Photoacoustic properties of anterior ocular tissues

• Type of Material: Article
• Authors: Kelsey P Kubelick, Georgia Institute of Technology; Eric J Snider, Georgia Institute of Technology; Christopher Ethier, Emory University; Stanislav Emelianov, Emory University
• Language: English
• Date: 2019-05-01
• Publisher: Society of Photo-optical Instrumentation Engineers, International Biomedical Optics Societ
• Publication Version: Final Published Version
• Copyright Statement: © The Authors.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1117/1.JBO.24.5.056004
• Title of Journal or Parent Work: Journal of Biomedical Optics
• Volume: 24
• Issue: 5
• Start Page: 1
• End Page: 11
• Grant/Funding Information: The authors acknowledge support from the Georgia Research Alliance (GRA) and the National Science Foundation (NSF).
• Keywords: ULTRASOUND BIOMICROSCOPY; Optics; CELLS; OPTICAL COHERENCE TOMOGRAPHY; INTERNAL ABSORPTION-COEFFICIENT; THRESHOLD; ORGAN-CULTURE; MODEL; Radiology, Nuclear Medicine & Medical Imaging; SWEPT SOURCE; spectroscopic imaging; stem cell tracking; anterior segment; ophthalmology; Science & Technology; photoacoustic imaging; Physical Sciences; COLOR; Biochemical Research Methods; ultrasound imaging; Life Sciences & Biomedicine; Biochemistry & Molecular Biology; SEGMENT
• Research Categories: Physics, Optics; Health Sciences, Opthamology; Engineering, Biomedical

Abstract

Clinical imaging techniques for the anterior segment of the eye provide excellent anatomical information, but molecular imaging techniques are lacking. Molecular photoacoustic imaging is one option to address this need, but implementation requires use of contrast agents to distinguish molecular targets from background photoacoustic signals. Contrast agents are typically selected based on a priori knowledge of photoacoustic properties of tissues. However, photoacoustic properties of anterior ocular tissues have not been studied yet. Herein, anterior segment anatomy and corresponding photoacoustic signals were analyzed in brown and blue porcine eyes ex vivo. Measured photoacoustic spectra were compared to known optical absorption spectra of endogenous chromophores. In general, experimentally measured photoacoustic spectra matched expectations based on absorption spectra of endogenous chromophores reported in the literature, and similar photoacoustic spectra were observed in blue and brown porcine eyes. However, unique light-tissue interactions at the iris modified photoacoustic signals from melanin. Finally, we demonstrated how the measured PA spectra established herein can be used for one application of molecular PA imaging, detecting photoacoustically labeled stem cells in the anterior segment for glaucoma treatment.