Microscope-Integrated Optical Coherence Tomography

Ophthalmic surgery is largely performed using microscopes that leave much to be desired in the realm of stereoscopy. The standard en face view often leaves surgeons to rely on non-visual cues to perform micro-scale tasks. Optical coherence tomogrophy (OCT) allows for the visualization of the miniscule structures being operated on in 3D. Current OCT systems can take single images in 3D or real time images in 2D, but can not take real time images in 3D. An OCT imaging modality that is able to take micron-scale real time images in 3D would be useful for ophthalmic surgery feedback and guidance.

The Biophotonics Group I am a part of has been developing an OCT system for just this - real-time 3D image-guided ophthalmic surgery. The previous integration of the system, while effective, was large and was a hindrance to normal movement around the patient by surgeons and assistants. I was responsible for taking a new compressed optical layout and mechanically integrating it into the currently used surgical microscopes.

One of the great challenges in this project was navigating the intersecting spheres of demands of the surgeons, the restrictions of the optical layout, and the lack of accurate CAD representation of the microscope. Guided questioning and discussion helped me decipher the complex maneuvers of the surgeon and her assistants so I could distill them into actionable design goals. In short, the need was for the new scanhead to be as out of the way as possible since it had to be placed in such a high traffic area, i.e. a space where tools and instruments are passed or in the patient's body habitus.

The manufacturer of the surgical microscopes we were integrating the scanhead with was not eager to distribute engineering drawings of their designs, let alone CAD files. To work around this, I imagined splitting the miscroscope up into layers in the Z dimension as I do in my mind when I am working in CAD. To represent each layer physically, I cut and taped posterboard until I had "negatives" of each layer of the microscope. From these, and information on layer spacing, I could rebuild the scope in SolidWorks and more confidently build around it, bringing the optics up and out of the way with less guess work.

Related Publications

Carrasco-Zevallos, O., Keller, B., Viehland, C., Shen, L., Waterman, G., Chukwurah, C., . . . Izatt, J. A. (2015). Real-time 4D Stereoscopic Visualization of Human Ophthalmic Surgery with Swept-Source Microscope Integrated Optical Coherence Tomography. Paper presented at the Investigative Ophthalmology & Visual Science.
Carrasco-Zevallos, O., Keller, B., Viehland, C., Shen, L., Waterman, G., Todorich, B., . . . Kuo, A. (2016). Live volumetric (4D) visualization and guidance of in vivo human ophthalmic microsurgery with intra-operative optical coherence tomography. Scientific Reports, 6, 31689.
Mehta, R., Nankivil, D., Zielinski, D. J., Waterman, G., Keller, B., Adari, P., . . . Kuo, A. N. (2016). Remote, web-based interface control of handheld swept source OCT system for acute care settings. Paper presented at the Investigative Ophthalmology & Visual Science.
Shen, L., Carrasco-Zevallos, O., Keller, B., Viehland, C., Waterman, G., Desouza, P., . . . Izatt, J. A. (2015). Novel microscope-integrated stereoscopic display for intrasurgical optical coherence tomography. Paper presented at the SPIE BiOS.
Shen, L., Carrasco-Zevallos, O., Keller, B., Viehland, C., Waterman, G., Hahn, P., . . . Izatt, J. A. (2015). Novel Microscope-Integrated Stereoscopic Heads-up Display for Intrasurgical OCT in Ophthalmic Surgery. Paper presented at the Investigative Ophthalmology & Visual Science.
Shen, L., Carrasco-Zevallos, O., Keller, B., Viehland, C., Waterman, G., Hahn, P. S., . . . Izatt, J. A. (2016). Novel microscope-integrated stereoscopic heads-up display for intrasurgical optical coherence tomography. Biomedical optics express, 7(5), 1711-1726.
Shen, L., Keller, B., Carrasco-Zevallos, O., Viehland, C., Bhullar, P. K., Waterman, G., . . . Izatt, J. A. (2016). Oculus Rift® as a Head Tracking, Stereoscopic Head Mounted Display for Intra-Operative OCT in Ophthalmic Surgery. Paper presented at the Investigative Ophthalmology & Visual Science.