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Lakshmisahithi Rani, Christy K Sheehy, Ethan Bensinger, Michael Devereux, Scott B Stevenson, Ari Green; Characterizing microsaccade behavior in a healthy control population using a tracking scanning laser ophthalmoscope (TSLO). Invest. Ophthalmol. Vis. Sci. 2018;59(9):4411. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To analyze the pattern of microsaccades using the tracking scanning laser ophthalmoscope (TSLO) in a healthy control population
Two cohorts of 50 healthy controls with no history of neurological or retinal disease were selected for fixational eye motion recordings using the TSLO system. Subjects first completed the Multidimensional Assessment of Fatigue, a self-reported tool using severity, distress, frequency, and impact converted to a Global Fatigue Index (GFI) score. Next, fixation was recorded with the TSLO system using 840 nm light to raster scan the retina. Subjects were instructed to fixate on the upper right hand corner of the 5x5-degree raster scan for three, 10-sec scans per eye. Offline analysis was performed on extracted eye traces at an eye-tracking frequency of 480 Hz. Number of microsaccades, average microsaccade amplitude and velocity were compared to both fatigue and age.
Data collected contained a wide distribution of age for Cohort 1 (range:23-88,avg:49) and Cohort 2 (range:19-87,avg:50). Fatigue was measured in Cohort 2 (range:1-34.2,avg:11.4). The TSLO successfully detected microsaccade amplitude down to 2.5 arcminutes. Cohort 1 & 2 demonstrated a positive relationship between age and average number of microsaccades (p<0.001 and p=0.01, respectively) with a combined cohort p value of p<0.0011. GFI showed no association with average number of microsaccades (p=0.492), suggesting the positive association between age and number of microsaccades may be independent of fatigue.
A normative database, specific for this task, has been developed for neurological disease research comparisons including Parkinson’s, MS, concussion, and dementia. The data also suggests that TSLO measures microsaccade amplitude and velocity with as much accuracy as the more invasive search coil methods. Indexing fatigue in a large, healthy population demonstrates that fatigue does not substantially impact microsaccade behavior in a 10-sec recording. This cross-sectional data suggests that age is associated with increases in microsaccades and that age may drive changes in fixational eye movements that are important to consider when comparing to disease populations. In the future, normal fixational patterns including square wave jerks,nystagmus,and their directionality will need to be described for a healthy population for direct disease comparison.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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