Johnny Tam, Ph.D.

Stadtman Investigator

Clinical and Translational Imaging Unit


Building 10, Room 10N109,10 Center Drive,Bethesda,MD-20892-1860


Research Topics

The goal of our research is to understand the onset and progression of retinal diseases at the cellular level, using advanced optical imaging techniques such as adaptive optics. Adaptive optics is a technology for measuring and correcting the optical imperfections utilized in astronomy, microscopy, and vision science. When combined with a state-of-the-art ophthalmic imaging platform, highly detailed images of the cells in the human retina can be acquired.  The approach is to visualize healthy and diseased cells directly inside patients’ eyes to determine the sequence and timing of all the cumulative microscopic changes that give rise to clinically-significant disease phenotypes. Our research spans the development, implementation, and application of advanced optical instrumentation, as well as the acquisition, processing, and analysis of rich imaging datasets. We are particularly interested in studying the outer retina, consisting of photoreceptor neurons, retinal pigment epithelial cells, and choriocapillaris blood vessels. This multi-layered complex is not only critical for the phenomenon of vision, but also, is a useful system for modeling the in vivo interactions of neurons, epithelial cells, and vasculature within the central nervous system, in health, aging, and disease.


Dr. Tam received a bachelor’s degree in bioengineering from the University of California, San Diego, followed by a Ph.D. in bioengineering from a joint program administered by the University of California, San Francisco and the University of California, Berkeley. His graduate studies, under the mentorship of Austin Roorda, focused on developing noninvasive microvascular imaging tools to study diabetic retinopathy. He then went on to pursue postdoctoral training in the lab of Melike Lakadamyali, working on stochastic optical reconstruction microscopy (STORM), a superresolution technique. Dr. Tam was recently named a Stadtman Investigator, where he and his staff are working on clinical applications of adaptive optics.

Selected Publications

  1. Bower AJ, Liu T, Aguilera N, Li J, Liu J, Lu R, Giannini JP, Huryn LA, Dubra A, Liu Z, Hammer DX, Tam J. Integrating adaptive optics-SLO and OCT for multimodal visualization of the human retinal pigment epithelial mosaic. Biomed Opt Express. 2021;12(3):1449-1466.

  2. Jung H, Liu J, Liu T, George A, Smelkinson MG, Cohen S, Sharma R, Schwartz O, Maminishkis A, Bharti K, Cukras C, Huryn LA, Brooks BP, Fariss R, Tam J. Longitudinal adaptive optics fluorescence microscopy reveals cellular mosaicism in patients. JCI Insight. 2019;4(6).

  3. Jung H, Liu T, Liu J, Huryn LA, Tam J. Combining multimodal adaptive optics imaging and angiography improves visualization of human eyes with cellular-level resolution. Commun Biol. 2018;1:189.

  4. Liu J, Jung H, Dubra A, Tam J. Cone Photoreceptor Cell Segmentation and Diameter Measurement on Adaptive Optics Images Using Circularly Constrained Active Contour Model. Invest Ophthalmol Vis Sci. 2018;59(11):4639-4652.

  5. Liu T, Jung H, Liu J, Droettboom M, Tam J. Noninvasive near infrared autofluorescence imaging of retinal pigment epithelial cells in the human retina using adaptive optics. Biomed Opt Express. 2017;8(10):4348-4360.

This page was last updated on August 6th, 2021