Confocal microscopic evidence of increased Langerhans cell activity after corneal metal foreign body removal

The purpose of the study was to examine the corneal inflammatory reaction and Langerhans cells with confocal microscopy after metal foreign body removal.

Corneal metal foreign body was removed from 9 eyes of 9 consecutive patients 12.1+/-13.6 (4 to 72) hours after superficial angle grinder injury. Both eyes were examined with the Heidelberg Retina Tomograph II (HRT II) Rostock Cornea Module. Morphology and density of epithelium, nerves, metal deposits, keratocytes, endothelium, and Langerhans cells were compared to the uninjured fellow eyes (controls).

Irregularity and partially missing superficial epithelium was found in all cases. Around the area of injury prolonged basal and wing epithelial cells were found in all eyes. The basal epithelium density is lower than in the control eye (p=0.043). Density of Langerhans cells (68.1+/-24.2/mm2) was increased in the epithelium, compared to controls (35.2+/-21.8/mm2, p=0.012). Keratocyte and endothelium densities were not different from that of controls. Some keratocytes showed signs of activation and the inhomogeneous background reflectivity revealed extracellular matrix alterations. Inflammatory reaction was observed up to260 micronm depth. The metal foreign body particles had high reflectivity and irregular edge.

In vivo confocal microscopy provided additional information to biomicroscopic signs such as epithelial damage and inflammation. It showed the effects of metal foreign bodies in the cornea: nerve damage and Langerhans cell density increase. Langerhans cells seem to play an important role in the inflammatory response after corneal foreign body injuries.