Abstract
Purpose::
To test the hypothesis that in experimental retinopathy of prematurity (ROP) retinal neovascularization (NV) and vessel tortuosity have distinct spatial and temporal links with receptor and post-receptor ion demand.
Methods::
Newborn rats were raised in either room air (controls) or variable oxygen (50% / 10%). After 14 days, 50% / 10% rats were recovered in room air until postnatal day 19 (P19) or P22. Peripheral retinal NV severity and incidence, and panretinal arteriole and venule tortuosity indexes (TIa, TIv) were measured from ADPase stained retinal flatmounts. Intraretinal ion demand and retinal thickness were measured from 23.4 µm in-plane resolution manganese-enhanced MRI (MEMRI) data collected 4 hours after MnCl2 injection i.p.
Results::
In 50% / 10% rats, peripheral retinal NV severity was significantly greater than controls at P19 and decreased by P22. Panretinal TIa and TIv were increased over control values at P19 but only TIv decreased by P22. Unlike controls retinas at P19 which had a centroperipheral total retinal thickness gradient, 50% / 10% retinas had similar central and peripheral total retinal thickness. The 50% / 10%group also demonstrated a correlation between peripheral retinal NV and TIa and TIv. Peripheral intraretinal uptake of manganese was significantly increased relative to controls at P19 and decreased by P22. Peripheral intraretinal retinal manganese uptake correlated with peripheral NV severity and panretinal TIa. In contrast, ion demand of central post-receptor, but not receptor, retina was significantly correlated with peripheral NV severity and panretinal TIa. Panretinal TIv was not correlated with intraretinal ion demand in any case.
Conclusions::
The present data are consistent with differential spatial and temporal links between supernormal layer-specific ion demand, peripheral retinal NV, and panretinal arteriole vessel tortuosity.
Keywords: retinopathy of prematurity • neovascularization • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)