Non-penetrating corneal foreign body injuries: relationships between distributions of corneal foreign bodies and their entering directions into the cornea
The purpose of this study was to investigate how foreign bodies enter into the cornea relative to the directions of entrance and to suggest proper protection of the eyes from foreign bodies. Seventy-eight eyes of 78 patients were classified into two groups according to the entering direction of the foreign body: certain and uncertain directions. The real distributions of foreign bodies in the cornea were obtained using photographs of the treated eyes and these were compared with theoretical distributions which were calculated based upon the theory of probability. The group with foreign bodies entering from uncertain directions comprised 16 (20%) of the 78 eyes. In this group, all the foreign bodies were made of iron, and none of them were in the upper half of the cornea. These distributions were significantly different from those in the group with foreign bodies entering from a certain direction. The theoretical probabilities of foreign bodies hitting the lower half increased, as the entering directions decreased. When foreign bodies entered into the cornea from uncertain directions, it is highly possible that they did so from lower directions. This suggests that ordinary glasses can protect the eyes from corneal foreign bodies as an eye protective tool in almost all such cases, although they are open on the temporal and upper sides.
