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Proceedings Paper

Tracking scanning laser ophthalmoscope (TSLO)
Author(s): Daniel X. Hammer; R. Daniel Ferguson; John C. Magill; Michael A. White; Ann E. Elsner; Robert H. Webb
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Paper Abstract

The effectiveness of image stabilization with a retinal tracker in a multi-function, compact scanning laser ophthalmoscope (TSLO) was demonstrated in initial human subject tests. The retinal tracking system uses a confocal reflectometer with a closed loop optical servo system to lock onto features in the fundus. The system is modular to allow configuration for many research and clinical applications, including hyperspectral imaging, multifocal electroretinography (MFERG), perimetry, quantification of macular and photo-pigmentation, imaging of neovascularization and other subretinal structures (drusen, hyper-, and hypo-pigmentation), and endogenous fluorescence imaging. Optical hardware features include dual wavelength imaging and detection, integrated monochromator, higher-order motion control, and a stimulus source. The system software consists of a real-time feedback control algorithm and a user interface. Software enhancements include automatic bias correction, asymmetric feature tracking, image averaging, automatic track re-lock, and acquisition and logging of uncompressed images and video files. Normal adult subjects were tested without mydriasis to optimize the tracking instrumentation and to characterize imaging performance. The retinal tracking system achieves a bandwidth of greater than 1 kHz, which permits tracking at rates that greatly exceed the maximum rate of motion of the human eye. The TSLO stabilized images in all test subjects during ordinary saccades up to 500 °/sec with an inter-frame accuracy better than 0.05 °. Feature lock was maintained for minutes despite subject eye blinking. Successful frame averaging allowed image acquisition with decreased noise in low-light applications. The retinal tracking system significantly enhances the imaging capabilities of the scanning laser ophthalmoscope.

Paper Details

Date Published: 14 July 2003
PDF: 10 pages
Proc. SPIE 4951, Ophthalmic Technologies XIII, (14 July 2003); doi: 10.1117/12.477974
Show Author Affiliations
Daniel X. Hammer, Physical Sciences Inc. (United States)
R. Daniel Ferguson, Physical Sciences Inc. (United States)
John C. Magill, Physical Sciences Inc. (United States)
Michael A. White, Physical Sciences Inc. (United States)
Ann E. Elsner, Schepens Eye Research Institute, Harvard Medical School (United States)
Robert H. Webb, Schepens Eye Research Institute, Harvard Medical School (United States)

Published in SPIE Proceedings Vol. 4951:
Ophthalmic Technologies XIII
Fabrice Manns; Per G. Söderberg; Arthur Ho, Editor(s)

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