To evaluate the amount of the pupillary block component in primary ang
le-closure glaucoma, the dark-room prone-position test was carried out
in 30 eyes of 20 primary angle-closure glaucoma patients, before and
one month after argon laser iridotomy. The pupillary block component i
n the prone position test (5.8+/-5.6 mmHg), which is the amount of red
uction in IOP rise in the post-laser dark-room prone-position test, co
mposed 67.8% of the IOP rise in the pre-laser dark-room prone-position
test (8.6+/-5.6 mmHg). The amount of the pupillary block component co
rrelated significantly with the IOP rise in the pre-laser dark-room pr
one-position test (r=0.880, P<0.001). The amount of the non-pupillary
block component was relatively constant and correlated poorly with the
IOP rise in the pre-laser dark-room prone-position test (r=0.163, P=0
.386). The pupillary block component was significantly larger than the
non-pupillary block component in the eyes with an IOP rise of greater
than or equal to 7 mmHg in the pre-paser dark-room prone-position tes
t (P<0.01). The dark-room prone-position test could be useful in evalu
ating the pupillary block component in angle-closure glaucoma eyes and
helpful in making a decision for laser iridotomy.