Beta-human chorionic gonadotropin, progesterone, and aqueous dynamics during pregnancy
N. Ziai, S. J. Ory, A. R. Khan and R. F. Brubaker
Department of Ophthalmology, Mayo Clinic, Rochester, Minn.
OBJECTIVE: To determine whether the altered hormonal milieu of pregnancy is
associated with changes in the dynamics of aqueous humor formation and
drainage. DESIGN: Nineteen women were studied during each trimester of a
single pregnancy and post partum. Measures of aqueous dynamics included
intraocular pressure, aqueous flow, facility of outflow, aqueous flare, and
corneal thickness. RESULTS: Pregnancy was associated with relatively lower
intraocular pressure, reduced aqueous flare, increased corneal thickness,
and increased aqueous outflow facility. Aqueous flow was unchanged. The
progesterone level increased during pregnancy and decreased during the
postpartum period. The beta-human chorionic gonadotropin level was highest
during the first trimester. The progesterone level, but not the beta-human
chorionic gonadotropin level, was correlated with intraocular pressure,
aqueous flare, and corneal thickness. The change in aqueous outflow
facility that accompanied pregnancy could not be correlated directly to
changes in beta-human chorionic gonadotropin or progesterone
concentrations. CONCLUSIONS: Aqueous flow remains constant during and after
pregnancy, but intraocular pressure decreases during pregnancy due to an
increase in the outflow facility. The changes in aqueous dynamics are
consistent with the hypothesis that excess progesterone during pregnancy
blocks the ocular hypertensive effect of endogenous corticosteroids.
However, we were unable to find a statistically significant correlation
when a direct comparison between the observed changes in outflow facility
and the observed changes in the progesterone level was made, perhaps
because of intersubject variability of these changes. The changes in
intraocular pressure and outflow facility could have been due to one of
many other changes in pregnancy that were not measured.
