Optical Coherence Tomography (OCT)

OCT is critical technology for the study and treatment of ocular disease and is already widely implemented in clinical settings. By investing in a diverse portfolio of OCT technology, the AOIP enables the broadest options possible for researching different parts of the retina and comparing the capabilities of available devices. Our lab has access to OCT and OCT Angiography systems for both human and animal-based research. Our devices include a Spectralis® OCT system from Heidelberg Engineering, two EnvisuTM Spectral Domain Ophthalmic Imaging Systems from Bioptigen, a Cirrus HD-OCT 5000 from Carl Zeiss Meditec, an Optovue OCT Angiography (OCT-A) system and a custom built OCT-A system optimized for small mammal imaging.

Our current human research focuses on examining foveal pit development across a variety of pathologies and developing a diverse normative reference database; our animal research focuses on the development of new cone-dominant animal models of inherited retinal disease. The AOIP also develops new software-based techniques for analysis of OCT images. 

Given the importance of the fovea for high acuity vision, there has been much research into foveal development and the factors affecting it, and our lab is no exception. Several inherited retinal conditions can result in partial development of the fovea and provide insight into its development, including two of our major research foci, achromatopsia and albinism. Most recently we found that despite incomplete foveal excavation, patients with achromatopsia do have a foveal avascular zone (FAZ), in contrast to people with albinism who show no FAZ.

Foveal pit and FAZ metrics vary with factors like race and age, meaning in order to accurately identify deviations from healthy retinal morphology in at-risk patients, clinicians need access to matched controls. Our lab is compiling a diverse normative database and developing accompanying software, OCTAMIND for exactly this use. Through collaborations with clinicians, we are also able to image patients with a variety of retinal pathologies, such as macular telangiectasia and diabetic retinopathy, to analyze and test against the normative database.

Animal models of retinal disease are vital for the development of new treatments; most recently they have led to breakthroughs in gene therapies for previously untreatable inherited retinal degenerations. However, most widely available rodent models have rod-based retinae, and therefore do not display phenotypes similar to humans with cone-based retinal degenerations. With funding from the NIH audacious goals grant, the AOIP and collaborators Dr. Jacque Duncan and Dr. Deepak Lamba at UCSF, Dr. Aron Geurts also at MCW, and Dr. Jay Neitz at the University of Washington are seeking to fill this gap with cone-dominant rodent models of cone-degenerative disease: the 13-lined ground squirrel and tree shrew. OCT is critical for evaluating the retinal degeneration exhibited by these new models and their similarity to human patients, given that OCT is the most widely used technique for evaluating progression of human disease. 

If you are interested to talking to one of our lab members see our People page (link) for contact information, or if you would like to collaborate please visit our Collaboration page.

OCT Reflectivity Analytics (ORA)

One method that is commonly used to analyze the different retinal layers in an OCT image is by generating a longitudinal reflectivity profile (LRP). An LRP is a plot of the reflectivity (a.u.) across a distance given in pixel height or microns. (Insert image of an OCT and the corresponding LRP) The peaks seen in an LRP are associated with different retinal layers and valuable information can be gained by measuring the distance between different peaks and observing differences in reflectivity between layers. Comparing the distance between the peaks of different layers can give researchers information of the thickness or length of different retinal features in vivo, which can in turn help provide information on the cone photoreceptor structure within said layers. For example, measuring the outer nuclear layer (ONL) thickness in subjects with achromatopsia, an inherited cone dysfunction syndrome, can provide researchers with insight on the remnant cone structure which is an important prerequisite for therapeutic success using gene therapy. 

OCT Reflectivity Analytics (ORA) is a tool which was designed to allow users to analyze OCT images in a consistent and reproducible manner by producing LRPs. A user can input an OCT B-scan, enter in the axial and transverse scale information in µm per pixel, manually select an anchor point (generally the fovea) or use the automated foveal finding option, select analysis parameters, and ORA will automatically generate the desired LRPs. Once the LRPs are generated the user can then label the peaks with the name of the corresponding retinal layer and export the analysis for further interpretation in MATLAB. 

If you are interested in talking to one of our lab members joining us see our People page for contact information, or if you would like to collaborate, please visit our Collaborate page.