Which slit-lamp pattern characterizes granular corneal dystrophy?

Diffuse ground-glass haze across the stroma

Branching refractile stromal lines

Endothelial guttae with a beaten-bronze reflex

What material composes the stromal deposits of granular corneal dystrophy?

Hyaline The deposits of granular corneal dystrophy are composed of hyaline material.

How is granular corneal dystrophy inherited?

Autosomal dominant Granular corneal dystrophy follows an autosomal dominant pattern, and a family history consistent with that inheritance supports the clinical diagnosis.

Granular corneal dystrophy arises from mutations in which gene, shared with lattice dystrophy?

TGFBI Granular and lattice dystrophies both arise from mutations in the TGFBI gene, although the specific mutations differ and produce clinically distinct patterns.

At what age does granular corneal dystrophy typically begin?

In the first decade of life Onset is typically in the first decade of life, although the deposits are often small and may not be visually significant until much later.

What does the historical term Avellino corneal dystrophy describe?

A combined granular and lattice deposit pattern Avellino corneal dystrophy, also called granular corneal dystrophy type 2, results from a further specific TGFBI mutation producing overlapping granular and lattice-like features.

Granular deposits confined to the corneal periphery

Granular deposits confined to the endothelium

Granular dystrophy with congenital glaucoma

Which complication is reported after photorefractive keratectomy in granular corneal dystrophy?

Unusually severe and rapid stromal haze Affected patients, especially those with the combined granular-lattice pattern, have been reported to develop unusually severe and rapid stromal haze after photorefractive keratectomy and, less so, after LASIK.

Progressive endothelial cell failure

Spontaneous corneal perforation

Permanent loss of corneal sensation

Which finding makes phototherapeutic keratectomy appropriate in granular corneal dystrophy?

Superficial anterior stromal deposits causing symptoms Excimer laser phototherapeutic keratectomy ablates anterior deposits causing visual symptoms or recurrent erosion, offering a less invasive alternative to full corneal transplantation.

Dense deposits reaching Descemet membrane

Accompanying endothelial decompensation

Deposits detectable only on genetic testing

Which keratoplasty suits deep vision-limiting granular dystrophy with a healthy endothelium?

Deep anterior lamellar keratoplasty When deposits become deep, extensive and vision-limiting, corneal transplantation restores clear central vision, typically as deep anterior lamellar keratoplasty if the endothelium is unaffected.

Descemet membrane endothelial keratoplasty

Boston keratoprosthesis implantation

Descemet stripping endothelial keratoplasty

Why can granular dystrophy deposits recur within a corneal graft?

The deposits arise from the patient's own corneal cells Deposits can recur in donor tissue over years to decades because the metabolic process producing them originates in the patient's own corneal cells, not in the replaced central stroma.

Donor tissue carries the TGFBI mutation

Topical steroids accelerate hyaline deposition

Graft sutures seed hyaline material inward

Granular Corneal Dystrophy: Signs & Treatment

Granular corneal dystrophy produces one of the more visually memorable slit-lamp patterns in corneal disease: discrete, white, crumb-like deposits scattered through an otherwise clear stroma, and the clarity of the tissue between the deposits, in contrast to the diffuse haze of macular dystrophy or the branching lines of lattice dystrophy, is itself a key part of what makes this pattern recognizable.

The Characteristic Appearance

The deposits in granular corneal dystrophy are composed of hyaline material and appear as discrete, sharply demarcated, breadcrumb or snowflake-shaped white opacities scattered predominantly in the central and anterior stroma, with the surrounding stroma between deposits remaining entirely clear, a pattern often described as looking like crumbs scattered on a clean surface.

This is genetically and clinically distinct from lattice corneal dystrophy, despite both arising from mutations in the same TGFBI gene, and the clear intervening stroma is one of the most useful distinguishing features on examination.

Genetics

Granular corneal dystrophy is inherited in an autosomal dominant pattern and results from specific mutations in the TGFBI gene, distinct from the mutations that produce lattice dystrophy, and a combined granular-lattice pattern, historically called Avellino corneal dystrophy, results from yet another specific TGFBI mutation producing overlapping features of both.

Test your knowledge 10 questions from this article

Clinical Course

Onset is typically in the first decade of life, though the deposits are often small and may not be visually significant until later
Slowly progressive, with deposits gradually increasing in number, size, and depth over decades
Vision is often preserved reasonably well for many years, since the clear stroma between deposits allows relatively good optical transmission until the deposits become numerous and confluent enough to significantly scatter light
Recurrent corneal erosion can occur, related to disruption of normal epithelial basement membrane adhesion over areas of deposit, though this tends to be less prominent than in lattice dystrophy
Two clinically distinguished subtypes exist: granular corneal dystrophy type 1, with deposits generally sparing the periphery and a clear intervening stroma, and type 2 (Avellino), which combines granular and lattice-like features and tends to show somewhat different deposit characteristics and progression

Diagnosis

Diagnosis is typically made clinically based on the distinctive slit-lamp appearance of discrete white deposits with clear intervening stroma, combined with a family history consistent with autosomal dominant inheritance.

