Case Study: June 2011

History

  • 70 Yr old male
  • 2yr history of fluctuating blurred vision (L>R)
  • No history of trauma or surgery
  • Slit lamp – superficial corneal opacity in each eye (Fig 1)
  • Underwent excimer laser phototherapeutic keratectomy
  • VA improved to 6/9 (6/6 pinhole)
  • Epithelium sent for histology

Questions

  1. What is the main abnormality in Figure 2 (arrows)?
  2. What do the transmission electron micrographs show in figures 3 and 4?
  3. What is the diagnosis?
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  1. Excessive basement membrane that is indenting the under surface of the epithelium.
  2. Fibrillo-granular electron dense material between the epithelium and Bowman’s.
  3. Epithelial basement membrane dystrophy of bleb type.

Comment

IC3D Classification of EBMD-Most cases have no inheritance documented. Many are considered to be degenerative or secondary to trauma. Familial cases have been reported. Present in adult life. Rarely seen in children.4 subsets: Map, dot, fingerprint and bleb types.

Light microscopy features:

  • Map: Sheets of intraepithelial, multilamellar, basal laminar material.
  • Fingerprint: Rib-like intraepithelial extensions of basal laminar material.
  • Dot: Intraepithelial pseudocyst containing cytoplasmic debris.
  • Bleb: Irregular, subepithelial accumulation of a fibrillogranular material.

Transmission Electron Microscopy features:

  • Map: Thick epithelial basement membrane that extends into the epithelium as multilamellar, 2- to 6-nm-thick sheets.
  • Fingerprint: Fine fibrillogranular substance in addition to basement membrane. The fibrils are about 17 nm in diameter and the granular material about 8 nm.
  • Dot: Intraepithelial pseudocyst contains degenerating cells with pyknotic nuclei and cytoplasmic debris.
  • Bleb: The anterior surface of this material forms discrete mounds, which dent the overlying basal epithelial cells.

References

Bron, A. J. and Brown, N. A. Some superficial corneal disorders. Transactions of the Ophthalmological Society of the United Kingdom, 1971, 92, 13.

Dark AJ. 1977. Bleb dystrophy of the cornea: Histochemistry and ultrastructure. British Journal of Ophthalmology, 1977, 61, 65-69.