Effects of fast neutrons on the eye.

The study of 93 eyes receiving neutron irradiation establishes the character of the ophthalmic complications of neutron. Significant changes are produced in the eyelids, conjunctiva, and cornea, but the production of cataract is relatively unimportant. No reaction was seen after neutron treatment that had not already been seen after chi or gamma radiation. That the unavoidable damage is similar to that reported with other forms of radiation, and not worse, is an important finding in view of the statistically significant benefit of neutron treatment to patients in a controlled clinical trial of advanced tumours of the head and neck (Catterall and others, 1975). The observations indicate that the improved cure rates with neutrons are not obtained at the expense of inflicting greater damage to normal structures. This investigation has also shown that the neutron effects of treating these very extensive tumours are acceptable and that, with carefully measured doses, they are predictable. The dose-response relationship in categories of clinical effect for a smaller series of patients, reported in Table 1 of our preliminary communication (Brown and other, 1976), is confirmed.