Zhang Lab

The retina is the only portion of the central nervous system (CNS) that can be studied non-invasively through the unique optical window of the eye. In principle, the neural, glial, and vascular tissue in the retina of a living human subject can be observed at the histologic level. Retinal imaging has thus been a primary diagnostic modality for retinal disease and plays a critical role in the clinical management of systemic and CNS diseases. Advanced Ophthalmic Imaging Laboratory (AOIL) research focuses on developing advanced ophthalmoscopy, with an emphasis on adaptive optics (AO) imaging, to facilitate in vivo study of chorioretinal disease and systemic disease at the cellular and sub-cellular level.

In the AOIL, we have developed state-of-art high-resolution retinal imaging instruments that integrate adaptive optics (AO), scanning laser ophthalmoscopy (SLO), and optical coherence tomography (OCT). SLO and OCT represent two modern revolutionary imaging mechanisms that reveal the 3-D retinal structure in the living eye. AO is a technique that can compensate for the eye’s optical defects, thereby enabling SLO and OCT with (near) diffraction-limited resolution. The AOIL AO-SLO-OCT has imaged cone and rod photoreceptors in the living human retina. Another imaging instrument that was recently built in the AOIL is a high-speed adaptive optics near-confocal scanning ophthalmoscope (AONCO). This device can image the human retina with a frame rate of up to 800 Hz, representing the fastest en-face imaging instrument for the living human eye in the world to date. High-speed high resolution imaging enables direct and accurate measurement of the movement of individual erythrocytes and leukocytes flowing in human retinal capillaries without using any exogenous contrast agents, opening a new horizon for studying high-order retinal hemodynamics that reflect the mechanical property of retina capillaries. In addition, a new generation of technology is being developed for in vivo imaging of the retina at the molecular level.

We are looking forward to gaining the ability to unveil the molecular signatures of retinal health by objective characterization of the compounds in the retina and its supportive retinal pigment epithelium (RPE), which are associated with retinal metabolism and implicated in the process of aging and the pathogenesis of various retinal diseases.

The long-term goal of AOIL is to develop technological advancements that improve the understanding and treatment of diseases that blind the human eye and affect the central nervous system. With research grants from the National Institute of Health, the National Sciences Foundation, the EyeSight Foundation of Alabama, the International Retinal Research Foundation, and the Keck Foundation, the AOIL AO-SLO-OCT has been employed for in vivo investigation of age-related macular degeneration, a leading causing of central vision loss in more than 10 million older Americans. Advance AO enhanced retinal imaging provides important avenues to study various common medical and neurologic conditions such as hypertension, diabetes, and Alzheimer’s disease.