Long-term observations of proton-irradiated monkey eyes
E. S. Gragoudas, N. Z. Zakov, D. M. Albert and I. J. Constable
Fifteen owl monkeys (30 eyes) that received proton irradiation of discrete
areas of the retina and choroid have been observed for 3 1/2 years or more
after irradiation. The dose delivered to the retina varied from a single
dose of 1,600 to 4,750 proton rads and from 10,250 to 18,250 rads delivered
in five fractions over a period of one month. Fundus examination,
fluorescein angiography, and light and electron microscopy revealed
chorioretinal changes at the area of irradiation. The part of the retina
adjacent to the chorioretinal scar showed preservation of normal retinal
vascular architecture on trypsin digest studies of the retina and on
electron microscopic examination, even 1 mm from the edge of the scar. The
results of this study suggest that proton beam irradiation may markedly
reduce delayed ocular complications, especially radiation retinopathy,
which is common to other forms of radiotherapy in the treatment of
intraocular tumors.
