9 July 2001 Using optical coherence tomography to elucidate the impact of fixation on retinal laser pathology
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Proceedings Volume 4257, Laser-Tissue Interaction XII: Photochemical, Photothermal, and Photomechanical; (2001) https://doi.org/10.1117/12.434698
Event: BiOS 2001 The International Symposium on Biomedical Optics, 2001, San Jose, CA, United States
Purpose: The direct comparison of in-vivo OCT images with fixed tissues sections assumes the fixation of tissue has no effect on the size and configuration of final pathology images such as light micrographs. Fixation artifact has been a concern in numerous studies of the pathology of retinal laser lesions. We tested this hypothesis. Methods: The Humphrey OCT model 2000 with a custom mirror and lens assembly was used to scan tissue phantoms and both fresh and fixed ex-vivum tissue samples. The optical configuration was determined by optimization of the contrast and signal strength on tissue phantoms. Fresh porcine retinas were scanned using this optimal configuration, then fixed using either glutaraldehyde or formalin. OCT images were taken of the tissue at various stages during the fixation process. Additionally, we examined fixed retinal tissue containing retinal laser lesions as a part of our study of ultrashort-pulsed laser effects on the macacca mulatta retina. Histologic sections were prepared and evaluated. Results: In this presentation, we describe our optical setup and image optimization process and assess the effects of glutaraldehyde and formalin processing on OCT image quality. The OCT images of glutaraldehyde-fixed laser lesions are compared with similar images of laser lesions in-vivo. Fixation artifacts appeared on OCT at 2 to 24 hours. Opacification of the lumen of large vessels was seen at two hours with both glutaraldehyde and formalin, while fixation induced retinal detachment appeared at 24 hours. Overall, there was a grater delineation of the laser lesions by OCT at 24 hours when compared to at 1 or 2 hours of fixation. Conclusions: Fixations induced changes in OCT scans of retinal tissue are present as early as 2 hours after immersion in fixative. Although both glutaraldehyde and formalin fixation preserve much of the tissue structure, these method of fixation have s significant effect on OCT imaging of both normal retinal tissue and laser lesions.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Michelle McCall, Curtis J. Harkrider, Vincent Deramo, Sarah F. Bailey, Katrina P. Winter, Benjamin A. Rockwell, David J. Stolarski, and Cynthia A. Toth "Using optical coherence tomography to elucidate the impact of fixation on retinal laser pathology", Proc. SPIE 4257, Laser-Tissue Interaction XII: Photochemical, Photothermal, and Photomechanical, (9 July 2001); doi: 10.1117/12.434698; https://doi.org/10.1117/12.434698

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