Systemic DEX increases IOP and decreases conventional outflow facility in mice. (
A) Intraocular pressure as a function of time after surgery for DEX (
filled circles) and sham-treated control mice (
open circles) averaged over all three cohorts (
P = 2 × 10
−10;
N = 31 DEX-treated and 28 sham-treated control mice at baseline;
n = 21 DEX and 28 controls at week 3). For cohorts 1 and 2, BL was taken immediately before surgery, whereas for cohort 3, BL was taken 5 to 8 days before surgery. Cohort 3 was terminated after 3 weeks and was not included in the 4-week time point.
Bars are SD. (
B) The perfusion flow rate (mean ± SD) as a function of perfusion pressure in enucleated eyes from DEX-treated (
filled circles;
n = 9) and sham-treated control mice (
open circles;
n = 11). The
trend lines represent the slope and intercept of the fitted flow rate (
Q) versus pressure (
P) relationship averaged over all perfusions for each group (excluding one outlier in the DEX-treated group). Data are from cohorts 2 and 3 only, where perfusions were done at physiological temperature and hydration. (
C) Box and whisker plots for the slope, representing conventional outflow facility (
C), and zero pressure intercept of the flow rate versus pressure relationship for DEX-treated and sham-treated control mice. The decrease in
C with DEX is statistically significant (
P = 1 × 10
−5). The zero pressure intercept is often assumed to represent the unconventional outflow rate.
Whiskers represent the range,
box edges represent the first and third quartiles, and the
centerline represents the median, excluding one outlier (
asterisk). (
D) Intraocular pressure measured immediately before death plotted as a function of conventional outflow resistance (1/
C) measured in the same mouse after enucleation for DEX-treated (
filled circles,
n = 10) and sham-treated control mice (
open circles,
n = 11) from cohorts 2 and 3. The
gray-shaded data point represents the outlier from the DEX group identified in (
C). The slope of the line of best fit is statistically significant (
P = 0.007;
R2 = 0.33, including outlier), suggesting that elevated IOP following DEX is due in large part to obstruction of the conventional outflow pathway.
Supplementary Figures S2 and S3 show IOP and
C data from each cohort separately.