Abstract
Purpose :
Intracameral injections are an effective delivery method to conventional outflow tract tissues. However, with this technique there is a subsequent inflammatory response of unknown duration. Here we assess the inflammatory response following transcorneal needle puncture with respect to macrophage density within the conventional outflow tract for up 14 days. We also monitor intraocular pressure (IOP), outflow facility and distal vessel diameters after transcorneal puncture.
Methods :
C57Bl/6 mice, aged 3-5 months, received full thickness transcorneal punctures using beveled glass microneedles, while the contralateral eyes served as controls. Baseline IOPs were taken prior to puncture. Following treatment, IOP was measured at 1 day, 3 days, 6-8 days, and 14 days in puncture and control eyes. One cohort of mice were subjected to ex vivo perfusions 1 day after puncture to measure trabecular resistance. At 3 days, 7 days and 14 days following puncture, eyes were enucleated, fixed, immunostained, and imaged using confocal microscopy. Macrophage density and distal vessel diameters were measured using 6 nonconsecutive z-stack confocal images. Statistical analysis was performed by one-way ANOVA and post hoc t-tests with p < 0.05 considered significant.
Results :
After 1-day post-puncture, there was a significant reduction in IOP (n=17; p<0.0001) whereas there was no change in facility (trabecular resistance) (n=8; p=0.55). Distal vessel diameters of arterioles, venules, and capillaries were enlarged (p<0.02) with puncture at 1-day post-treatment. Macrophage density was significantly increased in the trabecular meshwork/Schlemm’s Canal region at day 3, day 7 and day 14, but not day 1 following puncture (p<0.0001, p<0.0001, p<0.002, p=0.0630, respectively). Macrophage density was significantly increased around distal vessels at days 1 and 3 (p<0.0005 and p<0.02), but not at days 7 or 14 (p=0.25 and p=0.54).
Conclusions :
Full thickness transcorneal needle puncture induces an inflammatory response by recruiting macrophages to the conventional outflow tract which can last for up to 14 days. IOP is reduced but facility is not changed in punctured eyes at day 1. Future studies are needed to further characterize distal vessel changes.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.