22 May 1995 System to measure fixation shifts with a scanning laser ophthalmoscope
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Abstract
A scanning laser ophthalmoscope (SLO) uses a novel principal to view the retina while simultaneously projecting high resolution targets onto the retina. Consequently, the SLO is potentially an excellent instrument to measure fixation stability in humans. We used a commercially available Rodenstock SLO to project a small cross onto the retina of normal subjects with the HeNe laser and simultaneously view their retinal vasculature with the SLO's infrared diode laser. The video images from the SLO were continuously recorded (at 30 frames per second) with a video-cassette recorder. The video was digitized in 16 consecutive frame increments with a 4 Mbyte frame grabber in a microcomputer. By marking the audio track of the video tape and measuring from the audio mark before digitizing, long segments (1,000's of consecutive frames) can be digitized. We developed software to automatically map the locations of venous crossings at multiple retinal locations. In early work with the system, we verified that the digitization process worked correctly by time-stamping the video and confirming that all video frames were captured without duplication or drop out. We measured the location of 2 retinal points in 1024 consecutive frames of 4 normal subjects and showed that these points could be accurately followed with the automatic system.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Donald A. Frambach, John McDermott, Michael Brosman, Alan Thach, James L. Lambert, "System to measure fixation shifts with a scanning laser ophthalmoscope", Proc. SPIE 2393, Ophthalmic Technologies V, (22 May 1995); doi: 10.1117/12.209847; https://doi.org/10.1117/12.209847
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