Tissue Oxygenation in Small Retinal Vessels

Summary Recentlywe found extensive remodeling of the microvasculature of the retinaoccurring in some diabetic patients much earlier than expectedThis provides the potential for novel biomarkers to improve classification of patients for management and cost effective testing of therapiesHoweverthe equipment is too expensive for most clinics and small practicesThese early retinal microvascular changes cannot be seen with routine clinical examination or traditional imaging devicesWe propose to reduce the cost and improve ease of use of this technology to allow widespread detection of retinal microvascular changes as biomarkersPart of the high cost of these devices is the adaptive opticsAOsubsystemwhich includes one or more deformable mirrors to compensate for the aberrations of the optics of the human eyeThe contrast of retinal images is further improved by scanning the illumination and using confocal detection aperturesBy designing a simpler AO imager with only sufficient resolution to provide improved visibility of small vessel lesionsa wider field of viewmore compact layoutand greater ease of use can be realized with less challenging optical performance parametersTo provide a clinically useful tool for examination of the retinal microvascular lesions in diabetes and other retinal vascular diseasesalong with improving information about oxygen in the retinawe proposeAimsIn Aimwe will optimize adaptive optics digital light ophthalmoscopeAO DLOfor high contrastpseudo color video imaging of the human retina at high magnification to improve detection of microvascular lesions and quantification of the relative absorption of arterioles and venulesThedeg AO field of view on a high contrast NIR wide field image will ease the burden of localizing features or montaging AO images taken sequentiallywith an acceptable trade off in maximum imaging resolutionThe AO DLO will acquire monochrome images ofcontrolsusing alternating red and yellow LED illumination wavelengths that match those used in oximetryThis provides high contrast pseudo color retinal imaginggood retinal penetration for dark eyesand strong absorption signals from blood bandsIn Aimwe will use the AO DLO to image the retinal microvasculature incontrols anddiabetic patients with less than severe non proliferative retinopathyWe will perform parametric studies of aperture size and positionand focal planeto optimize the reproducibility of the measurements of the relative absorption invisible wavelength bands in with the AODLOThese manipulationsalong with an exercise regimewill provide information about oxygen extraction in arterioles and venules for capillary networksIn Aimwe will image the same subjects with the high resolution Indiana AO SLOBurnsexamining vessel walls and lumenthen re assess placement of oximetry data samples and recompute optical density ratiosThis project offers the potential to move high quality adaptive optics retinal imaging into use with more patientsimproving the classification of diabetic eyes for management and evaluating therapies Project Narrative Recentlywe found extensive remodeling of the microvasculature of the retinaoccurring in some patients much earlier than expectedThese novel biomarkers are seen in diabetic retinas using adaptive optics equipment that is too expensive for most clinics and small practicesproviding a barrier for use in typical clinical examinationWe propose to reduce the cost and improve ease of use of this technology to allow widespread detection of microvascular changes and quantification of retinal oxygen as biomarkers