In Vivo Retinal Vascular Oxygen Tension Imaging and Fluorescein Angiography in the Mouse Model of Oxygen-induced Retinopathy

Purpose: Oxygenation abnormalities are implicated in the development of retinopathy of prematurity (ROP). The purpose of this study is to report in vivo retinal vascular oxygen tension (PO2) measurements and fluorescein angiography (FA) findings in the mouse model of oxygen-induced retinopathy (OIR).

Methods: We exposed 19 neonatal mice to 77% oxygen from postnatal day 7 (P7) to P12 (OIR), while 11 neonatal mice were kept under room air (control). Using phosphorescence lifetime imaging, retinal vascular PO2 was measured followed by FA. Repeated measures ANOVA was performed to determine the effects of blood vessel type (artery and vein) and group (OIR and control) on PO2. Avascular retinal areas were measured from FA images in OIR mice.

Results: There was a significant effect of vessel type on PO2 (P < 0.001). The effect of group on PO2 was not significant (P = 0.3), indicating similar PO2 between OIR and control mice. The interaction between group and vessel type was significant (P = 0.03), indicating a larger arteriovenous PO2 difference in OIR mice than control mice. In control mice, FA displayed normal vascularization, while FA of OIR mice showed abnormalities, including dilation and tortuosity of major retinal blood vessels, and avascular regions. In OIR mice, the mean percent avascular retinal area was 33% ± 18%.

Conclusions: In vivo assessment of retinal vascular oxygen tension and vascularization patterns demonstrated abnormalities in the mouse model of OIR. This approach has the potential to improve understanding of retinal vascular development and oxygenation alterations due to ROP and other ischemic retinal diseases.