Characteristic features of granular deposit formation in granular corneal dystrophy type 2

To describe the characteristic features of white granular deposits associated with granular corneal dystrophy type 2 (GCD2).

Five patients with GCD2 associated with the R124H mutation (2 homozygous GCD2 and 3 heterozygotes) were examined. The corneal deposits of all patients were assessed and reviewed by slit-lamp photographs. Density line profiles of corneal surfaces were evaluated around the discrete corneal deposits using Image J software. A Fourier-domain optical coherence tomography with cornea anterior module was used to visualize the characteristic surrounding features of these granular deposits. A histopathological study of the homozygous corneal specimen obtained after keratoplasty was performed.

Slit-lamp images and densitometry line profiles showed that discrete granules were surrounded by relatively clear areas in all patients. The Fourier-domain optical coherence tomography image clearly showed highly reflective lesions, corresponding to the corneal deposits, surrounded by lower reflective areas. Histopathological study revealed comparable findings to the optical coherence tomography image. Serial comparison of slit-lamp photographs demonstrated a recurrence pattern after penetrating keratoplasty in a homozygous patient and natural progression in a heterozygote patient. They were similar in that diffuse fine granules gradually increased in density and discrete granular deposits also enlarged or were newly formed.

In GCD2, discrete white granular deposits were surrounded by rather lucid areas and fine granular haze. These findings suggest that white granular deposits may be formed by aggregation of surrounding fine granules.