Abstract
Purpose :
ATP-sensitive potassium (KATP) channel openers (e.g., diazoxide) are known to increase blood flow in various non-ocular organ systems through vasodilation. KATP channel openers can also lower IOP, presumably by increasing aqueous humor outflow through the episcleral venous system. To determine if diazoxide could influence the retina vasculature, we evaluated retinal vessel diameter (RVD) in vivo.
Methods :
RVD was measured by fluorescein angiography. Fundus images of retina from C57BL/6J mice treated intravitreally (single treatment, n=5) or topically once daily for 7 consecutive days (n=5) with diazoxide (5 mM) or vehicle, were captured by Phoenix Micron IV OCT. Predetermined retinal vessels were each measured at three separate locations in all retinas and averaged to obtain mean vessel diameter per retina. Imaging was performed in anesthetized mice at 15 min post treatment for intravitreal group and at 1 h and 23 h after the last topical treatment (day 7). Post treatment RVD was measured at 7 days after termination of diazoxide treatment in the topically-applied group.
Results :
RVD increased by 30.0 ± 7.1% (n=5, p<0.001) from baseline, within 15 minutes of intravitreal diazoxide injection, while injection with vehicle caused no significant change (-4.1 ± 4.0%, n=5, p=0.07). When diazoxide was applied topically once daily for 7 days, RVD at 1 h after day 7 treatment was 20.0 ± 10.7% (n=5, p=0.007) greater than baseline values, with no change observed in vehicle treated eyes (-0.4 ± 3.2%, n=5, p=0.84). At 23 h after the Day 7 dose, RVD was 19.0 ± 5.2% (n=5, p<0.001) greater than baseline values with no significant change in the vehicle treated eyes (1.7 ± 1.6 %, n=5, p=0.07). Seven days following the last topical treatment, RVD returned to baseline levels (1.7 ± 3.5%, n=2, p=0.66).
Conclusions :
Treatment with diazoxide causes dilation of retinal vessels and may influence blood flow to this region. This may have beneficial effects for some retinal pathologies.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.