Oxygen metabolism lies at the heart of retinal health and disease, influencing the pathophysiology of diabetic retinopathy, glaucoma, and age-related macular degeneration (AMD). However, measuring oxygen dynamics in vivo — especially at the capillary level — has remained an enduring challenge.
In a recent Neurophotonics publication, researchers from the University of Pennsylvania and John Hopkins University, Maryland, detail a multimodal imaging platform combining visible light optical coherence tomography (VIS-OCT) with phosphorescence lifetime ophthalmoscopy (PLIM-SLO) that simultaneously captures retinal microstructure and microvascular oxygen tension (pO₂) in the living mouse eye.
The system integrates two advanced optical modalities along a shared imaging path. VIS-OCT delivers ultrahigh-resolution volumetric images of retinal microanatomy and blood flow, while PLIM-SLO quantifies intravascular oxygen tension using a phosphorescent dye (Oxyphor 2P) that changes lifetime with oxygen concentration.
The team engineered a synchronized imaging protocol that allows both channels to operate simultaneously without optical interference. Using a tunable lens, the focal plane can be shifted through different retinal depths, enabling three-dimensional oxygen mapping from the superficial to deep capillary plexuses. This design permits capillary-level pO₂ measurement alongside structural imaging of vessels and neural layers.
In vivo experiments on C57BL/6 mice revealed rich structural and functional data. VIS-OCT resolved retinal layers down to Bruch’s membrane, while PLIM-SLO produced precise, depth-dependent oxygen maps. At baseline, higher pO₂ values were seen in arterioles and superficial capillaries, with gradual decreases through venules and deeper layers — patterns consistent with established retinal physiology.
When systemic oxygen was varied experimentally, PLIM-SLO detected real-time, graded changes in capillary oxygen tension, correlating closely with pulse oximetry readings. The derived oxygen–hemoglobin dissociation curves mirrored those known in murine models, validating the technique’s quantitative accuracy. Importantly, the system’s calibration accounted for visible light excitation effects from the OCT beam, ensuring precise lifetime correction.
By integrating structural and functional data, this multimodal approach provides an unprecedented view of retinal oxygen metabolism. The simultaneous imaging capability ensures spatial and temporal registration between pO₂ and anatomical features — crucial for studying microvascular regulation, disease progression, and therapeutic effects.
The study authors emphasize potential applications in retinal disease modeling and drug development, particularly for conditions characterized by hypoxia or vascular dysregulation. Future iterations incorporating Doppler flow measurements could enable full quantification of oxygen extraction and consumption in the retina, providing a metabolic fingerprint of ocular health. For ophthalmologists and vision scientists, the platform could offer a powerful experimental tool to unravel how retinal oxygen dynamics underpin both normal physiology and disease mechanisms.
In a recent Neurophotonics publication, researchers from the University of Pennsylvania and John Hopkins University, Maryland, detail a multimodal imaging platform combining visible light optical coherence tomography (VIS-OCT) with phosphorescence lifetime ophthalmoscopy (PLIM-SLO) that simultaneously captures retinal microstructure and microvascular oxygen tension (pO₂) in the living mouse eye.
The system integrates two advanced optical modalities along a shared imaging path. VIS-OCT delivers ultrahigh-resolution volumetric images of retinal microanatomy and blood flow, while PLIM-SLO quantifies intravascular oxygen tension using a phosphorescent dye (Oxyphor 2P) that changes lifetime with oxygen concentration.
The team engineered a synchronized imaging protocol that allows both channels to operate simultaneously without optical interference. Using a tunable lens, the focal plane can be shifted through different retinal depths, enabling three-dimensional oxygen mapping from the superficial to deep capillary plexuses. This design permits capillary-level pO₂ measurement alongside structural imaging of vessels and neural layers.
In vivo experiments on C57BL/6 mice revealed rich structural and functional data. VIS-OCT resolved retinal layers down to Bruch’s membrane, while PLIM-SLO produced precise, depth-dependent oxygen maps. At baseline, higher pO₂ values were seen in arterioles and superficial capillaries, with gradual decreases through venules and deeper layers — patterns consistent with established retinal physiology.
When systemic oxygen was varied experimentally, PLIM-SLO detected real-time, graded changes in capillary oxygen tension, correlating closely with pulse oximetry readings. The derived oxygen–hemoglobin dissociation curves mirrored those known in murine models, validating the technique’s quantitative accuracy. Importantly, the system’s calibration accounted for visible light excitation effects from the OCT beam, ensuring precise lifetime correction.
By integrating structural and functional data, this multimodal approach provides an unprecedented view of retinal oxygen metabolism. The simultaneous imaging capability ensures spatial and temporal registration between pO₂ and anatomical features — crucial for studying microvascular regulation, disease progression, and therapeutic effects.
The study authors emphasize potential applications in retinal disease modeling and drug development, particularly for conditions characterized by hypoxia or vascular dysregulation. Future iterations incorporating Doppler flow measurements could enable full quantification of oxygen extraction and consumption in the retina, providing a metabolic fingerprint of ocular health. For ophthalmologists and vision scientists, the platform could offer a powerful experimental tool to unravel how retinal oxygen dynamics underpin both normal physiology and disease mechanisms.
