17
nonexposed animals (increasing with age) but have
been found in significantly greater numbers in
mice exposed to even very low doses of radiation.?°
*
Methods
Slit-lamp microscopic examination after iris
dilatation with tropicamide 0.5% (Mydriacyl) was
made of people within the several exposure groups
Figure 17. Photographs ofthe optic lens taken through
the slit-lamp microscope at 312 magnification and enlarged 24 x. Lens flecks are visible in and to theright of
the lighesarc which lies at the left in each photograph,
created by impingement of the lamp beam on the lens
posterior capsule. Left: Mouse, nonirradiated, one year
old. Right: Human,a 39-year-old Marshall Island female
exposed to 175 rads offallout radiation 15 years previously.
as follows: 175 rads (midline gammadose im air),
41 persons; 70 rads, 10 persons; 14 rads, 15 per-
sons; nonexposed, 80 persons. The observer was
unawareof the group to which each individual belonged until after the examinations. First a brief
general inspection (at a magnification of 200 or
312 x) was made of the cornea, aqueous humor,
lens, and anterior vitreous humor. Representative
photographswere taken, usu....v at 312 x. Finally
counts were made of minute discrete opacities
(flecks) falling, wi
.2,5-mm-diantetey’circle
projected into the viewed
aSeidbyatt ocular
Counts weremade withirr
vor andy
subcapsular:regions ofcaeheder
| locationabout
one--half lenetedius pel ova midline. Thisloca-
tion was selec
‘Fhintitae the-cgeneal light reflex as the nagpyait-lamp beam was swept adibss
the counting. region, “Axial traverse of the focus
duringcounti
gave dapth to the couritifigarea,
effectively creating‘acylinders of25-mm diameter
and extending betweenthe lenscapsule and léns
nucleus.
-
74S
OF
Eight examinationswetbunsatistactéry betause
be
of advanced age cataracts, lens extractions, or
corneal defects.
we
he
os.
Figure 18. Electran micrograph of optic lens fibers of a
21-week-old mouse exposed to 3000 rads of Co gamma
rays at 6 weeks of age. The fibers are seen in cross section,
and a defective fiber lies near the centerof the field. (From
H.A. Johnson, Acta Iberica Radtol. Cancerol. 19: 247-54,
1964).