Laser applications and system considerations in ocular imaging

Abstract

We review laser applications for primarily in vivo ocular imaging techniques, describing their constraints based on biological tissue properties, safety, and the performance of the imaging system. We discuss the need for cost effective sources with practical wavelength tuning capabilities for spectral studies. Techniques to probe the pathological changes of layers beneath the highly scattering retina and diagnose the onset of various eye diseases are described. The recent development of several optical coherence tomography based systems for functional ocular imaging is reviewed, as well as linear and nonlinear ocular imaging techniques performed with ultrafast lasers, emphasizing recent source developments and methods to enhance imaging contrast. KeywordsRetinal imaging; confocal imaging; Vertical Cavity Surface Emitting Laser (VCSEL); Adaptive Optics; OCT (Optical Coherence Tomography); swept source lasers; ultrafast lasers; nonlinear interactions INTRODUCTONImaging of the eye presents several optical challenges, of which only some are found in microscopy. Millions of neural cells, together with their metabolic support structures, line the inside of the eyeball, forming the retina [1]. Figure 1 shows the large scale view of the eye in cross section, and Figure 2 shows detail of the layers of the retina.The healthy eye must be relatively transparent over a distance of roughly 22 mm, from cornea to retina, to permit the transmission of light to the photoreceptors, which are the neurons that Ann E. Elsner has been a Professor at the Indiana University School of Optometry since 2005 and serves as Director of the Borish Center for Ophthalmic Research. From 1987 until 2005, she was at the Schepens Eye Research Institute, an affiliate of Harvard Medical School, where she served as the group head in Vision and Visual Optics. She is known for the novel application of lasers as sources in imaging and display devices. The applications of the imaging devices are focused on discovering the pathophysiology of diseases of the retina, as well as probing visual function throughout the lifespan. By determining the optical signature of pathological states that are important in patient management, she then develops optical techniques that maximize the chance to detect damage due to disease, with a view towards wide applicability and low cost. She is best known for her retinal imaging work with near infrared sources, polarized light, and image processing techniques that use multiply scattered light to provide improved detection of pathology. Dr. Elsner is a Fellow of the Optical Society of America, and a Fellow of the American Academy of Optometry. She serves as an Associate Editor for Investigative Ophthalmology and Vision Science. She is an author or co-author on more than 75 papers in refereed journals, and over 150 published abstracts from major scientific meetings. Matthew S. Muller has been an Optical Engineer at the Indiana University School of Optometry since January, 2008. He received his Master's of Science (Engin...

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