Laser scanning in vivo confocal microscopy in a case of Terrien marginal degeneration

To describe corneal microstructural modifications in an early case of Terrien marginal degeneration by means of laser scanning in vivo corneal confocal microscopy.

A 20-year-old man affected by Terrien marginal degeneration in his right eye was examined with the Heidelberg Retina Tomograph 2 with a Rostock Cornea Module. The patient presented a corneal lesion with marked superior thinning and no clinical signs of inflammation. The left eye showed no clinical signs of degeneration.

The right eye showed irregular Bowman's membrane, amorphous-appearing substance co-localizing with lipid exudation, and needle-like hyperreflective material in the affected peripheral corneal region. Abnormally scarce and branched sub-basal plexus nerves as well as numerous activated keratocytes, sometimes organized in hyperreflective nests, were observed in the central cornea of the same eye. Although the left eye was clinically unaffected, activated keratocytes were detected in its anterior central stroma.

In vivo confocal microscopy supports the hypothesis of a mild inflammatory state with an atypical sub-basal nerve pattern in a patient affected by Terrien marginal degeneration. This new technique shows promise in studying this still elusive pathology.