To relate changes in SC lumen area observed by OCT with traditional functional measures, we examined effects of pilocarpine on conventional outflow facility and IOP in two cohorts of living mice.
Figure 7 shows the pressure-flow relationship of paired mouse eyes, one treated topically with PBS and the contralateral eye treated topically with 1% pilocarpine. The anterior chambers of eyes were cannulated and subjected to three pressure steps (17, 24, and 34 mm Hg), and flow was measured at each pressure. Data show that flow was incrementally greater at 24 and 34 mm Hg compared with control. Linear regression analysis of data in
Figure 7A shows that outflow facility in pilocarpine-treated eyes was significantly different from controls, increasing by approximately 3-fold (
Fig. 7B,
P = 0.038). Interestingly, the
y-intercept (estimated flow at zero pressure) of control versus pilocarpine treatment in
Figure 7A is significantly different (0.0791 ± 0.082 vs. −0.1062 ± 0.058 μL/min,
P = 0.02). Consistent with the outflow facility increase, we observed in
Figure 7C that IOP was lower in pilocarpine-treated eyes compared with controls. Using rebound tonometry, we observed that IOP in pilocarpine-treated eyes was statistically lower 20 minutes after treatment (16.46 ± 2.23 vs. 11.08 ± 2.28 mm Hg,
P = 0.027), reaching maximum effects at 40 minutes after treatment (9.17 ± 1.91 mm Hg,
P = 0.029). Intraocular pressure began to return to normal levels at 120 minutes, reaching baseline levels by 210 minutes. By comparison, we were able to detect changes in outflow by 20 minutes, which were maintained for the duration of the experiment (∼90 minutes).