To uncover risk factors for the highly variable individual rates of progression in
cases of untreated normal-tension glaucoma.
Visual field data were assembled from 160 subjects (160 eyes) enrolled in the collaborative
normal-tension glaucoma study during intervals in which the eye under study was not
receiving intraocular pressure-lowering treatment during prerandomization and postrandomization
intervals. Analyses included multivariate analysis of time-dependent Cox proportional
hazard, Kaplan-Meier analysis of "survival" without an increment of visual field worsening,
and comparison of slopes of change in mean deviation global index over time.
Most migraine occurred in women, but analysis demonstrated that gender and presence
of migraine contribute separately to the overall risk. The risk ratio for migraine,
adjusted for the other variables was 2.58 (P =.0058), for disk hemorrhage was 2.72
(P =.0036), and for female gender 1.85 (P =.0622). The average fall in the mean deviation
index was faster in nonmigrainous women than in nonmigrainous men (P =.05). Suggesting
genetic influence, Asians had a slower rate of progression (P =.005), and the few
black patients enrolled had a tendency for faster progression. However, self-declared
history of family with glaucoma or treated for glaucoma did not affect the rate of
progression. Neither age nor the untreated level of intraocular pressure affected
the rate of untreated disease progression, despite their known influence on prevalence.
Whereas risk factors for prevalence help select populations within which to screen
for glaucoma, the factors that affect the rate of progression help decide the expected
prognosis of the individual's untreated disease and thereby the frequency of follow-up
and aggressiveness of the therapy to be undertaken.