentally, with normal corneal thickness and a clear visual axis despite the endothelial changes.
What produces iridocorneal adhesions in more severe posterior polymorphous corneal dystrophy?
The epithelial-like endothelium can grow across the angle, producing peripheral anterior synechiae and, in a meaningful subset, secondary glaucoma from the same angle involvement.
How is posterior polymorphous corneal dystrophy distinguished from iridocorneal endothelial syndrome?
Severe PPCD shares endothelial and angle features with ICE syndrome, but PPCD is bilateral and inherited while ICE syndrome is characteristically unilateral, sporadic and presents in adulthood.
Which feature separates Fuchs endothelial corneal dystrophy from posterior polymorphous corneal dystrophy?
Fuchs dystrophy shows guttae with a beaten-metal appearance and progressive age-related endothelial cell loss, typically with later onset than the vesicular and band lesions of PPCD.
Which assessments belong in routine follow-up of a patient with extensive posterior polymorphous corneal dystrophy?
Because angle involvement and secondary glaucoma are recognised risks in more extensive disease, gonioscopy and pressure checks should be routine rather than reserved for symptomatic patients.
How is visually significant corneal oedema from posterior polymorphous corneal dystrophy treated?
Oedema is managed as endothelial dysfunction from any cause: hypertonic saline for symptomatic relief in milder cases, and endothelial keratoplasty once the oedema is advanced and visually significant.
Why are relatives of a patient with posterior polymorphous corneal dystrophy offered a slit-lamp examination?
Given the dominant pattern and variable expressivity, screening can identify mildly affected relatives even without symptoms, which supports informed family planning and clarifies recurrence risk.