se (l) a
he high-
the low-
"acaptn -ietrle
17
nticular
ed than
ferences
2 higher
out (see
the lens
e argues
me post
retween
aee er
lens exrwn the
gm ee te
Aerriam
‘nificant
obvious
wing the
retween
an ap-
nonexposed animals (increasing with age) but have
been found in significantly greater numbers in
mice exposed to even very low doses of radiation.?°
ividuals
Methods
lens will
adiation
Slit-lamp microscopic examination after iris
dilatation with tropicamide 0.5% (Mydriacyl) was
made of people within the several exposure groups
as follows: 175 rads (midline gammadoseinair),
may be
g an in-
ate), (2)
1 (3) the
ion. For
‘latively
nination
���ourse of
an adevering a
ividuals
bers (for
€ groups
L this ex-
status of
ige, and
in these
15 years
ul survey
discrete
capsular
t can be
nin the
ich may
igle lens
resent in
Figure 17. Photographsof the optic lens taken through
the slit-lamp microscope at 312 magnification and en-
larged 24% x. Lensflecks are visible in and to the right of
the light arc which lies at the left in each photograph,
created by impingementof the lamp beam onthe 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.
41 persons; 70 rads, 10 persons; 14 rads, 15 per-
sons; nonexposed, 80 persons. The observer was
unaware of the group to which each individual belonged until after the examinations, First a brief
general inspection (at a magnification of 200 or
312) was madeof the cornea, aqueous humor,
lens, and anterior vitreous humor. Representative
photographsweretaken, usually at 312 x. Finally
counts were made of minute discrete opacities
(flecks) falling within the 2.5-mm-diametercircle
projected into the viewedfield by an ocular reticle.
Counts were madewithin the anterior andposterior
subcapsularregions ofeachlens at a location about
one-half lens radius below the midline. This location was selected to minimize the corneallight reflex as the narrowslit-lamp beam was sweptacross
the counting region. Axial traverse of the focus
during counting gave depth to the counting area,
effectively creating a cylinder of 2.5-mm diameter
and extending between the lens capsule and lens
nucleus.
Eight egos were unsatisfactory because
of advanced a
comeal defects.
cataracts, lens extractions, or
SogazZ 74
. Figure 18. Electron micrograph ofoptic lens fibers of a
21-week-old mouse exposed to 3000 rads of Co gamma
rays at 6 weeks of age. Thefibers are seen in cross section,
and a defective fiber lies near the centerof thefield. (From
H.A. Johnson, Acta Iberica Radtol. Cancerol, 19: 247-54,
1964).