Genetic testing for the specific TGFBI mutation can confirm the diagnosis and distinguish granular dystrophy from the combined granular-lattice (Avellino) pattern, which carries somewhat different clinical implications, including a reported increased risk of unusual stromal haze following photorefractive keratectomy in affected patients.

Management

Observation

Many patients with granular corneal dystrophy have deposits that remain visually insignificant for years to decades, and observation without intervention is appropriate as long as vision remains adequate for the patient’s needs.

Clinical eye photograph illustrating Granular Corneal Dystrophy Management

Phototherapeutic Keratectomy

For more superficial, anterior stromal deposits causing visual symptoms or recurrent erosion, phototherapeutic keratectomy with the excimer laser can ablate the anterior deposits and improve both surface regularity and visual clarity, offering a less invasive option than full corneal transplantation for appropriately selected patients.

Corneal Transplantation

When deposits become deep, extensive, and significantly vision-limiting, corneal transplantation, typically deep anterior lamellar keratoplasty when the endothelium is unaffected, restores clear central vision.

An Important Caution: Refractive Surgery

Patients with granular corneal dystrophy, and particularly the combined granular-lattice (Avellino) pattern, have been reported to develop unusually severe and rapid stromal haze after photorefractive keratectomy and, to a lesser extent, LASIK, so screening for a family history of corneal dystrophy before refractive surgery, and genetic testing when there is any suspicion, is an important safety step given how serious this specific complication can be.

Recurrence After Transplantation

As with other TGFBI-related stromal dystrophies, granular corneal dystrophy deposits can recur in transplanted donor tissue over years to decades, since the metabolic process producing the deposits originates from the patient’s own corneal cells rather than being eliminated by replacing central stromal tissue alone.

Prognosis

Granular corneal dystrophy generally has a favorable long-term visual prognosis given its typically slow progression and the clear stroma preserved between deposits, and both phototherapeutic keratectomy and corneal transplantation, when eventually needed, are generally effective, though with the recognized possibility of deposit recurrence over the very long term.

References

Weiss JS, Moller HU, Aldave AJ, et al. IC3D classification of corneal dystrophies–edition 2. Cornea. 2015;34:117-159.
Rathi VM, Vyas SP, Sangwan VS. Phototherapeutic keratectomy. Br J Ophthalmol. 2012;96:618-621.
Afshari NA, Mullally JE, Afshari MA, et al. Survey of patients with granular, lattice, avellino, and Reis-Bucklers corneal dystrophies for mutations in the BIGH3 and gelsolin genes. Arch Ophthalmol. 2001;119:16-22.
Dinh R, Rapuano CJ, Cohen EJ, Laibson PR. Recurrence of corneal dystrophy after excimer laser phototherapeutic keratectomy. Ophthalmology. 1999;106:1490-1497.

Test yourself

A few questions straight from this article.

1 / 10 0 correct

Which slit-lamp pattern characterizes granular corneal dystrophy?
The deposits are discrete, sharply demarcated breadcrumb or snowflake-shaped white opacities in the central and anterior stroma, with the stroma between them remaining entirely clear.
What material composes the stromal deposits of granular corneal dystrophy?
The deposits of granular corneal dystrophy are composed of hyaline material.
How is granular corneal dystrophy inherited?
Granular corneal dystrophy follows an autosomal dominant pattern, and a family history consistent with that inheritance supports the clinical diagnosis.
Granular corneal dystrophy arises from mutations in which gene, shared with lattice dystrophy?
Granular and lattice dystrophies both arise from mutations in the TGFBI gene, although the specific mutations differ and produce clinically distinct patterns.
At what age does granular corneal dystrophy typically begin?
Onset is typically in the first decade of life, although the deposits are often small and may not be visually significant until much later.
What does the historical term Avellino corneal dystrophy describe?
Avellino corneal dystrophy, also called granular corneal dystrophy type 2, results from a further specific TGFBI mutation producing overlapping granular and lattice-like features.
Which complication is reported after photorefractive keratectomy in granular corneal dystrophy?
Affected patients, especially those with the combined granular-lattice pattern, have been reported to develop unusually severe and rapid stromal haze after photorefractive keratectomy and, less so, after LASIK.
Which finding makes phototherapeutic keratectomy appropriate in granular corneal dystrophy?
Excimer laser phototherapeutic keratectomy ablates anterior deposits causing visual symptoms or recurrent erosion, offering a less invasive alternative to full corneal transplantation.
Which keratoplasty suits deep vision-limiting granular dystrophy with a healthy endothelium?
When deposits become deep, extensive and vision-limiting, corneal transplantation restores clear central vision, typically as deep anterior lamellar keratoplasty if the endothelium is unaffected.
Why can granular dystrophy deposits recur within a corneal graft?
Deposits can recur in donor tissue over years to decades because the metabolic process producing them originates in the patient's own corneal cells, not in the replaced central stroma.

Ahmed Ophthalmologist

Writes and reviews the clinical articles on Educate. Every post is checked against peer-reviewed sources before it goes live.

Granular Corneal Dystrophy: Breadcrumbs in the Stroma With Clear Windows Between