Visual Function Responses of Patients Receiving X- or ⁶⁰Co Gamma-radiation Therapy in the Region of Head and Neck

Summary

Visual function response of patients receiving fractionated therapeutic radiation treatments in the region of head and neck were measured before and after irradiation. The total cumulative exposures were divided into four categories: (a) low-dose group (100–1000 rads), (b) a low-medium-dose group (1000–2500 rads), (c) medium-dose group (2500–4500 rads), and (d) high-dose group (4500–7000 rads or more). Clinical examination of the eyes, followed by retinal function tests such as electroretinography (ERG), dark adaptation tests and retinal profiles, was done at various intervals before, during and after radiation therapy. In general, with the low-dose and low-medium-dose groups there were no significant changes in the amplitudes of the electroretinographic wave components, but the adaptation thresholds increased. In the medium-dose group, the amplitudes of a and b waves decreased to 50 per cent of the original value, and the light and dark adaptation thresholds increased. In the high-dose group the amplitudes of ERG wave components were reduced to less than 10 per cent of the original value or the ERG was completely extinguished. In some cases, vision was restricted to recognition of hand movements.